On this page
Study tools
Write your answer
Saved on this device. No marking — you are the marker.
Q1: An 8-year-old unvaccinated boy presents with fever and bilateral tender parotid swelling. Discuss the diagnosis and its pathogen. (2 min)
This is the classic presentation of mumps (epidemic parotitis) — an acute, vaccine-preventable viral infection caused by the mumps virus, an enveloped, negative-sense single-stranded RNA virus of the Paramyxoviridae family, Rubulavirus genus. Humans are the only reservoir; transmission is by respiratory droplets, saliva and fomites, with peak infectivity from 2 days before to 5 days after parotitis onset. The incubation period is 16 to 18 days (range 12 to 25). Before vaccination, mumps was a near-universal childhood infection; in the post-vaccine era it shifts to adolescents and young adults in whom waning vaccine immunity drives outbreaks. The cardinal clinical sign is painful, nonsuppurative parotid swelling that lifts the ear lobe upwards and forwards and obliterates the angle of the mandible (bilateral in 70 percent, sequential). The diagnosis is clinical in the setting of classic parotitis with known exposure/outbreak; buccal-swab RT-PCR (preferred, especially in vaccinated) and/or mumps IgM confirm when atypical.
Q2: How would you confirm the diagnosis and why is the choice of test important in a vaccinated patient? (2 min)
Diagnosis is clinical when the picture is classic in a known outbreak; laboratory confirmation is required for sporadic, atypical, parotitis-negative, or institutional/outbreak cases. First-line: buccal-swab RT-PCR for mumps virus RNA — the preferred confirmatory test, most sensitive in the first 3 days of parotitis. PCR is also the test of choice in previously vaccinated people because the mumps IgM response may be absent, delayed or attenuated in them — a negative IgM does NOT exclude mumps in the vaccinated, and PCR becomes essential. Supporting tests: mumps IgM (single raised value suggests recent infection) and paired IgG (fourfold rise between acute and convalescent sera confirms). Viral culture is slower and less sensitive. Baseline tests include FBC (typically normal or mild lymphocytosis; leucocytosis suggests bacterial parotitis or complication) and serum amylase/lipase (raised in 30-50 percent from parotitis; disproportionate lipase suggests pancreatitis). Mumps is a notifiable disease — send samples to the reference laboratory for confirmation and genotyping.
Q3: What is your management, and what public-health action is mandatory? (2 min)
The mainstay is supportive care — there is NO specific antiviral of proven benefit. I would give rest, adequate hydration, a soft non-acidic diet (avoid acidic juices which aggravate parotid pain), analgesia/antipyretics — paracetamol 1 g every 6 hours (max 4 g/day; 15 mg/kg/dose in children) and/or ibuprofen 400 mg every 8 hours — and local measures (warm or cold compresses, salt-water gargles). The mandatory public-health action is to isolate the patient with droplet precautions and exclude him from school for 5 days AFTER the onset of parotid swelling (peak infectivity is 2 days before to 5 days after parotitis), to notify public health (mumps is notifiable), and to identify and vaccinate susceptible contacts (those with zero or one MMR dose should receive catch-up MMR). I would not give antivirals, antibiotics or routine corticosteroids — none is of benefit in uncomplicated mumps.
Q4: Discuss the complications of mumps and which you must specifically not miss. (3 min)
The complications — and the high-yield point is that they can occur WITHOUT parotitis — are: orchitis/oophoritis (post-pubertal; orchitis in 20 to 30 percent of post-pubertal males, usually unilateral; infertility is rare even when bilateral), aseptic meningitis (CSF pleocytosis in 50 to 60 percent even when asymptomatic; symptomatic meningitis in 1 to 10 percent; benign course), meningoencephalitis (~0.1 percent; seizures, coma, focal deficits; small mortality), pancreatitis (2 to 5 percent), sensorineural deafness (about 1 in 20,000; usually unilateral, sudden, often permanent — a leading acquired cause of unilateral childhood deafness where mumps is endemic), myocarditis (rare; usually mild), and arthritis, thyroiditis, mastitis, glomerulonephritis, thrombocytopenia. In pregnancy there is an increased rate of first-trimester miscarriage but no proven teratogenicity (unlike rubella).
Two complications I must specifically not miss: (1) testicular TORSION in any post-pubertal male with acute scrotum during mumps — I would exclude torsion FIRST with urgent Doppler ultrasound and urology review, and explore surgically if torsion cannot be excluded, because torsion is a surgical emergency and mumps orchitis is not. (2) Meningoencephalitis — in any patient with severe headache, neck stiffness, photophobia, seizures or depressed consciousness I would examine the CSF and, if uncertain, give empirical bacterial meningitis antibiotics (ceftriaxone 2 g IV 12-hourly) plus aciclovir 10 mg/kg IV 8-hourly until CSF excludes bacterial and HSV disease. The mnemonic I use for complications is OOMPH — Orchitis/Oophoritis, Other glandular (pancreatitis), Meningitis/Meningoencephalitis, Parotitis, Hearing (deafness)/Heart (myocarditis).
Q5 (examiner's probe): How is mumps prevented, and what are the contraindications to the vaccine?
Prevention is by the MMR (measles-mumps-rubella) vaccine — a live attenuated vaccine (Jeryl Lynn strain in most Western schedules). The schedule is two doses: first at 12 to 15 months, second at 4 to 6 years (at least 28 days apart). Efficacy is about 78 percent after one dose and 88 percent after two doses. Waning immunity over 10 to 20 years drives outbreaks in older vaccinated cohorts; in defined outbreak settings a third MMR dose reduces the attack rate (ACIP/CDC guidance). Post-exposure prophylaxis: MMR does not abort incubating infection (antibody response too slow) but should be given to susceptible contacts to protect future exposures; immune globulin is NOT effective for mumps post-exposure prophylaxis. Contraindications (because MMR is live): pregnancy (avoid conception for 1 month afterwards), severe immunocompromise (leukaemia, lymphoma, chemotherapy, high-dose steroids, advanced HIV, transplant), severe allergy to a component (gelatin, neomycin), and recent immunoglobulin (interferes with vaccine take). The MMR-autism link has been comprehensively refuted (Wakefield study retracted; Cochrane 2021 confirms no link).