Mumps — formative SAQs

SAQ 1 (10 marks)

A 16-year-old boy presents with three days of fever, malaise and progressive bilateral tender parotid swelling, and today with severe right testicular pain and swelling. He received two MMR doses as a child and has just started university, where a mumps outbreak is circulating. On examination the right testis is swollen and tender; the parotid swelling is classic. [5]

Question: Outline the immediate and stepwise management of this adolescent, including the acute scrotal-pain assessment, supportive care, diagnosis, infection control and the public-health response. (10 marks) [4]

Model answer

Acute scrotal-pain assessment (2 marks). The immediate priority is to exclude testicular torsion, a time-critical surgical emergency, because mumps orchitis and torsion can overlap. The history (sudden onset, severe pain, absent cremasteric reflex, high-riding testis) and the timing relative to parotitis matter, but whenever torsion is plausible the safest stance is urgent surgical assessment rather than attributing the pain to mumps. Torsion missed is devastating and avoidable. [5]

Diagnosis (2 marks). Send a buccal or oral swab for mumps RT-PCR, which has its highest yield in the first one to three days of parotitis, and supplement with mumps IgM and IgG serology. In a previously vaccinated individual IgM may be blunted, so PCR with genotyping (to confirm wild-type rather than vaccine strain) is the most informative approach. Do not delay supportive care or isolation while waiting for results. [6]

Supportive care (2 marks). There is no antiviral, antibiotic or corticosteroid of proven benefit in mumps; management is supportive. Provide analgesia and antipyretics (paracetamol or ibuprofen), hydration, a soft diet that does not stimulate painful salivation, and scrotal support and rest for the orchitis. Admit for pain control if needed, and give honest discussion of testicular atrophy (possible) and sterility (rare). [4]

Infection control (2 marks). Isolate with droplet precautions and exclude from university for five days from the onset of parotitis swelling, supported by the Kutty evidence review that justified the change from nine days. The five-day window reflects the sharp fall in infectiousness after the first days of parotitis. [3]

Public-health response (2 marks). Notify public health according to local requirements, because mumps is notifiable, and the notification triggers contact tracing and the outbreak-control response. Trace household and close contacts, identify who is susceptible (under-vaccinated, pregnant, immunocompromised), give catch-up MMR to the under-immunised, and — in this outbreak setting — offer a targeted third MMR dose to high-risk groups, for which the Cardemil study provides the evidence base. [1] [2]

SAQ 2 (10 marks)

Question: A 20-year-old university student who received two MMR doses in childhood presents during a mumps outbreak with fever, headache and unilateral parotid swelling of two days' duration. Her mumps IgM is negative. (a) What is the likely diagnosis and how will you confirm it, given the negative IgM? (b) Outline the supportive management and infection-control measures. (c) Explain why a two-dose-vaccinated young adult is still at risk, and how this informs outbreak control. (10 marks) [2]

Model answer

(a) Diagnosis and confirmation (3 marks). The likely diagnosis is mumps, despite the negative IgM. In a previously vaccinated individual the IgM response may be blunted or absent, so a negative IgM does not exclude mumps during an outbreak. Confirm with a buccal or oral swab for mumps RT-PCR, which has its highest yield in the first days of parotitis, and use viral genotyping to distinguish wild-type from vaccine strain. The diagnosis is built on the clinical picture, the outbreak epidemiology and PCR together, not on a single negative serological result. [6]

(b) Supportive management and infection control (4 marks). Management is supportive — analgesia and antipyretics, hydration, a soft diet — because there is no antiviral, antibiotic or steroid of proven benefit. Isolate with droplet precautions and exclude from university for five days from the onset of parotitis swelling, and notify public health to trigger contact tracing and the outbreak-control response. Trace household and close contacts and identify who is susceptible (under-vaccinated, pregnant, immunocompromised) for review. [4] [3]

(c) Why the vaccinated young adult is still at risk, and outbreak control (3 marks). Two doses of MMR are about 88% effective, but protection wanes over the years after the second dose, leaving older adolescents and young adults susceptible in dense settings such as universities — the Barskey Orthodox Jewish community outbreak and the French waning-immunity reports confirm this pattern. This is why mumps keeps recurring in vaccinated populations despite high coverage. Outbreak control therefore relies on more than two-dose priming: prompt isolation and notification, contact tracing, catch-up vaccination of the under-immunised, and a targeted third MMR dose for high-risk groups, for which the Cardemil study provides the evidence that a third dose improves outbreak control in this exact setting. [2] [1]