Define Measles. Describe its clinical features, investigations, management and stages.

Definition

• Measles is a highly contagious viral illness caused by the measles virus (a paramyxovirus, RNA), spread by respiratory droplets.
• It remains an important cause of childhood morbidity and mortality (largely preventable by vaccination).

Clinical Features

• Prodrome — high fever with the '3 Cs': cough, coryza and conjunctivitis.
• Koplik spots — small white spots on the buccal mucosa — are pathognomonic and appear before the rash.
• Exanthem — an erythematous maculopapular rash with cephalocaudal spread (from behind the ears/hairline → face → trunk → limbs), which later fades with brownish staining and fine desquamation.

Complications (measles Is Dangerous Through its Complications)

• Otitis media (commonest) and pneumonia (commonest cause of death).
• Diarrhoea (with dehydration and worsening malnutrition), laryngotracheitis (croup).
• Neurological — febrile seizures, acute post-measles encephalitis, and the late, fatal subacute sclerosing panencephalitis (SSPE) years later.
• Vitamin A depletion → keratomalacia and blindness; reactivation of tuberculosis; severe malnutrition.

Investigations

• Usually a clinical diagnosis (prodrome, Koplik spots, typical rash).
• Measles-specific IgM serology confirms when needed (surveillance).

Management

• Supportive care — fluids, antipyretics, nutrition, and eye/mouth care.
• Vitamin A for all children with measles (reduces mortality and eye complications).
• Prompt treatment of complications — antibiotics for secondary bacterial pneumonia/otitis media.

Epidemiology & Infectivity

• One of the most contagious human infections; spread by respiratory droplets and aerosols.
• Infectious from ~4 days before to 4 days after rash onset; incubation ~10–14 days.

Stages of Illness

Incubation (~10–14 days) → Prodrome — fever + 3 Cs + Koplik spots (2–4 days) → Exanthem — cephalocaudal maculopapular rash → Recovery — staining and desquamation

Differential Diagnosis of a Maculopapular Rash

• Rubella (milder, posterior-auricular nodes), roseola, scarlet fever, drug rash.
• Koplik spots and the prodrome of 3 Cs help identify measles.

Modified & Atypical Measles

• Modified measles — milder illness in those with partial immunity (e.g. After immunoglobulin, young infants with maternal antibody).
• Immunocompromised children may have severe or atypical disease (e.g. Giant-cell pneumonia) without the classical rash.

Role of Nutrition

Measles and malnutrition form a vicious cycle — measles precipitates or worsens malnutrition and vitamin A deficiency, and malnourished children have far more severe measles; nutritional support and vitamin A are therefore integral to care.

Prevention

• Measles-containing vaccine (MR/MMR) — two doses (9–12 months and 16–24 months in the Indian schedule).
• Post-exposure prophylaxis — vaccine within 72 hours, or immunoglobulin for high-risk/immunocompromised contacts.
• Vaccination is the cornerstone of measles elimination.