Mumps — SAQ

Stem

An 18-year-old male college student presents to the outpatient department with a 3-day history of fever (38.8 degrees C), malaise, headache and progressive painful swelling at the angle of the jaw. He has had difficulty chewing and drinking orange juice because of the pain. He received only one dose of the MMR vaccine in childhood (his parents stopped the immunisation schedule after a relative reported a "vaccine reaction"). He lives in a college dormitory where two other students have had similar illness in the past month.

On examination: temperature 38.9 degrees C, pulse 96/min, BP 118/74 mmHg. There is bilateral, tender, smooth parotid swelling that lifts both ear lobes upwards and forwards and obscures the angle of the mandible; the overlying skin is normal. The submandibular glands are also slightly enlarged and tender. The Stensen duct orifices are red and oedematous but express no pus on gentle milking. There is no cervical lymphadenopathy, no oropharyngeal exudate, and no rash. The abdomen is soft.

Questions

a) What is the clinical diagnosis, and which pathogen causes it? Classify the virus. (2 marks)

Mumps (epidemic parotitis). The pathogen is the mumps virus — an enveloped, non-segmented, negative-sense single-stranded RNA virus of the Paramyxoviridae family, Rubulavirus genus. Its two surface glycoproteins are HN (haemagglutinin-neuraminidase), which binds sialic-acid receptors on host epithelium, and F (fusion), which mediates viral entry and cell-to-cell fusion, producing the cytopathic hallmark of paramyxoviruses — multinucleated giant cells (syncytia). The diagnosis here is clinical: bilateral tender parotid swelling lifting the ear lobes and obscuring the jaw angle, fever, known dormitory outbreak, and a single (incomplete) MMR dose.

b) List four characteristic clinical features and the key bedside sign distinguishing parotid from cervical lymph node swelling. (2 marks)

Characteristic features:

• Fever, malaise, headache with a 1-2 day prodrome.
• Bilateral, tender, smooth parotid swelling lifting the ear lobe and obscuring the jaw angle (bilateral in 70 percent, sequential).
• Submandibular and sublingual gland involvement (10 percent); pain on chewing or drinking acidic juices.
• Stensen duct orifice red and oedematous but NO pus on milking (distinguishes from bacterial parotitis).

The key bedside distinction: true parotid swelling LIFTS the EAR LOBE UPWARDS AND FORWARDS and OBLITERATES the ANGLE of the MANDIBLE, whereas cervical lymphadenopathy lies BELOW and BEHIND the angle of the jaw and does NOT move the ear lobe.

c) Outline the definitive management, the public-health action required, and the FOUR specific drugs/interventions that are NOT indicated. (3 marks)

Management is supportive (there is no specific antiviral of proven benefit):

• Rest, adequate hydration (oral or IV if dehydrated), soft non-acidic diet (avoid citrus/acidic juices which aggravate parotid pain).
• Analgesia/antipyretics: paracetamol 1 g PO every 6 hours (max 4 g/day; 15 mg/kg/dose in children) and/or ibuprofen 400 mg PO every 8 hours (5 to 10 mg/kg/dose in children over 3 months).
• Local measures: warm or cold compresses over the parotid, salt-water gargles, good oral hygiene.

Public-health action:

• Isolate with droplet precautions and exclude from college/work for 5 days AFTER the onset of parotid swelling (peak infectivity is 2 days before to 5 days after parotitis).
• Notify public health (mumps is notifiable).
• Trace and vaccinate susceptible contacts (single-dose contacts should receive their second MMR dose).

Drugs/interventions NOT indicated:

1. Antivirals (ribavirin, interferon, aciclovir) — no proven benefit.
2. Antibiotics — add nothing to viral mumps (reserve for bacterial parotitis).
3. Routine corticosteroids — not indicated for uncomplicated parotitis; reserve for severe orchitis or sensorineural deafness; do NOT prevent infertility.
4. MMR as post-exposure prophylaxis for HIM — too slow to abort incubating infection (but should be given to susceptible contacts to protect future exposures).

d) The patient returns 6 days later with acute, severe right testicular pain and swelling, high fever and vomiting. What is the complication, what MUST be excluded immediately, and outline the management of the complication once that is excluded. (2 marks)

Complication: mumps orchitis (occurs in 20 to 30 percent of post-pubertal males, usually unilateral, typically 4 to 10 days after parotitis).

MUST EXCLUDE IMMEDIATELY: testicular TORSION — a surgical emergency. Send for urgent Doppler ultrasound and urology review; if torsion cannot be excluded, explore surgically. (Torsion: sudden onset, high-riding transverse testis, absent cremasteric reflex, severe pain; mumps orchitis: gradual onset in the context of mumps, hypervascular flow on Doppler.)

Management of mumps orchitis (once torsion excluded):

• Bed rest, firm scrotal support/elevation (rolled towel), ice packs, NSAIDs/paracetamol.
• Severe refractory pain: spermatic-cord nerve block; short-course corticosteroid (prednisolone 40 to 60 mg/day for 1 to 2 weeks, tapered) — reduces pain and inflammation but does NOT prevent testicular atrophy or infertility.
• Counsel the patient that infertility is rare even when bilateral; testicular atrophy may occur in up to 50 percent of affected testes over months.

e) Name three other recognised complications of mumps (besides orchitis), and state which is usually permanent. (1 mark)

• Aseptic meningitis / meningoencephalitis (CSF pleocytosis in 50 to 60 percent; symptomatic meningitis in 1 to 10 percent; rare severe encephalitis ~0.1 percent).
• Pancreatitis (2 to 5 percent; epigastric pain radiating to the back, raised lipase).
• Sensorineural deafness (about 1 in 20,000; usually unilateral, sudden, and often PERMANENT — a leading acquired cause of unilateral childhood deafness where mumps is endemic).
• Also accept: oophoritis, myocarditis, arthritis, thyroiditis, first-trimester miscarriage.

Sensorineural deafness is the complication that is typically permanent.