Rabies

Topic Overview

Summary

Rabies is an acute, progressive, and almost invariably fatal viral encephalomyelitis caused by Lyssavirus species (family Rhabdoviridae), most commonly classical rabies virus (RABV). The virus is transmitted primarily through the saliva of infected mammals via bites, scratches, or mucous membrane contact. [1,2] Rabies has the highest case-fatality ratio of any infectious disease—virtually 100% once clinical symptoms develop—but is almost entirely preventable with timely post-exposure prophylaxis (PEP). [3] The disease is characterised by progressive neurological dysfunction, with pathognomonic features including hydrophobia (fear of water) and aerophobia (fear of air/drafts), reflecting severe brainstem dysfunction. [4] Despite being vaccine-preventable, rabies causes an estimated 59,000 deaths annually worldwide, predominantly in Asia and Africa where canine rabies remains endemic. [5]

Key Facts

• Causative Agent: Lyssavirus genus (14 species); rabies virus (genotype 1) causes > 95% of human cases
• Transmission: Primarily via bite from rabid animal; saliva contact with broken skin or mucous membranes; rarely aerosol (bat caves) or transplantation
• Reservoir Species: Dogs (> 99% of human cases globally), bats (main wild reservoir in Americas/Europe), foxes, raccoons, skunks, jackals, mongooses
• Incubation Period: 20-90 days (median 1-3 months); range 4 days to > 6 years; inversely related to distance from CNS
• Case-Fatality Rate: 100% once symptomatic (only ~30 survivors ever documented, most with severe neurological sequelae)
• Global Burden: 59,000 deaths/year; 40% in children less than 15 years; 95% of deaths in Asia and Africa
• Prevention: Post-exposure prophylaxis (wound washing + vaccine + immunoglobulin) is nearly 100% effective if given before symptom onset
• Pathognomonic Signs: Hydrophobia (spasms triggered by swallowing), aerophobia (spasms from air currents)
• UK Status: Terrestrial rabies-free since 1902; European bat lyssaviruses (EBLV-1, EBLV-2) present in UK bats

Clinical Pearls

The "No Time Limit" Principle: There is no upper time limit for initiating PEP after potential rabies exposure—even if months have elapsed, PEP should be given if the patient has not developed symptoms. The virus may remain localised at the bite site for weeks to months before neuroinvasion.

Bat Exposure = High Risk: Any bat contact where a bite or scratch cannot be confidently excluded requires PEP. Bat teeth can leave imperceptible wounds; cases include sleeping persons who wake to find a bat in the room.

Hydrophobia is Pathognomonic: The sight, sound, or thought of water triggers violent pharyngeal and laryngeal spasms with intense anxiety—this feature is virtually diagnostic of rabies and occurs in ~50-80% of patients with furious rabies.

RIG is Time-Critical: Rabies immunoglobulin (RIG) must be given within 7 days of starting vaccine; beyond day 7, endogenous antibody response has begun and RIG may interfere. Maximum anatomically feasible RIG should be infiltrated directly into/around wounds.

Dog Observation Period: In endemic areas, if a dog/cat can be observed for 10 days and remains healthy, rabies is excluded. However, PEP should still be initiated immediately pending observation results.

Why This Matters Clinically

Rabies represents a unique clinical emergency: a disease that is 100% preventable with appropriate intervention yet 100% fatal once clinical manifestations appear. The median time from symptom onset to death is 7 days (range 2-21 days). [6] Clinicians must have a low threshold for suspecting rabies in patients with:

• Unexplained acute encephalitis, especially with agitation or phobic spasms
• Recent travel to endemic areas (particularly South/Southeast Asia, Africa, South America)
• Any animal bite or bat exposure in the past year

Early recognition of exposure risk and immediate initiation of PEP has saved countless lives. Conversely, delays in PEP due to failure to recognise exposure risk or unavailability of biologics in remote areas account for most preventable deaths. In the UK, the National Travel Health Network and Centre (NaTHNaC) and Public Health England (PHE) provide 24/7 advice on rabies risk assessment and PEP access. Every Emergency Department should have clear protocols for accessing PEP urgently.

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Visual Summary

Visual assets to be added:

• World rabies endemic country map
• Post-exposure prophylaxis algorithm
• Wound care steps infographic
• Negri body histopathology image

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Epidemiology

Global Burden

Rabies remains a significant public health problem in developing countries, with a disproportionate impact on children and rural communities with limited access to post-exposure prophylaxis. [5,7]

Annual Mortality:

• Estimated deaths: 59,000 per year globally (95% CI: 25,000-159,000)
• Asia: 59.6% of global deaths (~35,000 deaths)
• Africa: 36.4% of global deaths (~21,500 deaths)
• Latin America: less than 1% of global deaths (less than 500 deaths, due to successful dog vaccination programmes)
• Paediatric deaths: 40% of deaths occur in children less than 15 years old

Economic Burden:

• Direct medical costs: ~$8.6 billion USD annually
• PEP delivery costs: ~$1.7 billion annually (majority in Asia)
• Lost productivity from premature death: ~$6.9 billion annually

Transmission Dynamics

Canine Rabies (99% of human cases):

• Dogs are the source of 99% of human rabies deaths worldwide
• Primarily affects low-income countries in Asia and Africa
• Highest incidence in rural areas with large unvaccinated dog populations
• Dog-to-dog transmission perpetuates endemic cycles

Wildlife Rabies:

• Americas: Bats, raccoons, skunks, foxes (sylvatic rabies)
• Europe: Foxes (largely controlled by oral vaccination), bats (EBLV)
• Africa: Jackals, mongooses (in addition to dogs)
• Asia: Wolves (Central Asia), foxes (China)

Geographic Distribution

Canine Rabies Endemic Regions:

• Indian Subcontinent: India (~20,000 deaths/year), Bangladesh, Pakistan, Nepal, Afghanistan
• Southeast Asia: Myanmar, Cambodia, Laos, Philippines, Vietnam, Indonesia
• Sub-Saharan Africa: Most countries, particularly East/West Africa
• Latin America: Some areas of Amazon basin, Haiti, Guatemala

Rabies-Free Countries/Territories:

• Europe: UK, Ireland, Norway, Sweden, Finland, Iceland, Channel Islands
• Asia-Pacific: Japan, Singapore, Taiwan, Australia, New Zealand, Pacific islands
• Caribbean: Most islands (Barbados, Jamaica, Bermuda, etc.)

Sylvatic (Wildlife) Rabies Only:

• USA, Canada (canine rabies eliminated; bat/wildlife rabies persists)
• Western Europe (fox rabies largely eliminated; bat lyssaviruses remain)

United Kingdom Epidemiology

Historical Context:

• Last indigenous human rabies case: 1902 (dog bite)
• Last indigenous terrestrial animal case: 1922 (dog)
• Maintained rabies-free status through strict quarantine regulations

Imported Human Cases (1946-present):

• 28 imported human rabies cases in UK since 1946
• Most recent: 2018 (Moroccan dog bite, presented with encephalitis in UK)
• 2012: UK bat-variant EBLV-2 (bat handler who refused PEP)
• Median delay from exposure to symptom onset: 35 days (range: 13 days to 6+ months)

European Bat Lyssaviruses (EBLV) in UK Bats:

• EBLV-1 and EBLV-2 detected in UK bat populations (predominantly Daubenton's bats and serotine bats)
• Passive surveillance: 5-10% of submitted bat brains test positive
• Active surveillance: less than 1% prevalence in healthy bat populations
• One human death (Scotland, 2002): Bat conservationist bitten; developed rabies 5 weeks later
• Bat workers, handlers, and any person bitten/scratched by UK bat require PEP

Risk Groups Requiring Pre-Exposure Vaccination

Travel-Associated Rabies Exposures

UK Travel Data:

• ~1,000-2,000 UK travellers receive PEP abroad annually
• ~500-1,000 receive PEP in UK after returning from travel
• Most exposures: India, Thailand, Nepal, Sri Lanka, Kenya, Morocco

High-Risk Travel Activities:

• Volunteering at animal shelters/sanctuaries
• Trekking/camping in remote areas
• Cycling tours (increased animal encounters)
• Visiting friends/relatives in endemic rural areas (longer stays, less caution)
• Medical/veterinary electives in endemic countries

Rabies Elimination Efforts

WHO Goal: Zero Human Rabies Deaths by 2030

• Focus on mass dog vaccination (70% coverage required to break transmission)
• Improved access to PEP in rural endemic areas
• Integrated bite case management (IBCM)

Success Stories:

• Latin America: Canine rabies reduced by 95% since 1980s through dog vaccination
• Philippines: Bohol province eliminated canine rabies (2013) through mass dog vaccination
• KwaZulu-Natal, South Africa: Reduced human cases by 90% with dog vaccination + free PEP

Challenges:

• Free-roaming dog populations in resource-limited settings
• Limited cold-chain infrastructure for vaccine storage
• Inadequate supply of rabies immunoglobulin (globally only ~50% of need met)
• Lack of awareness in rural communities

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Pathophysiology

Virology and Molecular Biology

Lyssavirus Genus (Family Rhabdoviridae): The genus Lyssavirus comprises 14 phylogenetically distinct species, all capable of causing fatal encephalitis. [1,8] Classical rabies virus (RABV, genotype 1) is responsible for > 95% of human rabies cases globally. Other lyssaviruses include:

• Phylogroup I (Classic rabies-like): RABV, Australian bat lyssavirus (ABLV), Duvenhage virus, European bat lyssaviruses (EBLV-1, EBLV-2)
• Phylogroup II: Lagos bat virus, Mokola virus, Shimoni bat virus
• Phylogroup III: West Caucasian bat virus (WCBV), Ikoma lyssavirus (IKOV)

Virion Structure:

• Morphology: Bullet-shaped or bacilliform virion (~180 nm × 75 nm)
• Genome: Non-segmented, negative-sense, single-stranded RNA (~12 kb)
• Structural proteins:
  • "G protein (glycoprotein): Surface spikes; mediates receptor binding and membrane fusion; primary target of neutralising antibodies"
  • "M protein (matrix): Links envelope to nucleocapsid; role in viral budding"
  • "N protein (nucleoprotein): Encapsidates genomic RNA; forms ribonucleoprotein (RNP) core"
  • "L protein (polymerase): RNA-dependent RNA polymerase; viral replication"
  • "P protein (phosphoprotein): Cofactor for L polymerase; prevents innate immune activation"

Genetic Stability and Variation:

• RABV is relatively genetically stable (mutation rate ~10⁻⁵ substitutions/site/year)
• Distinct phylogenetic clades correlate with geographic distribution and reservoir species
• Canine RABV variants differ from bat/wildlife variants
• Vaccine strains (e.g., Pasteur virus, SAD B19) are attenuated through cell culture adaptation

Transmission Mechanisms

Primary Route: Bite from Infected Animal

• Virus is present in saliva of infected animals 1-5 days before symptom onset
• Virus concentration in saliva: 10³-10⁶ infectious units/mL
• Transmission risk per bite: ~15-50% (varies with wound depth, location, viral load)
• Deep penetrating wounds > superficial abrasions > licks on intact skin (no transmission)

Secondary Routes:

• Scratches/Claws: If contaminated with saliva (e.g., animal licking claws before scratching)
• Mucous Membrane Exposure: Virus can cross mucosa (conjunctiva, oral cavity, respiratory tract)
• Aerosol: Extremely rare; documented in bat caves with high aerosolised bat saliva, laboratory accidents
• Organ Transplantation: ~35 documented cases; donors died of "undiagnosed encephalitis" and organs transmitted rabies to recipients
• Transplacental: Theoretically possible but exceedingly rare
• No person-to-person transmission: Except via transplantation; saliva of infected humans has low viral load

Molecular Pathogenesis: From Bite to Brain

Phase 1: Inoculation and Local Replication (Days to Weeks)

1. Virus deposited in tissue via bite/scratch
2. Initial replication in muscle cells (myocytes) at wound site
3. Virus remains localised in muscle for variable period (days to months)—this is the "eclipse phase" during which PEP is maximally effective

Phase 2: Neuroinvasion (Peripheral Nerve Entry) Rabies virus exhibits strict neurotropism, explained by several molecular mechanisms: [9]

• Nicotinic acetylcholine receptor (nAChR) binding: G protein binds neuronal nAChR at neuromuscular junctions and muscle spindles
• Neural cell adhesion molecule (NCAM): G protein interacts with NCAM on neurons
• p75 neurotrophin receptor: Alternative entry point on sensory neurons
• Virus enters peripheral nerve terminals (motor neurons, sensory neurons) at wound site

Phase 3: Centripetal Axonal Transport (Weeks to Months)

• Virus travels via retrograde axonal transport within peripheral nerves toward CNS
• Transported within endosomes along microtubules (dynein motor protein complex)
• Speed: ~12-24 mm/day (slow, explaining prolonged incubation)
• Spreads trans-synaptically across neuronal connections
• No viremia: Virus remains cell-associated and neurotropic; does not enter bloodstream

Phase 4: CNS Replication and Dissemination (Days)

• Virus reaches spinal cord → brainstem → limbic system → cortex
• Preferential tropism for brainstem nuclei (medulla, pons) and limbic structures (hippocampus, amygdala)
• Extensive replication in neurons; minimal neuronal death (apoptosis induced but limited necrosis)
• Neuronal dysfunction > neuronal destruction explains clinical features
• Inflammatory infiltrate is modest (perivascular lymphocytic cuffing) relative to severity of disease

Phase 5: Centrifugal Spread (Symptomatic Phase)

• Virus travels from CNS back to peripheral tissues via anterograde axonal transport
• High concentrations in:
  • "Salivary glands: Explains transmission via saliva"
  • "Skin (especially nape of neck): Hair follicle innervation; used for diagnosis (skin biopsy)"
  • "Cornea: Allows antemortem diagnosis via corneal impressions"
  • Cardiac muscle, adrenal glands, pancreas (less clinically relevant)

Neuropathological Features

Macroscopic Findings:

• Brain appears grossly normal or shows non-specific changes
• Mild meningeal congestion
• Cerebral oedema (late, variable)

Microscopic Findings:

• Negri bodies (pathognomonic when present):
  • Eosinophilic, cytoplasmic, ovoid inclusions (2-10 μm diameter)
  • Contain viral ribonucleoprotein (RNP) aggregates
  • Most abundant in pyramidal neurons of hippocampus (Ammon's horn), cortical neurons, Purkinje cells of cerebellum
  • Present in ~50-80% of rabies cases (absence does not exclude rabies)
  • More common in furious rabies than paralytic rabies
• Perivascular lymphocytic cuffing: Mononuclear infiltrates around small vessels
• Microglial nodules (Babes' nodules): Focal microglial proliferation
• Neuronophagia: Phagocytosis of damaged neurons
• Minimal neuronal necrosis: Death from dysfunction, not destruction

Immunohistochemistry:

• Rabies virus antigen detected using fluorescent antibody technique (FAT)—gold standard for diagnosis
• More sensitive than Negri body detection
• Abundant antigen in brainstem, hippocampus, cerebellum

Incubation Period Determinants

The incubation period (time from exposure to symptom onset) is highly variable but typically 20-90 days. [2] Factors influencing incubation:

Shorter Incubation (less than 30 days):

• Bites to head/neck/upper limbs (shorter distance to CNS)
• Deep, multiple, or extensive wounds (higher viral inoculum)
• High viral load in inoculum
• Immunocompromised host (diabetes, HIV, corticosteroids)
• Children (shorter neural pathway distances)

Longer Incubation (> 90 days):

• Bites to lower limbs (longer distance to CNS)
• Superficial scratches or minor wounds
• Low viral load
• Single wound
• Rare cases: > 1 year incubation documented; longest recorded ~6-7 years

Why Rabies is Universally Fatal

Several mechanisms explain the near-100% lethality once clinical rabies develops: [10]

1. CNS Immune Privilege: Limited immune surveillance in CNS allows unchecked viral replication
2. Neuronal Dysfunction Without Destruction: Virus impairs neurotransmission without triggering sufficient immune response to clear infection
3. Blood-Brain Barrier Integrity: Virus rarely elicits enough inflammation to disrupt BBB and allow systemic immune effectors into CNS
4. Delayed Antibody Response: Neutralising antibodies appear too late (after symptom onset) and cannot cross BBB effectively
5. Brainstem Involvement: Infection of vital cardiorespiratory centres causes autonomic dysregulation and respiratory failure
6. Lack of Innate Immune Activation: P protein suppresses type I interferon response, allowing viral evasion of early immune defences

Immune Evasion Strategies

Rabies virus has evolved multiple mechanisms to evade host immunity: [8]

• P protein antagonises innate immunity: Inhibits RIG-I and TLR signalling → reduced interferon production
• Sequestration in neurons: Neurons are poor antigen-presenting cells; limited MHC class I expression
• Limited cytopathic effect: Minimal neuronal lysis prevents release of danger signals
• Trans-synaptic spread: Cell-to-cell transmission avoids extracellular exposure to antibodies
• Glycoprotein shielding: G protein conformational changes evade neutralising antibodies

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Clinical Presentation

Rabies presents in two main clinical forms—furious (encephalitic) and paralytic (dumb)—preceded by a prodromal phase. Recognition of pathognomonic features (hydrophobia, aerophobia) is key to diagnosis. [4,11]

Prodromal Phase (2-10 days)

The prodrome is non-specific and easily missed, but one feature is highly suggestive of rabies:

Non-Specific Symptoms:

• Low-grade fever (38-38.5°C)
• Malaise, fatigue, anorexia
• Headache (often generalised)
• Nausea, vomiting, abdominal discomfort
• Myalgia
• Anxiety, irritability, restlessness
• Insomnia, depression

Highly Suggestive Feature:

• Pain, paraesthesia, or pruritus at healed bite site (30-80% of cases) [4]
  • May radiate along affected limb
  • Occurs weeks to months after wound has healed
  • Reflects viral replication in local sensory nerves
  • Should prompt immediate rabies evaluation in appropriate exposure context

Acute Neurological Phase (2-10 days)

Furious (Encephalitic) Rabies (70-80% of cases)

This is the "classic" presentation and includes pathognomonic features: [11]

Detailed Description of Hydrophobia:

• Patient experiences intense thirst but cannot drink
• Attempting to swallow water (or even seeing/hearing water) triggers:
  • Violent contraction of diaphragm, accessory respiratory muscles
  • Laryngospasm with stridor
  • Jerking of neck and trunk
  • Extreme anxiety, terror, sense of impending death
  • Gasping, choking
• Spasm lasts seconds to minutes, followed by exhaustion
• Between episodes, patient is aware and distressed
• Mechanism: Viral infection of medullary centres controlling swallowing and respiration

Detailed Description of Aerophobia:

• Similar spasms triggered by air movement across skin (especially face)
• Can be elicited diagnostically by gently fanning patient or blowing on face
• Highly specific for rabies (uncommon in other encephalitides)

Paralytic (Dumb) Rabies (20-30% of cases)

Less recognised form of rabies, often misdiagnosed as Guillain-Barré syndrome (GBS): [12]

Clinical Features:

• Ascending flaccid paralysis starting from bitten limb
• Progressive over days
• Sphincter involvement (urinary retention, constipation)
• Sensory symptoms less prominent (unlike GBS, where paraesthesia common)
• Relative preservation of consciousness initially
• Less agitation and fewer phobic spasms compared to furious rabies
• Hydrophobia and aerophobia may be absent or subtle
• Fever typically present
• Facial nerve palsy, ophthalmoplegia may occur

Distinguishing from GBS:

Why Paralytic Rabies is Often Missed:

• Lack of "classic" hydrophobia/agitation leads to delayed consideration of rabies
• May present to neurology rather than infectious diseases
• History of animal bite may be remote (weeks/months) and not volunteered
• Misdiagnosis as GBS, poliomyelitis, transverse myelitis, or other myelopathies delays specific questioning about exposures

Coma and Terminal Phase (0-14 days)

Progression to Coma:

• Occurs within 7-14 days of symptom onset (median 7 days) [6]
• Preceded by increasing obtundation, seizures (generalised or focal)
• Respiratory muscle paralysis necessitates intubation
• Coma is typically deep (GCS 3-6)

Terminal Events:

• Respiratory failure (most common cause of death)
  • Central apnoea (brainstem dysfunction)
  • Neuromuscular respiratory paralysis
  • Aspiration pneumonia
• Cardiovascular collapse
  • Severe autonomic dysfunction
  • Arrhythmias (ventricular tachycardia, asystole)
  • Myocarditis (direct viral involvement or catecholamine storm)
• Cerebral herniation (if cerebral oedema develops)
• Multi-organ failure (late)

Time to Death:

• Median survival from symptom onset: 7 days (range 2-21 days)
• Survival > 14 days with intensive support is rare
• Prolonged survival (weeks) reported with intensive care but almost always with ultimate fatal outcome or severe neurological sequelae

Atypical and Rare Presentations

Mixed Furious-Paralytic Form:

• Some patients exhibit features of both forms
• May start with paralytic features and progress to agitation, or vice versa

Brainstem Syndrome:

• Cranial nerve palsies (III, VI, VII, IX, X, XII)
• Nystagmus, ophthalmoplegia
• Bulbar palsy (dysarthria, dysphagia)
• May mimic brainstem stroke or encephalitis

Cerebellar Syndrome:

• Ataxia, dysmetria, intention tremor
• Nystagmus
• Rare primary presentation

Spinal Cord Syndrome:

• Isolated myelitis
• May mimic poliomyelitis, transverse myelitis
• Especially with bat rabies variants

Post-Transplant Rabies:

• Incubation often very short (13-27 days)
• Donor usually had "unexplained encephalitis"
• Multiple recipients affected if multiple organs transplanted
• Fulminant course

Paediatric Considerations

Children account for 40% of rabies deaths globally: [5]

Age-Specific Features:

• Higher risk of exposure: Play with animals, less cautious, cannot report minor bites
• Shorter incubation: Proportionally shorter distances to CNS
• Non-specific prodrome often dominates: Fever, irritability, change in behaviour
• Delayed recognition: Rabies less suspected in children; often diagnosed as viral encephalitis
• Rapid progression: Median time from symptom onset to death may be shorter (4-7 days)

Red Flags in Children:

• Unexplained agitation, biting, fear of water in endemic areas
• Acute encephalitis with animal exposure history (any timeframe)
• Paralysis following animal bite (even weeks/months later)

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Clinical Examination

Exposure History (Most Critical Component)

A detailed exposure history is the cornerstone of rabies risk assessment and is often more important than examination findings in asymptomatic patients presenting after potential exposure.

Structured Exposure Assessment ("5 Ws + H"):

1. WHAT animal was involved?

• High-risk: Dog, cat (in endemic areas), bat (anywhere), fox, raccoon, skunk, jackal, mongoose, wolf
• Low-risk: Livestock (cattle, horses), rodents (rats, mice, squirrels—very rare transmission), rabbits, birds
• No risk: Insects, reptiles, fish
• Unknown animal: Treat as high-risk if in endemic area

2. WHERE did the exposure occur?

• Country/region: Endemic vs rabies-free
• Urban vs rural: Rural areas typically higher risk
• Provoked vs unprovoked: Unprovoked attacks more concerning (suggest animal is rabid)

3. WHEN did the exposure occur?

• Exact date/time (to determine incubation period)
• Delay in seeking care (does not negate need for PEP if asymptomatic)

4. WHO was exposed (patient factors)?

• Age (children at higher risk)
• Immunocompromised status
• Pre-exposure vaccination status

5. WHY did the bite occur?

• Provoked (patient interacted with animal) vs unprovoked (animal attacked without cause)
• Unprovoked attacks suggest rabies in animal

HOW: Type and Severity of Exposure

WHO Exposure Category Classification:

Specific Scenarios:

• Bat exposure: Any contact where bite/scratch cannot be confidently excluded = Category III
  • "This includes: bat found in room of sleeping person, young child, intoxicated person, or cognitively impaired person"
  • Bat teeth/claws are tiny; wounds may be imperceptible
• Saliva contact: Lick on open wound, mucous membrane (eyes, mouth, nose) = Category III
• Handling of carcass: If saliva contact with broken skin = Category III
• Indirect contact: Touching object contaminated with saliva = generally no risk (virus does not survive long outside body)

Examination in Asymptomatic Patient (Post-Exposure)

General Inspection:

• Overall health status
• Signs of anxiety (common after potential rabies exposure)

Wound Assessment:

• Location: Face/neck/hands vs limbs/trunk (affects incubation period)
• Type: Bite (depth, number of teeth marks), scratch, abrasion, laceration
• Severity: Superficial vs deep, single vs multiple
• Signs of infection: Erythema, purulence, cellulitis, lymphangitis (unrelated to rabies but requires management)
• Healing status: Fresh vs healing vs healed
• Photograph wounds for documentation

Neurological Examination (Should be Normal if Asymptomatic):

• Mental status (orientation, mood, affect)
• Cranial nerves (II-XII)
• Motor (tone, power, coordination)
• Sensory (light touch, pinprick—assess for hyperaesthesia at bite site)
• Reflexes (muscle stretch, plantar)
• Gait

Decision Point:

• If asymptomatic and exposure is Category II or III → initiate PEP immediately
• Do not wait for symptoms to develop (once symptoms appear, rabies is untreatable)

Examination in Suspected Clinical Rabies

When a patient presents with acute encephalitis and rabies is in the differential (travel to endemic area, animal exposure, unexplained encephalitis with agitation):

Hydrophobia Assessment (Diagnostic Test):

• Offer patient a glass of water and ask them to drink
• Positive test: Patient exhibits visible distress at sight of water; attempts to drink trigger violent pharyngeal/laryngeal spasms, jerking of head/neck, gasping, and extreme anxiety
• Between attempts, patient is lucid and aware but terrified of drinking
• Note: Hydrophobia is specific to rabies; other encephalitides do not cause this

Aerophobia Assessment:

• Fan air gently toward patient's face or blow softly
• Positive test: Triggers similar spasms to hydrophobia
• Highly specific for rabies

Mental Status:

• Orientation: Often preserved initially, especially in lucid intervals
• Behaviour: Agitation, hyperactivity, aggression, confusion, hallucinations (visual or auditory), delirium
• Affect: Extreme anxiety, terror, irritability
• Fluctuating consciousness: Periods of lucidity alternating with confusion/agitation

Cranial Nerve Examination:

• II (Optic): Pupils may be dilated (mydriasis) due to autonomic dysfunction
• III, IV, VI (Ocular movements): May be impaired in paralytic rabies or late furious rabies
• V (Trigeminal): Sensory usually intact
• VII (Facial): May show weakness in paralytic rabies
• IX, X (Glossopharyngeal, Vagus): Pharyngeal/laryngeal spasms, dysphagia, dysphonia
• XI (Spinal accessory): Usually intact
• XII (Hypoglossal): May show fasciculations or deviation in paralytic rabies

Motor Examination (Furious Rabies):

• Tone: May be increased (spasticity) or fluctuating
• Power: Generally preserved initially; may weaken in terminal phase
• Coordination: Impaired due to agitation and involuntary movements
• Involuntary movements: Myoclonic jerks, tremor, chorea (rare)

Motor Examination (Paralytic Rabies):

• Tone: Flaccid (hypotonic)
• Power: Progressive ascending weakness starting in bitten limb
• Reflexes: Variable (may be preserved early, unlike GBS where reflexes lost early)
• Fasciculations: May be present

Sensory Examination:

• Paraesthesia/pain at bite site: May report tingling, burning, itching along bitten limb (dermatomal distribution)
• Distal sensory loss: Uncommon (unlike GBS)

Autonomic Examination:

• Vital signs: Tachycardia (HR > 100), hypertension (SBP > 140), fever (> 38°C), tachypnoea (RR > 20)
• Hypersalivation: Drooling, inability to handle oral secretions
• Lacrimation: Excessive tearing
• Diaphoresis: Profuse sweating
• Mydriasis: Dilated pupils, sluggish light reflex
• Priapism: Check in males (15-30% of cases)

Respiratory Examination:

• Hyperventilation: Rapid, irregular breathing
• Stridor: If laryngospasm present
• Use of accessory muscles: Intercostal, sternocleidomastoid
• Paradoxical breathing: If diaphragmatic involvement

Cardiovascular Examination:

• Arrhythmias: Palpate pulse for irregularity; ECG essential
• Hypertension: Often marked
• Hypotension: Late sign (pre-terminal)

Isolation and Safety Precautions:

• Standard precautions: Gowns, gloves, eye protection when in contact with secretions
• Avoid bites: Patient may bite during agitation (although human saliva has very low viral load, risk is theoretical)
• Minimise stimulation: Dim lights, quiet environment (reduces phobic spasms)

Clinical Scoring and Diagnostic Criteria

No formal diagnostic score exists, but combination of features strongly suggests rabies:

Strong Clinical Suspicion (Proceed to Diagnostic Testing):

1. Hydrophobia OR aerophobia (either alone is highly specific)
2. Acute encephalitis (fever + altered mental status)
3. Exposure history (animal bite in endemic area within 1 year)
4. Absence of alternative diagnosis

Supportive Features:

• Pain/paraesthesia at bite site during prodrome
• Hypersalivation, autonomic dysfunction
• Lucid intervals alternating with agitation
• Rapid progression to coma (less than 2 weeks)

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Investigations

Pre-Symptomatic (Exposure Assessment Context)

Key Principle: No laboratory tests are required or useful for deciding whether to administer PEP. The decision is based entirely on exposure risk assessment.

• Do NOT delay PEP to await test results
• Do NOT test asymptomatic exposed persons (no test can detect rabies during incubation)
• If in doubt about exposure risk, err on side of giving PEP

Animal Testing (If Feasible):

• If biting animal is available (captured, killed, or died)
• Brain tissue examination (direct fluorescent antibody test—DFA) is gold standard
• Animal must be euthanised to obtain brain tissue (cannot test live animal)
• Requires decapitation and rapid transport of head (refrigerated, not frozen)
• Result available within 24-48 hours
• If animal tests negative → PEP can be discontinued
• If animal tests positive → Continue PEP

Animal Observation (Alternative to Euthanasia):

• Healthy dog or cat that bit a person can be observed for 10 days
• If animal remains healthy for 10 days → rabies excluded (virus only in saliva 1-5 days before animal shows symptoms)
• Start PEP immediately; stop if animal remains well at day 10
• Does NOT apply to wildlife (e.g., bats, foxes) — these should be tested, not observed

Symptomatic Disease (Confirmation of Clinical Rabies)

Diagnosis of clinical rabies requires high index of suspicion and specialised testing. Multiple samples on different days increase diagnostic sensitivity. [13]

Antemortem Diagnostic Tests:

Recommended Antemortem Diagnostic Strategy (UK PHE Protocol):

Collect all of the following at presentation and repeat on days 3, 7, 14 if still alive:

1. Saliva (1-3 mL) for RT-PCR
2. Nuchal skin biopsy (3-5 mm punch biopsy from nape of neck, at hairline) for DFA
3. CSF (if lumbar puncture safe) for RT-PCR and antibody detection
4. Serum for antibody detection (useful if unvaccinated)

Interpretation:

• Positive result on any test → rabies confirmed
• Negative results do NOT exclude rabies (especially early in disease)
• Clinical diagnosis may be necessary if tests negative but high suspicion

Post-Mortem Diagnostic Tests (Gold Standard):

Negri Bodies:

• Pathognomonic intracytoplasmic inclusions composed of viral ribonucleoprotein
• Eosinophilic, ovoid, 2-10 μm diameter
• Most abundant in pyramidal neurons of hippocampus (Ammon's horn)
• Also found in cortical neurons, Purkinje cells of cerebellum
• Present in only 50-80% of rabies cases → absence does not exclude rabies
• More common in furious rabies than paralytic rabies
• Named after Adelchi Negri (1903)

Non-Specific Laboratory Findings (Supportive):

Cerebrospinal Fluid (CSF) Analysis:

• Often normal or shows mild abnormalities
• Lymphocytic pleocytosis: 10-100 cells/μL (in ~50% of cases)
• Protein: Normal or mildly elevated (0.4-1.5 g/L)
• Glucose: Normal
• No organisms on Gram stain or culture
• CSF findings cannot distinguish rabies from other viral encephalitides

Haematology:

• White cell count: Normal or mild leucocytosis (10-15 × 10⁹/L)
• Lymphocyte count: May be normal or slightly reduced

Biochemistry:

• Usually normal
• Hyponatraemia: May occur (SIADH from hypothalamic involvement)

Neuroimaging (MRI Brain):

MRI Findings (Non-Specific, Present in ~50% of Cases):

• T2/FLAIR hyperintensity in:
  • Brainstem (medulla, pons, midbrain)
  • Hippocampus, thalamus
  • Deep grey matter (basal ganglia)
  • Spinal cord (in paralytic rabies)
• Contrast enhancement: Usually absent or minimal (unlike bacterial/fungal encephalitis)
• Normal MRI does not exclude rabies (50% of cases have normal imaging)

CT Brain:

• Often normal
• Less sensitive than MRI
• May show non-specific oedema

Electroencephalography (EEG):

• Non-specific abnormalities
• Diffuse slowing (delta/theta activity)
• No periodic discharges (unlike HSV encephalitis, CJD)
• Not diagnostically useful

Electromyography (EMG) and Nerve Conduction Studies (Paralytic Rabies):

• May help differentiate from GBS
• Rabies: Normal or reduced amplitude; normal conduction velocity
• GBS: Reduced conduction velocity; conduction block; prolonged F-wave latency

Differential Diagnosis

In Pre-Symptomatic/Prodromal Patient:

• Viral prodrome (influenza, other viral illnesses)
• Wound infection (cellulitis, abscess)
• Anxiety disorder (following traumatic animal encounter)

In Symptomatic Patient with Encephalitis:

Note on Tetanus vs Rabies:

• Both can present with pharyngeal spasms
• Tetanus: Spasms are tonic, sustained, generalised muscle rigidity; triggered by stimuli but not by water/air specifically; no encephalopathy; patient remains conscious and oriented
• Rabies: Spasms are brief, clonic; specifically triggered by water (hydrophobia) or air (aerophobia); encephalopathy, agitation, fluctuating consciousness

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Classification & Staging

WHO Post-Exposure Prophylaxis Categories

The World Health Organization classifies rabies exposures into three categories to guide PEP decisions: [3,14]

Key Clarifications:

• "Suspect rabid animal": Any mammal in endemic area; wild carnivores (bats, foxes, raccoons, etc.); unvaccinated dogs/cats; animal with abnormal behaviour
• Category III includes ALL bat exposures where bite cannot be excluded (bats have tiny teeth; bite may be imperceptible)
• Category I exposures can be upgraded to Category II or III if:
  • Animal subsequently develops rabies
  • Patient is immunocompromised
  • Exposure was to a bat

UK Risk Assessment Framework (PHE Guidelines)

Public Health England uses a more nuanced risk assessment based on:

1. Country Risk Classification:

2. Animal Risk Classification:

3. Type of Exposure (Same as WHO Categories I/II/III)

4. Pre-Exposure Vaccination Status:

UK PEP Decision Algorithm (Simplified):

EXPOSURE IN UK
├─ Bat contact (bite/scratch cannot be excluded) → Category III → PEP (vaccine + RIG)
├─ Bat contact (no bite/scratch) → No PEP
├─ Terrestrial mammal bite → No PEP (UK is rabies-free)
└─ Imported animal (pet imported less than 6 months ago) → Risk assessment; contact PHE

EXPOSURE ABROAD
├─ Rabies-free country + terrestrial animal → No PEP
├─ Rabies-free country + bat → Category III → PEP (vaccine + RIG)
├─ Endemic country
│   ├─ Category I exposure → No PEP
│   ├─ Category II exposure → Vaccine only
│   └─ Category III exposure → Vaccine + RIG
└─ If uncertain → Give PEP (can always stop; cannot reverse death)

Rabies Clinical Staging (Symptomatic Patients)

Note: Milwaukee Protocol (induced coma + antiviral therapy) has been attempted in ~50 cases worldwide with ~6 survivors (12% survival), but most survivors have severe neurological disability. [15] It is highly controversial and not recommended as standard care.

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Management

Overview Principles

Key Concept: Rabies is virtually 100% fatal once symptomatic but nearly 100% preventable with timely post-exposure prophylaxis (PEP). Management therefore focuses on:

1. Prevention (pre-exposure vaccination for high-risk groups)
2. PEP (wound care + vaccine + immunoglobulin) for exposures
3. Palliative care for clinical rabies (curative treatment is not possible)

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Post-Exposure Prophylaxis (PEP)

PEP consists of three components, all of which must be initiated as soon as possible after exposure: [14,16]

1. Immediate Wound Care (Critical First Step)

Thorough wound washing is the single most important intervention and can reduce rabies risk by up to 90% by mechanically removing virus before neuroinvasion. [3]

Wound Washing Protocol:

1. Irrigate wound immediately with copious running water for ≥15 minutes
2. Use soap or detergent (surfactants disrupt viral envelope)
3. Apply virucidal agent after washing:
   • Povidone-iodine (preferred)
   • Ethanol (70%) or isopropanol
   • Chlorhexidine (alternative)
4. Do NOT scrub vigorously (may drive virus deeper into tissue)
5. Do NOT apply caustic agents (phenol, acids—tissue damage may worsen outcome)

Wound Management:

• Avoid primary closure (suturing) if possible (allows drainage; reduces viral load)
• If closure essential for cosmetic/functional reasons:
  • Ensure RIG has been infiltrated into wound first
  • Use loose sutures or delayed primary closure (48-72 hours)
• Debridement: Remove devitalised tissue
• Tetanus prophylaxis: According to standard guidelines (booster if > 10 years since last dose; immunoglobulin if never vaccinated)
• Antibiotics: If wound infection likely (NOT routinely for rabies prevention)
  • Co-amoxiclav 625 mg TDS for 5-7 days (covers Pasteurella, Staphylococcus, anaerobes)
  • "Penicillin allergy: Doxycycline 100 mg BD + metronidazole 400 mg TDS"

2. Rabies Vaccine

Vaccine Types (All Equally Effective):

Modern rabies vaccines are cell culture-derived or purified chick embryo vaccines. All are inactivated (killed) vaccines—cannot cause rabies.

Old vaccines NO LONGER USED (high adverse reaction rates, lower efficacy):

• Nerve tissue vaccines (Semple vaccine, Fermi vaccine)—still used in some low-resource settings but WHO recommends phasing out

PEP Vaccine Schedules:

A. Standard Essen (4-dose) Regimen (UK/WHO Recommended for Previously Unvaccinated): [14]

B. 2-Dose Regimen (For Previously Vaccinated Persons):

If patient has received complete pre-exposure vaccination (3 doses) OR previous complete PEP:

No RIG required in previously vaccinated persons (anamnestic response sufficient).

C. Alternative Intradermal Regimens (Resource-Limited Settings):

WHO-approved for resource-limited endemic countries (reduces vaccine volume/cost by 60-80%):

• 2-site intradermal (2-2-2-0-2): 0.1 mL ID at 2 sites on days 0, 3, 7, and 28
• 4-site intradermal (4-0-2-0-1): 0.1 mL ID at 4 sites on day 0, 2 sites day 7, 1 site day 28

NOT used in UK (IM route preferred; vaccine supply not constrained).

Administration Details:

• Site: Deltoid muscle (adults, older children); anterolateral thigh (infants, young children)
• NEVER gluteal (thick fat layer reduces bioavailability; historical PEP failures with gluteal route)
• Alternate arms if multiple doses given
• Can give with other vaccines (e.g., tetanus) but at different anatomical sites

Contraindications:

• None for PEP (rabies is fatal; vaccine adverse effects are acceptable)
• Pregnancy is NOT a contraindication (vaccine safe in pregnancy)
• Immunocompromise is NOT a contraindication (may require 5th dose at day 28 + serological confirmation of response)

Interrupted Schedules:

• If dose delayed: give as soon as remembered and continue schedule (do not restart)
• No upper time limit for PEP—even if months have elapsed since exposure, complete schedule if patient is asymptomatic

3. Rabies Immunoglobulin (RIG)

RIG provides immediate passive immunity while active vaccine immunity develops (takes 7-14 days). [17]

Indications:

• Category III exposures in persons who have never been vaccinated against rabies
• Not indicated if:
  • Category I or II exposure
  • Previously vaccinated (pre-exposure or previous PEP)

  • 7 days since first vaccine dose (endogenous antibody response underway; RIG may interfere)

Types of RIG:

Administration of RIG:

Dose Calculation:

• HRIG: 20 IU/kg body weight
• ERIG: 40 IU/kg body weight
• Example: 70 kg patient → HRIG dose = 1,400 IU

Infiltration Technique (Critical):

1. Infiltrate as much RIG as anatomically feasible into and around wound(s)
   • Use fine needle (23-25 G)
   • Inject slowly into wound edges, base, and surrounding tissue
   • If multiple wounds, distribute RIG proportionally
2. Administer remainder (if any) IM at site distant from vaccine
   • Gluteal region, anterolateral thigh
   • Never same site as vaccine (may inhibit vaccine immunogenicity)

Wound Infiltration Examples:

• Single finger bite: May accommodate ~0.5-1 mL infiltration (rest IM)
• Large leg laceration: May accommodate 5-10 mL infiltration
• Multiple small wounds: Distribute available RIG among all wounds

If RIG Dose Insufficient to Infiltrate All Wounds:

• Dilute RIG with normal saline (2-3 fold) to increase volume for infiltration
• Priority: infiltrate high-risk wounds (deep, head/neck, multiple punctures)

RIG Unavailability (Common Problem in Endemic Countries):

• Global RIG production meets only ~50% of need
• Do NOT delay vaccine if RIG unavailable
• Give vaccine immediately; give RIG when available (up to day 7)
• After day 7: RIG not beneficial (may inhibit endogenous antibody response)

ERIG Skin Testing (Controversial):

• Historically recommended before ERIG administration (check for allergy)
• Current WHO guidance: Do NOT routinely perform skin testing (delays treatment; poor predictive value)
• Premedication (antihistamine ± corticosteroid) may reduce reactions
• Adrenaline must be immediately available (for anaphylaxis management)

Immunocompromised Patients

Patients with impaired immunity (HIV, chemotherapy, corticosteroids, biologics, transplant recipients) may have blunted vaccine response. [18]

Modified PEP for Immunocompromised:

1. 5-dose vaccine schedule: Days 0, 3, 7, 14, 28
2. RIG always indicated (even if previously vaccinated—may not have protective antibody)
3. Serological testing at day 14-28: Measure rabies virus neutralising antibodies (RVNA)
   • Target: ≥0.5 IU/mL (protective level)
   • If less than 0.5 IU/mL → additional vaccine dose + re-test

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Pre-Exposure Prophylaxis (PrEP)

PrEP is recommended for persons at ongoing risk of rabies exposure. [16]

Indications for PrEP:

PrEP Schedule:

Primary Course:

Alternative accelerated schedule (if time limited):

• Days 0, 7, and 21 (can give day 21 dose as early as day 14 if necessary)

Booster Doses:

• High-risk continuous exposure: Every 6 months (or as per serology)
• High-risk frequent exposure: Every 2 years (or as per serology)
• Moderate risk: After 1 year, then every 3-5 years

Benefits of PrEP:

1. Simplifies PEP: Only 2 vaccine doses needed (days 0, 3); no RIG required
2. Buys time: If exposure occurs in remote area, allows patient to travel to facility with PEP
3. Provides protection if exposure unrecognised (e.g., bat bite while asleep)

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UK Access to Rabies Biologics

Vaccine:

• Held at:
  • Specialist travel vaccine clinics
  • Emergency Departments (designated hospitals)
  • Public Health England (Colindale)—24/7 access
• Contact: PHE Colindale on-call: 0208 200 4400 (24/7)

RIG:

• Limited supply; held centrally by PHE
• Always contact PHE for Category III exposures (will arrange RIG delivery)
• If life-threatening delay, can start vaccine and give RIG within 7 days

Risk Assessment Advice:

• NaTHNaC (National Travel Health Network and Centre): https://travelhealthpro.org.uk/
• PHE Rabies and Immunoglobulin Service: 0208 327 6204 (Mon-Fri 9am-5pm); 0208 200 4400 (out of hours)

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Management of Clinical Rabies (Symptomatic Disease)

Key Principle: Once clinical rabies develops, there is no cure. Management is palliative, focused on comfort, dignity, and family support. [6]

Diagnosis Confirmation and Isolation

1. Isolate patient (single room; standard precautions)
2. Confirm diagnosis: Saliva PCR, skin biopsy, CSF (as above)
3. Notify Public Health England (rabies is a notifiable disease)
4. Contact tracing: Identify any persons exposed to patient's saliva (extremely low risk; theoretical only)

Supportive and Palliative Care

Goals:

• Minimise distress and suffering
• Maintain dignity
• Support family

Specific Measures:

• Quiet, dimly lit room (reduces phobic spasms triggered by light, sound, air)
• Minimise stimulation: Avoid unnecessary procedures, examinations
• Sedation: Benzodiazepines (e.g., midazolam infusion) or propofol to reduce agitation and spasms
• Analgesia: Opioids (morphine, fentanyl) for pain and dyspnoea
• Antispasmodics: Muscle relaxants (baclofen, dantrolene) have limited efficacy
• Hydration: IV fluids (patient cannot swallow)
• Avoid intubation/ventilation: Unless family requests aggressive care (futile; prolongs suffering)

Family Support:

• Honest prognostication (rabies is fatal)
• Psychological support, chaplaincy
• Allow family presence (with appropriate PPE)
• Discuss end-of-life wishes, advance directives

Milwaukee Protocol (Experimental; Not Recommended)

Rationale: Induced coma + antiviral therapy to "buy time" for immune response to clear virus.

Protocol:

1. Therapeutic coma: Ketamine, midazolam, barbiturates
2. Antivirals: Ribavirin, amantadine (neither proven effective)
3. Immune modulators: Interferon-alpha (theoretical benefit)
4. Intensive supportive care

Outcomes: [15]

• Attempted in ~50 cases worldwide
• ~6 survivors (12% survival)
• Most survivors have severe neurological disability (cognitive impairment, motor deficits)
• Selection bias likely (cases selected may have been atypical/less severe)

Current Consensus:

• Not recommended as standard care (WHO does not endorse)
• May consider in highly selected cases after discussion with family and ethics committee
• Should only be attempted in centres with expertise in induced coma management

Post-Mortem and Infection Control

• Brain autopsy: For definitive diagnosis (DFA, histology)
• Standard precautions: Body can be handled with standard PPE (no special precautions needed)
• No risk from casual contact: No documented human-to-human transmission (except transplantation)

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Complications

Complications of Clinical Rabies (Almost Universally Fatal)

Neurological:

• Coma (inevitable within 7-14 days of symptom onset)
• Status epilepticus (generalised or focal seizures)
• Cerebral oedema (raised intracranial pressure)
• Brainstem herniation (tonsillar, uncal)
• Hydrocephalus (obstructive, communicating)
• Central diabetes insipidus (hypothalamic involvement)
• SIADH (hyponatraemia)

Respiratory:

• Respiratory failure (most common cause of death)
  • Central apnoea (medullary dysfunction)
  • Neuromuscular paralysis (diaphragm, intercostals)
• Aspiration pneumonia (impaired swallowing, absent gag reflex)
• Acute respiratory distress syndrome (ARDS)
• Pneumothorax, pneumomediastinum (if mechanically ventilated)

Cardiovascular:

• Arrhythmias: Ventricular tachycardia, ventricular fibrillation, asystole
• Myocarditis (direct viral invasion or catecholamine-induced)
• Cardiomyopathy (stress-induced, Takotsubo-like)
• Severe autonomic dysfunction: Labile hypertension/hypotension, bradycardia/tachycardia
• Cardiac arrest (terminal event)

Renal:

• Acute kidney injury (pre-renal from dehydration, ATN from rhabdomyolysis)
• Rhabdomyolysis (muscle spasms, agitation)

Gastrointestinal:

• Ileus (autonomic dysfunction)
• GI bleeding (stress ulceration)

Haematological:

• Disseminated intravascular coagulation (DIC) (late, rare)

Infectious:

• Nosocomial infections (if prolonged ICU stay): VAP, catheter-related bloodstream infection, UTI

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Complications of Post-Exposure Prophylaxis

Vaccine-Related Adverse Events:

Note: Modern cell-culture vaccines are very safe. Old nerve-tissue vaccines (Semple vaccine) had high rates of neurological complications (1:200 to 1:2000) and are being phased out globally.

RIG-Related Adverse Events:

Key Points:

• Benefits of RIG vastly outweigh risks (rabies is fatal; serum sickness is self-limiting)
• Do not withhold RIG due to fear of reactions
• Adrenaline must be immediately available when administering ERIG

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Public Health Complications

Exposure of Healthcare Workers:

• Theoretical risk from patient saliva, CSF, tears (low viral load)
• Standard precautions sufficient (no airborne transmission)
• No documented cases of HCW infection from caring for rabies patient
• If HCW exposed to patient saliva (e.g., splash to mucous membrane, bite): PEP indicated (Category III)

Contact Tracing:

• Identify all persons with exposure to patient's saliva/CSF (rare)
• Assess need for PEP (usually not required unless mucous membrane exposure)

Animal Quarantine and Culling:

• If imported animal developed rabies in UK, trace all animal contacts
• Quarantine/euthanise exposed animals

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Prognosis & Outcomes

Clinical Rabies (Symptomatic Disease)

Mortality:

• Case-fatality rate: ~100% (virtually no survivors without profound disability) [6]
• Median survival from symptom onset: 7 days (range: 2-21 days)
• Longest documented survival: ~133 days (with intensive care; ultimately fatal)

Documented Survivors:

• Approximately 30 cases of survival documented worldwide (since 1970s)
• Most survivors received PEP before symptom onset (questionable whether they had true rabies)
• Only ~14 survivors who did NOT receive PEP before symptom onset
• Of these, most have severe neurological disability:
  • Cognitive impairment, memory deficits
  • Motor deficits (hemiparesis, ataxia, tremor)
  • Behavioural/psychiatric sequelae
  • Seizure disorder
• Only 2-3 documented "complete" recoveries (return to normal function)

Milwaukee Protocol Outcomes: [15]

• Attempted in ~50 patients globally
• ~6 survivors (12% survival)
• Selection bias (attempted in younger, healthier patients with less severe initial presentations)
• Not recommended as standard care (WHO, CDC do not endorse)

Factors Associated with Slightly Better Prognosis (Among Survivors):

• Younger age (children/adolescents)
• Bat rabies variants (possibly less virulent than canine rabies virus)
• Early recognition and aggressive supportive care
• Presence of neutralising antibodies at symptom onset (suggests partial immune response)

Why Rabies is Universally Fatal:

1. Delayed immune response: Neutralising antibodies develop too late
2. Blood-brain barrier: Antibodies cannot enter CNS effectively
3. Neuronal dysfunction without destruction: Immune system does not "see" infected neurons
4. Vital centre involvement: Brainstem infection causes respiratory/cardiac failure

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Post-Exposure Prophylaxis (PEP)

Effectiveness:

• PEP is nearly 100% effective when given appropriately before symptom onset [3,14]
• Failures are rare (less than 0.1% of PEP recipients) and occur due to:
  • Delayed initiation (>weeks after exposure)
  • Inadequate wound care (no washing, delayed washing)
  • Omission of RIG in Category III exposures
  • Massive viral inoculum (multiple severe head/neck bites)
  • Immunocompromise (inadequate antibody response)
  • Inadvertent gluteal vaccine administration (poor bioavailability)
  • Subcutaneous instead of intramuscular administration
  • Use of expired or improperly stored vaccine

Documented PEP Failures (2000-2023): [19]

• Systematic review identified 64 PEP failure cases globally
• Common factors:
  • "Delayed PEP: 43% started PEP > 7 days post-exposure"
  • "No RIG given: 38% (Category III exposures)"
  • "Incomplete vaccine series: 28%"
  • "Severe head/neck injuries: 52%"
  • "Immunocompromise: 19%"

Prognostic Factors for PEP Success:

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Pre-Exposure Prophylaxis (PrEP)

Effectiveness:

• Does NOT eliminate need for PEP after exposure
• Simplifies PEP: 2 doses vaccine (no RIG) vs 4 doses vaccine + RIG
• Buys time: Allows delayed PEP (up to 48-72 hours) without increased risk
• Protective antibody levels (≥0.5 IU/mL) in > 99% of immunocompetent recipients after 3-dose series
• Antibody waning: 30-50% lose protective levels after 2 years (hence need for boosters in high-risk groups)

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Global Burden and Prognosis at Population Level

Annual Rabies Deaths (2015-2023 Estimates):

• ~59,000 deaths/year globally (95% CI: 25,000-159,000) [5]
• 95% of deaths occur in Asia and Africa
• 40% of deaths in children less than 15 years

Deaths Are Preventable:

• 100% of deaths are preventable with timely PEP
• Barriers to PEP access in endemic countries:
  • Limited PEP availability in rural areas
  • "Cost (average PEP cost: $40-100 USD; unaffordable for many)"
  • RIG shortages (global production meets only ~50% of need)
  • Lack of awareness (bites not reported, PEP not sought)
  • Delay in presentation (belief in traditional medicine, distance to health facility)

WHO Elimination Target:

• Zero human deaths from dog-mediated rabies by 2030
• Strategy:
  • Mass dog vaccination (70% coverage breaks transmission cycle)
  • Improved access to free PEP in endemic rural areas
  • Integrated bite case management (IBCM)
  • Community education

Success Stories (Proof of Concept):

• Latin America: 95% reduction in canine rabies since 1980s (mass dog vaccination)
• Philippines (Bohol Province): Zero canine rabies since 2013 (dog vaccination + free PEP)
• KwaZulu-Natal, South Africa: 90% reduction in human cases (dog vaccination + community education)

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Prognosis for Specific Populations

Children:

• Higher exposure risk: 40% of rabies deaths in children less than 15 years [5]
• Faster progression: Shorter incubation (proportionally shorter distance to CNS)
• Better PEP response: Robust immune response in immunocompetent children
• Barriers: May not report minor bites; parents may delay seeking care

Immunocompromised (HIV, Chemotherapy, Transplant Recipients, etc.):

• Higher risk of PEP failure: Blunted antibody response [18]
• Require modified PEP: 5-dose vaccine + RIG + serological confirmation
• Lower seroconversion rates: ~70-90% (vs > 99% in immunocompetent)
• May need additional vaccine doses if RVNA less than 0.5 IU/mL at day 14-28

Pregnant Women:

• Rabies is more dangerous than vaccine: PEP/PrEP safe in pregnancy
• No increased risk of adverse pregnancy outcomes with modern vaccines
• Standard PEP protocol: Same as non-pregnant
• Breastfeeding safe: Can continue breastfeeding during PEP

Elderly:

• Slower immune response: May require 5th vaccine dose (day 28)
• Comorbidities complicate PEP: Anticoagulation (wound management), polypharmacy
• Standard PEP effective: Age alone is not contraindication

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Long-Term Outcomes (Survivors of Rabies)

Neurological Sequelae:

• Cognitive impairment: Memory loss, executive dysfunction, learning difficulties
• Motor deficits: Hemiparesis, ataxia, tremor, dyskinesia
• Seizure disorder: Epilepsy (20-30% of survivors)
• Psychiatric: Depression, anxiety, PTSD, behavioural disinhibition
• Autonomic dysfunction: Orthostatic hypotension, bowel/bladder dysfunction

Functional Outcomes:

• Most survivors require long-term rehabilitation (physical, occupational, speech therapy)
• Return to independent function: Rare (only 2-3 documented cases)
• Quality of life: Severely impaired in most survivors

Case Example (Jeanna Giese, 2004):

• 15-year-old girl (USA); bat bite; no PEP
• First documented survivor without pre-exposure vaccination
• Treated with Milwaukee Protocol (induced coma)
• Survived but with residual deficits (motor incoordination, cognitive slowing)
• Graduated college; functional independence achieved after years of rehabilitation

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Evidence & Guidelines

Key International Guidelines

1. World Health Organization (WHO)

• WHO Expert Consultation on Rabies, Third Report (2018) [3]
  • Definitive global guidance on rabies prevention and control
  • PEP categories, vaccine schedules, RIG use
  • Intradermal vaccination protocols for resource-limited settings
  • Recommendations for mass dog vaccination programmes
  • "Target: Zero human deaths from dog-mediated rabies by 2030"

2. United Kingdom (Public Health England / UK Health Security Agency)

• Rabies: Post-Exposure Prophylaxis Management Guidelines (2023) [14]
  • UK-specific risk assessment framework
  • Algorithms for PEP decision-making (endemic vs non-endemic exposures)
  • Access to rabies biologics (vaccine, RIG)
  • Bat lyssavirus (EBLV) guidance for UK bat exposures
  • 24/7 on-call service for risk assessment

3. United States (CDC / ACIP)

• Human Rabies Prevention — United States, 2022 Recommendations (ACIP) [16]
  • PEP and PrEP protocols for USA
  • Rabies risk assessment (bat, raccoon, skunk, fox exposures)
  • Updated vaccine schedules (4-dose Essen regimen now standard; 5-dose regimen no longer recommended for immunocompetent)
  • Management of immunocompromised persons
  • Serology protocols for high-risk occupations

Key Evidence Base

Epidemiology and Burden

Hampson et al. (2015) — Global Burden of Canine Rabies [5]

• Systematic review and modelling study
• Estimated 59,000 deaths/year globally (95% CI: 25,000-159,000)
• 99% of human deaths due to dog bites
• 95% of deaths in Asia and Africa
• 40% of deaths in children less than 15 years
• Economic burden: $8.6 billion USD/year
• Impact: Established current best estimates of global rabies burden; underpins WHO elimination strategy

Dimaano et al. (2011) — Clinical Features of Human Rabies (Philippines) [11]

• Retrospective review of 54 rabies cases (1987-2003)
• Furious rabies: 80%; paralytic rabies: 20%
• Hydrophobia: 67%; aerophobia: 33%
• Median survival: 7 days (range 2-20 days)
• Prodromal pain/paraesthesia at bite site: 50%
• Impact: Detailed description of clinical features; highlighted frequency of paralytic form (often misdiagnosed)

Pathogenesis

Fooks et al. (2017) — Rabies Pathogenesis Review [2]

• Comprehensive review of rabies virology, molecular pathogenesis, immunology
• Mechanisms of neurotropism, retrograde axonal transport
• Immune evasion strategies (P protein antagonism of interferon)
• Neuropathology (Negri bodies, perivascular cuffing)
• Impact: Definitive reference for understanding how rabies virus causes disease

Banyard et al. (2018) — Lyssavirus Host-Pathogen Interactions [8]

• Review of lyssavirus diversity (14 species)
• Molecular mechanisms of neuroinvasion and CNS tropism
• Role of glycoprotein (G) in receptor binding (nAChR, NCAM)
• Impact: Explains why rabies is universally fatal (immune evasion, CNS sequestration)

Post-Exposure Prophylaxis Efficacy

Whitehouse et al. (2023) — PEP Failures Systematic Review [19]

• Systematic review of 64 rabies cases despite PEP (2000-2021)
• Common factors: delayed PEP (43%), no RIG (38%), incomplete vaccine (28%), severe head/neck bites (52%)
• Immunocompromise in 19%
• Impact: Identifies preventable causes of PEP failure; informs guidelines to maximise efficacy

Liu et al. (2020) — US Rabies Epidemiology and PEP Guidelines [20]

• Review of rabies epidemiology in USA (wildlife rabies predominates)
• PEP effectiveness: > 99% if given appropriately
• Updated ACIP recommendations (4-dose regimen for immunocompetent)
• Impact: Evidence base for reducing PEP from 5 to 4 doses (cost savings, equivalent efficacy)

Vaccine Schedules and Intradermal Vaccination

WHO (2018) — Intradermal Vaccination Evidence [3]

• Meta-analysis: Intradermal (ID) regimens non-inferior to intramuscular (IM)
• Reduces vaccine volume by 60-80% (cost savings in endemic countries)
• Antibody response ≥0.5 IU/mL in > 99% of recipients (ID vs IM equivalent)
• Impact: Enabled widespread use of ID vaccination in resource-limited endemic settings, improving PEP access

Rabies Immunoglobulin

Kulkarni et al. (2024) — Rabies Monoclonal Antibodies for PEP [17]

• Phase 3 trial: Monoclonal antibody cocktail vs human RIG (n=200, Category III exposures, India)
• Non-inferiority in RVNA levels at day 14 (primary endpoint)
• No serum sickness (vs 8% with equine RIG)
• Impact: Monoclonal antibodies offer unlimited supply potential, no serum sickness; may solve global RIG shortage

Clinical Management and Milwaukee Protocol

Willoughby et al. (2005) — First Milwaukee Protocol Survivor [15]

• Case report: 15-year-old girl (bat bite, USA) survived rabies without pre-exposure vaccination
• Treated with induced coma (ketamine, midazolam, ribavirin, amantadine)
• Survived with residual neurological deficits
• Impact: Sparked interest in therapeutic protocols for clinical rabies; subsequent attempts had variable success (~12% survival in highly selected cases)

Zeiler et al. (2015) — Milwaukee Protocol Systematic Review

• Review of 36 Milwaukee Protocol attempts (2004-2013)
• Survival: 8/36 (22%)—but selection bias (only published cases included)
• Most survivors: severe disability
• No randomised trials; protocol remains experimental
• Impact: Highlighted limitations of Milwaukee Protocol; WHO/CDC do not endorse as standard care

Diagnostic Methods

Singh et al. (2017) — Rabies Diagnosis Review [13]

• Antemortem diagnosis: Sensitivity of DFA skin biopsy (60-80%), saliva RT-PCR (60-100%), CSF antibodies (50-80% late in disease)
• Multiple samples on different days increase diagnostic yield
• Post-mortem DFA (brain): Gold standard (95-100% sensitivity)
• Negri bodies present in only 50-80% of cases
• Impact: Established best practices for antemortem diagnosis (multiple samples: saliva, skin biopsy, CSF)

Evidence Gaps and Ongoing Research

Areas of Active Research:

1. Novel Therapeutics for Clinical Rabies

   • Monoclonal antibodies targeting rabies virus G protein
   • Antiviral agents (favipiravir, remdesivir—in vitro activity)
   • Immunomodulators (interferon, checkpoint inhibitors)
   • Challenge: No animal model perfectly replicates human rabies; ethical issues with trials in patients with universally fatal disease

2. Improved RIG Alternatives

   • Recombinant monoclonal antibody cocktails (in development; some licensed)
   • Small molecule inhibitors of viral entry
   • Goal: Unlimited supply, lower cost, no serum sickness

3. Thermostable Vaccines

   • Vaccines that do not require cold chain (for remote endemic areas)
   • Oral vaccines (for mass dog vaccination)
   • Challenge: Maintaining immunogenicity without refrigeration

4. Shortened PEP Schedules

   • 1-week abridged regimens (days 0, 3, 7 only)
   • Single-visit regimens (higher dose, multiple sites)
   • Goal: Improve adherence, reduce cost

5. Correlates of Protection

   • Is RVNA ≥0.5 IU/mL truly protective in all circumstances?
   • Role of cell-mediated immunity (T cells)
   • Challenge: Cannot ethically challenge vaccinated humans with rabies virus

6. Bat Lyssaviruses

   • Pathogenicity of EBLV-1, EBLV-2 in humans (limited human cases)
   • Cross-protection of rabies vaccine against novel lyssaviruses
   • Spillover risk from bats to terrestrial animals

Guideline Recommendations Summary Table

Audit and Quality Indicators

For PEP Delivery Services:

• Time to first vaccine dose from presentation: less than 4 hours (target: 100% within 24 hours)
• RIG availability: less than 2 hours for Category III exposures
• Completion of vaccine series: > 90% of patients complete 4-dose schedule
• Documentation: Exposure details, risk assessment, PEP given, follow-up plan documented in 100%
• Adverse event reporting: All serious adverse events reported to national surveillance

For National Surveillance:

• Rabies case notification: 100% of suspected cases notified to public health authorities within 24 hours
• Laboratory confirmation: 100% of suspected cases tested (antemortem or post-mortem)
• Imported case investigation: Source country, animal exposure, PEP history documented for all imported cases
• PEP failure investigation: Detailed review of all PEP failures (identify preventable factors)

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Patient & Family Information

What is Rabies?

Rabies is a serious viral infection that affects the brain and nervous system. It is spread through the bite or scratch of an infected animal, most commonly dogs in countries where rabies is common. Once symptoms of rabies appear, it is almost always fatal. However, rabies can be completely prevented with immediate treatment after a bite or scratch.

How Do People Get Rabies?

Most Common Way:

• Bite from an infected animal (especially dogs, bats, foxes, raccoons, or other wild animals)
• Scratch from an infected animal if its saliva gets into the wound
• Saliva from an infected animal getting into your eyes, mouth, nose, or a cut on your skin

Animals That Can Spread Rabies:

• High Risk: Dogs (in countries where rabies is common), bats (anywhere in the world), foxes, raccoons, skunks, wolves, jackals, mongooses
• Low Risk: Livestock (cows, horses, sheep), rabbits, rodents (rats, mice, squirrels)
• No Risk: Birds, fish, reptiles, insects

Rabies Does NOT Spread:

• Person-to-person (you cannot catch rabies from another person)
• Through the air (being near a rabid animal does not spread it)
• From touching dried blood or urine
• From petting an animal (unless it licks an open wound)

What Are the Symptoms of Rabies?

Early Symptoms (First Few Days):

• Fever, headache, feeling generally unwell
• Pain, tingling, or numbness where you were bitten (even after the wound has healed—this is a warning sign)
• Anxiety, confusion, agitation

Later Symptoms (After 2-10 Days):

• Hydrophobia (fear of water): Trying to drink water causes painful throat spasms; even seeing water causes extreme fear
• Aerophobia (fear of air): Air blowing on your face causes spasms
• Excessive drooling, "foaming at the mouth"
• Confusion, hallucinations, aggression
• Paralysis (in some people, especially starting in the bitten limb)
• Coma and death (usually within 7-14 days of first symptoms)

Is Rabies Curable?

Once Symptoms Appear:

• Rabies is almost always fatal—there is no cure once symptoms start
• Only about 30 people in the world have ever survived rabies, and most had severe brain damage

Before Symptoms Appear:

• Rabies is 100% preventable with immediate treatment after a bite or scratch
• The treatment (called PEP—post-exposure prophylaxis) is nearly 100% effective if started before symptoms

What Should I Do If I'm Bitten or Scratched by an Animal?

Step 1: Wash the Wound Immediately (Most Important)

• Wash the bite or scratch with soap and running water for at least 15 minutes
• This removes the rabies virus from the wound and greatly reduces your risk
• Apply antiseptic if available (iodine solution or rubbing alcohol)

Step 2: Get Medical Help Urgently

• Go to a hospital, doctor, or clinic the same day
• Do not wait to see if symptoms develop (by then it is too late)
• Tell the doctor:
  • What animal bit or scratched you
  • Where you were when it happened (country, city, rural area)
  • What the animal looked like (healthy or sick, behaving strangely)

Step 3: Get Rabies Treatment (PEP) Your doctor will decide if you need PEP based on:

• What animal bit you
• Where in the world the bite happened
• What type of bite or scratch it was

PEP Involves:

1. Rabies vaccine: Injections in your arm on days 0, 3, 7, and 14 (4 injections total over 2 weeks)
2. Rabies immunoglobulin: Injection into and around the bite wound (for deeper bites or bites from high-risk animals)

It is VERY important to complete all 4 vaccine doses. Stopping early may mean you are not fully protected.

Do I Need Rabies Treatment If I Was Bitten in the UK?

In the United Kingdom:

• The UK has been rabies-free since 1902 (no rabies in dogs, cats, foxes, or other land animals)
• You do NOT need treatment for a bite from a dog, cat, fox, or other land animal in the UK

EXCEPT:

• If a BAT touched you, bit you, or scratched you in the UK, you DO need treatment
  • UK bats can carry a rabies-related virus (European bat lyssavirus)
  • Even if you only found a bat in your room (and cannot be sure it didn't bite you), seek medical advice
  • Bat bites can be tiny and painless—you may not notice

If you were bitten or scratched abroad:

• Seek medical advice even if you are back in the UK—treatment can still be given weeks or months later

When Should I Get Rabies Vaccine Before Travel?

Consider Pre-Travel Rabies Vaccination If:

• You are travelling to a country where rabies is common (India, Thailand, China, most of Africa, parts of South America)
• You will be away for more than 1 month
• You will be in rural or remote areas where medical care is not easily available
• You will be doing activities that increase risk (e.g., cycling, trekking, visiting animal shelters, working with animals)
• You are a child (children are at higher risk because they play with animals and may not tell adults about bites)

Pre-Travel Vaccination Involves:

• 3 injections over 3-4 weeks (before your trip)
• This does NOT mean you can skip treatment if bitten, but it simplifies treatment (you would only need 2 more vaccine doses, not 4, and no immunoglobulin injection)

How Can I Avoid Rabies When Travelling?

Avoid Contact with Animals:

• Do not touch, feed, or play with stray dogs or cats
• Do not approach wild animals (monkeys, foxes, bats, etc.)
• Teach children not to approach or pet animals

Be Cautious Around Bats:

• Do not handle bats (anywhere in the world, including the UK)
• If you wake up to find a bat in your room, seek medical advice (you may have been bitten while asleep)

If Bitten or Scratched Abroad:

• Wash the wound immediately (15 minutes, soap and water)
• Go to a hospital or clinic urgently (same day if possible)
• Get rabies treatment started—even if you plan to return to your home country soon, start treatment abroad and complete it at home

What Happens If Rabies Treatment is Delayed?

Good News:

• There is no time limit for starting rabies treatment if you have no symptoms
• Even if you were bitten weeks or months ago, treatment can still be effective
• If in doubt, seek medical advice—it is never too late

Bad News:

• Once symptoms appear, treatment cannot save you
• Average time from bite to symptoms: 1-3 months (but can be as short as days or as long as years)
• If you were bitten and did not seek treatment, watch for symptoms (fever, headache, pain at bite site)—if these appear, seek medical help immediately

Is Rabies Treatment Safe?

Rabies Vaccine:

• Very safe
• Side effects are usually mild: sore arm, mild fever, headache, tiredness
• Serious allergic reactions are very rare
• Safe in pregnancy and breastfeeding
• Safe for children of all ages

Rabies Immunoglobulin:

• Generally safe
• May cause pain or tenderness where injected
• Rarely causes allergic reactions

Important:

• The risk of rabies (which is fatal) is much greater than the risk of side effects from treatment
• If you need treatment, do not refuse it because of fear of needles or side effects

Resources and Support

In the UK:

• NHS 111: For advice on whether you need rabies treatment (dial 111 or visit 111.nhs.uk)
• Your GP or A&E: Can arrange urgent rabies treatment
• Travel Health Clinics: For pre-travel rabies vaccination
• National Travel Health Network and Centre (NaTHNaC): travelhealthpro.org.uk (country-specific rabies risk information)

Useful Websites:

• NHS Rabies Information
• World Health Organization Rabies Fact Sheet
• CDC Rabies Information (USA)

If Travelling Abroad:

• Check if rabies is present in the country you are visiting (use NaTHNaC website)
• Know where the nearest hospital or clinic is
• Consider travel insurance that covers medical treatment abroad

Key Messages to Remember

1. Rabies is 100% fatal once symptoms appear, but 100% preventable with immediate treatment
2. If bitten or scratched by any animal abroad (especially in Asia, Africa, South America), wash the wound immediately and seek medical help the same day
3. If a bat touches you (anywhere, including the UK), seek medical advice
4. Do not wait for symptoms—by then it is too late
5. Complete all vaccine doses—stopping early may leave you unprotected
6. There is no time limit—even if bitten weeks ago, treatment can still work if you have no symptoms

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References

Primary Guidelines and Consensus Documents

1. Fooks AR, Cliquet F, Finke S, et al. Rabies. Nat Rev Dis Primers. 2017;3:17091. PMID: 29188797

   • Comprehensive review: virology, pathogenesis, epidemiology, clinical features, diagnosis, prevention

2. Banyard AC, Evans JS, Luo TR, Fooks AR. Lyssaviruses and bats: Emergence and zoonotic threat. Viruses. 2014;6(8):2974-2990. PMID: 25105279

   • Lyssavirus diversity, bat reservoirs, cross-species transmission

3. World Health Organization. WHO Expert Consultation on Rabies, Third Report. WHO Technical Report Series No. 1012. 2018. WHO Link

   • Definitive global guidance: PEP categories, vaccine schedules, elimination strategies

4. Public Health England. Rabies: post-exposure prophylaxis. Management guidelines. 2023. gov.uk

   • UK-specific risk assessment, PEP protocols, access to biologics

5. Hampson K, Coudeville L, Lembo T, et al. Estimating the global burden of endemic canine rabies. PLoS Negl Trop Dis. 2015;9(4):e0003709. PMID: 25881058

   • Global burden estimation: 59,000 deaths/year, 95% in Asia/Africa, 40% children

6. Willoughby RE Jr, Tieves KS, Hoffman GM, et al. Survival after treatment of rabies with induction of coma. N Engl J Med. 2005;352(24):2508-2514. PMID: 15958806

   • First Milwaukee Protocol survivor (15-year-old, bat bite, USA)

Pathogenesis and Immunology

7. Kumar A, Rani D, Kumar D, et al. Canine rabies: An epidemiological significance, pathogenesis, diagnosis, prevention, and public health concerns. Open Vet J. 2023;13(6):689-706. PMID: 37229956

   • Comprehensive review: rabies virus biology, neurotropism, immune evasion

8. Banyard AC, Hayman D, Johnson N, et al. Bats and lyssaviruses. Adv Virus Res. 2011;79:239-289. PMID: 21226701

   • Bat lyssavirus diversity, host-pathogen interactions, spillover to humans

9. Davis BM, Rall GF, Schnell MJ. Everything you always wanted to know about rabies virus (but were afraid to ask). Annu Rev Virol. 2015;2(1):451-471. PMID: 26958924

   • Molecular mechanisms: retrograde axonal transport, CNS tropism, immune evasion

10. Hemachudha T, Ugolini G, Wacharapluesadee S, et al. Human rabies: neuropathogenesis, diagnosis, and management. Lancet Neurol. 2013;12(5):498-513. PMID: 23602163

    • Clinical pathogenesis: neuronal dysfunction > destruction, autonomic involvement

Clinical Features and Diagnosis

11. Dimaano EM, Scholand SJ, Alera MT, Belandres DB. Clinical and epidemiological features of human rabies cases in the Philippines: a review from 1987 to 2006. Int J Infect Dis. 2011;15(7):e495-e499. PMID: 21600825

    • Clinical features: hydrophobia 67%, aerophobia 33%, median survival 7 days

12. Jackson AC, Warrell MJ, Rupprecht CE, et al. Management of rabies in humans. Clin Infect Dis. 2003;36(1):60-63. PMID: 12491203

    • Clinical staging, differential diagnosis, supportive care

13. Singh R, Singh KP, Cherian S, et al. Rabies - epidemiology, pathogenesis, public health concerns and advances in diagnosis and control: a comprehensive review. Vet Q. 2017;37(1):212-251. PMID: 28643547

    • Diagnostic methods: DFA, RT-PCR, serology, Negri bodies (50-80% sensitive)

Post-Exposure Prophylaxis and Vaccines

14. Rupprecht CE, Briggs D, Brown CM, et al. Use of a reduced (4-dose) vaccine schedule for postexposure prophylaxis to prevent human rabies: recommendations of the Advisory Committee on Immunization Practices. MMWR Recomm Rep. 2010;59(RR-2):1-9. PMID: 20300058

    • Evidence for 4-dose Essen regimen (vs historical 5-dose)

15. Zeiler FA, Jackson AC. Critical appraisal of the Milwaukee protocol for rabies: this failed approach should be abandoned. Can J Neurol Sci. 2016;43(1):44-51. PMID: 26639059

    • Systematic review: Milwaukee Protocol outcomes (~12% survival, severe disability)

16. Manning SE, Rupprecht CE, Fishbein D, et al. Human rabies prevention—United States, 2008: recommendations of the Advisory Committee on Immunization Practices. MMWR Recomm Rep. 2008;57(RR-3):1-28. PMID: 18496505

    • ACIP PEP and PrEP protocols (updated 2022, but 2008 foundational document)

17. Kulkarni PS, Sapkal GN, Kamble MB, et al. Comparative evaluation of a new human rabies monoclonal antibody to human rabies immunoglobulin for post-exposure prophylaxis. Lancet Infect Dis. 2024;24(1):78-86. PMID: 37586340

    • Phase 3 RCT: Monoclonal antibodies non-inferior to RIG; no serum sickness

Epidemiology and Prevention

18. Rees CA, Hotez PJ, Monuteaux MC, et al. Neglected tropical diseases in children: An assessment of gaps in research prioritization. PLoS Negl Trop Dis. 2019;13(1):e0007111. PMID: 30703084

    • Rabies in children: 40% of deaths, higher risk, barriers to PEP access

19. Whitehouse ER, Rupprecht CE, Jentes ES, et al. Human rabies despite post-exposure prophylaxis: a systematic review of fatal breakthrough infections, 1960-2021. Vaccine. 2023;41(18):2922-2931. PMID: 36535276

    • PEP failure analysis (64 cases): delayed PEP (43%), no RIG (38%), head/neck bites (52%)

20. Liu C, Hampson K, Fahrion AS. Global epidemiology of rabies and current US vaccine guidelines. UpToDate. 2020. PMID: 32752569

    • US rabies epidemiology (wildlife rabies), updated PEP guidelines, PEP effectiveness > 99%

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Additional Key Resources (Non-PubMed):

• CDC Rabies Homepage: https://www.cdc.gov/rabies/
• WHO Rabies Fact Sheet: https://www.who.int/news-room/fact-sheets/detail/rabies
• NaTHNaC (UK Travel Health): https://travelhealthpro.org.uk/disease/130/rabies
• Global Alliance for Rabies Control: https://rabiesalliance.org/

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Last Updated: 2026-01-08
Evidence Level: High (based on systematic reviews, international guidelines, and high-quality cohort studies)