Hand-foot-and-mouth disease and enterovirus infection — formative SAQs

SAQ 1 (10 marks)

A 22-month-old boy is brought to the emergency department on day three of a febrile illness. He has classic hand-foot-and-mouth disease — painful oral ulcers and vesicles on the palms, soles and buttocks. Over the past twelve hours the parents have noticed brief jerks of his limbs during sleep and this morning he has been unsteady when trying to walk. He is febrile at 38.9°C, tachycardic at 150/min with a blood pressure of 118/76 mmHg, and intermittently irritable. [2]

Question: Outline the immediate and stepwise management of this child, including recognition of the complication, investigations, supportive and critical care, and the conversation with the family. (10 marks) [8]

Model answer

Recognition and disposition (2 marks). This child has enterovirus 71 brainstem encephalitis complicating HFMD. Sleep myoclonus and ataxia in a child with HFMD on day three are the classical early brainstem signs, and the tachycardia and borderline-high blood pressure raise concern for early autonomic dysregulation. Admit immediately to a monitored bed and alert the paediatric intensive care unit; the window between tremor and pulmonary oedema can be brief. [2] [5]

Investigations (2 marks). Send vesicle fluid, throat and stool PCR for enterovirus with EV71 subtyping — stool remains positive for weeks, while vesicle and throat samples are most sensitive while lesions are present. Arrange cerebrospinal fluid analysis after stabilisation (lymphocytic pleocytosis, possible EV71 PCR) and magnetic resonance imaging of brain and spine, which may show characteristic brainstem signal change. An N-terminal pro-B-type natriuretic peptide may be sent as a prognostic marker of cardiac strain. [5] [7]

Supportive and critical care (3 marks). Secure the airway and observe continuously for autonomic and respiratory deterioration. The haemodynamic strategy is specific: judicious fluid restriction with milrinone and vasoactive support to counter brainstem-driven sympathetic overdrive and vascular leak — avoid generous fluid boluses, which worsen pulmonary oedema. At the first sign of tachypnoea, desaturation or pulmonary oedema, ventilate with lung-protective settings and consider ECMO capability for refractory failure. State honestly that there is no proven antiviral and that intravenous immunoglobulin is used empirically on weak evidence. [7] [8]

Infection control and the family conversation (3 marks). Maintain contact and droplet precautions, and explain to the family that this is the dangerous end of a usually-mild illness — the same rash with a different virus. Discuss the possibility of deterioration and the rationale for intensive monitoring, while arranging childcare exclusion and household hand hygiene. Notify the case appropriately, and reinforce that prevention rests on hygiene because there is no routine EV71 vaccine in ANZ. Plan multidisciplinary rehabilitation for any persistent neurological deficit in survivors. [8] [2]

SAQ 2 (10 marks)

Question: You are the general paediatrician consulted about a cluster of eight hand-foot-and-mouth disease cases over two weeks in a single childcare room of children aged two to four. (a) What is the likely causative differential, and how will you establish which enterovirus is responsible and why does it matter? (b) Outline the outbreak management and infection-control response. (c) Explain the EV71 vaccine situation and how it shapes prevention in your region. (10 marks) [1]

Model answer

(a) Causative differential and why it matters (3 marks). The likely agents are coxsackievirus A16 (classic, usually mild), enterovirus 71 (neurotropic and potentially lethal) and coxsackievirus A6 (atypical, extensive rash with later onychomadesis). Establishing the strain matters because an EV71-dominant season carries a real risk of brainstem encephalitis and pulmonary oedema and lowers the threshold for admission and observation across the whole service, whereas a CVA16 season is largely benign. Confirm by arranging PCR with subtyping on throat swabs or stool from representative cases through the reference laboratory. [1] [2]

(b) Outbreak and infection-control management (4 marks). Notify the outbreak to the public-health unit and work with the childcare centre on exclusion of unwell children while they are febrile and until lesions have healed or are covered. Reinforce hand hygiene (alcohol-based gel does not fully eliminate enteroviruses, so soap-and-water handwashing is important), surface cleaning of shared toys and changing areas, and avoidance of sharing utensils. Counsel staff and parents on the red flags — poor feeding, drowsiness, weakness, unsteadiness or breathing difficulty — and on protecting the youngest household contacts, especially infants. Pregnant staff should be reassured with careful safety-netting. [1] [8]

(c) EV71 vaccine situation and prevention (3 marks). Two large phase-3 trials (Zhu and Li, New England Journal of Medicine 2014) showed that inactivated enterovirus 71 vaccines protect against EV71-associated HFMD and its neurological complications, and these vaccines are licensed and in use in China; the WHO, following the 2016 SAGE review, endorses their use in high-burden settings. However, the vaccines are not part of routine schedules in Australia, Aotearoa New Zealand, the UK, the US or Canada, and they do not cover coxsackieviruses, so a vaccinated child can still develop non-EV71 HFMD. In my region, prevention therefore rests on hygiene, childcare exclusion, outbreak surveillance and clinician vigilance for the EV71 neurological signs — not on routine vaccination. [8] [1]