Measles — SAQ

Stem

A 4-year-old unvaccinated girl is brought to the OPD with 5 days of high fever (39.5 degrees C), harsh dry cough, sneezing, and red watery eyes with photophobia. Today her mother noticed a red blotchy rash starting behind the ears and at the hairline, now spreading to the face and neck. On examination, the buccal mucosa opposite the lower second molars shows tiny 1-3 mm blue-white papules on a bright-red erythematous base. There is bilateral conjunctivitis and coryza. Respiratory rate is 42/min, SpO2 95 percent on room air. The child is irritable but alert.

She has no prior MMR vaccination. She attends a playschool where two other children have had similar illness. Her mother is 14 weeks pregnant and has never had measles or been vaccinated.

Questions

a) What is the diagnosis, and what is the pathognomonic sign? (2 marks)

Measles (rubeola) due to the measles morbillivirus (Paramyxoviridae). The pathognomonic sign is Koplik spots — small (1-3 mm) bluish-white 'grains of salt' papules on a bright-red erythematous buccal mucosa opposite the lower second molars, appearing in the late prodrome (1-2 days before the rash). The full picture of fever + the 3 Cs (cough, coryza, conjunctivitis) + Koplik spots + a cephalocaudal maculopapular rash is diagnostic. The playschool cluster with the same illness supports the diagnosis (R0 12-18; highly contagious).

b) Outline your immediate (resuscitative) actions. (3 marks)

1. Isolate immediately with AIRBORNE precautions — single room, preferably negative-pressure, FFP3/N95 for staff (measles aerosolises and remains infectious in air for up to 2 hours). Isolate for at least 4 days after the rash appeared (longer if immunocompromised).
2. Notify public health immediately — measles is statutorily notifiable; it triggers contact tracing and outbreak control.
3. Confirm the diagnosis — send measles IgM serology (positive 1-2 days after rash) and RT-PCR on throat swab/urine (most sensitive in first 3-4 days of rash; allows genotyping).
4. ABCDE and supportive: monitor RR, SpO2; the RR of 42 and SpO2 95 percent suggest early lower-respiratory involvement — start oxygen if SpO2 drops, IV access, fluids if dehydrated.
5. Give vitamin A on the day of diagnosis — 200,000 IU orally now, repeat in 24 h (she is over 12 months).
6. Treat complications early — re-examine for pneumonia, otitis, dehydration, encephalitis, keratitis.

c) Outline the definitive management. (3 marks)

• No specific antiviral of proven benefit. Management is supportive:
  • Antipyretics: paracetamol 10-15 mg/kg every 4-6 h (max 60 mg/kg/day); AVOID aspirin in children (Reye syndrome).
  • Hydration, nutrition; continue breastfeeding; oral intake maintained; IV fluids if dehydrated.
  • Eye care for keratitis/conjunctivitis; ophthalmology review if photophobia/corneal signs.
• Vitamin A: two doses 24 h apart — 200,000 IU orally (age >=12 months); reduces mortality ~50-60 percent and prevents blindness (Hussey & Klein 1990 NEJM; WHO 2017).
• Treat secondary bacterial infection — otitis media (oral amoxicillin 40-90 mg/kg/day in 2-3 divided doses for 5-10 days); pneumonia (ceftriaxone plus azithromycin if severe).
• Infection control: airborne precautions for 4 days after rash; HCW documented immunity only.
• Public-health action: identify contacts; offer MMR within 72 h or HNIG within 6 days to susceptible contacts.

d) Detail the post-exposure prophylaxis for her mother (14 weeks pregnant). (1 mark)

The mother is susceptible (no prior measles, never vaccinated) and pregnant — therefore live MMR is CONTRAINDICATED. She should receive human normal immunoglobulin (HNIG) IM within 6 days of exposure — dose 0.5 mL/kg IM, maximum 15 mL. This gives passive protection and may attenuate disease. Measles is NOT teratogenic (unlike rubella) but raises the risk of miscarriage, premature labour, and severe maternal pneumonia. Counsel accordingly, and administer MMR postpartum (two doses, separated by at least 4 weeks, with a 1-month contraception interval before a future pregnancy).

e) Name two serious neurological complications of measles and briefly describe each. (1 mark)

1. Acute measles encephalitis / post-infectious encephalomyelitis (ADEM) — demyelinating autoimmune process occurring within 2-14 days of the rash; ~1 in 1000 cases; mortality 15 percent, permanent sequelae in 25-40 percent.
2. Subacute sclerosing panencephalitis (SSPE) — a persistent defective (M-protein-mutant) measles virus infection of neurons appearing 5-15 years after natural measles (earlier and more frequent when measles was acquired under 2 years); progressive cognitive/behavioural decline, myoclonus, seizures, EEG periodic complexes with burst-suppression, raised measles antibody in CSF/serum; uniformly fatal in 1-3 years.

(Also accept: measles inclusion-body encephalitis, MIBE — within 1-10 months, in the immunocompromised, often fatal.)

References4ShowHide

1. [1]Rota PA, Moss WJ, Takeda M, et al. Measles. Nature Reviews Disease Primers, 2016.PMID 27411684
2. [2]Moss WJ, Griffin DE. Measles. Lancet, 2012.PMID 21855993
3. [6]Hussey GD, Klein M. A randomized, controlled trial of vitamin A in children with severe measles. N Engl J Med, 1990.PMID 2194128
4. [7]World Health Organization. Measles vaccines: WHO position paper - Recommendations. Vaccine, 2019.PMID 28760612