Measles

Measles is a highly contagious acute viral illness caused by the measles virus (a paramyxovirus). It spreads through the air via respiratory droplets when an infected person coughs or sneezes. Measles is one of the most infectious diseases known — one infected person can transmit the virus to 12–18 unvaccinated contacts. Before widespread vaccination, measles was a leading cause of childhood death in Nigeria. Despite the availability of a safe and effective vaccine, Nigeria continues to experience large measles outbreaks due to low and uneven vaccination coverage. Measles is not a mild childhood illness — it can cause pneumonia, encephalitis, blindness, and death, particularly in malnourished children and those with vitamin A deficiency.

Measles develops in stages after an incubation period of 10–14 days: Prodromal stage (3–5 days before rash): • High fever — often above 40°C (104°F) • Cough • Runny nose (coryza) • Red, watery, inflamed eyes (conjunctivitis) • Koplik's spots — tiny white spots with a bluish-white centre on a red background, appearing on the inner cheeks opposite the molars; pathognomonic (diagnostic) of measles, but present for only 1–2 days Rash stage: • Red, blotchy (maculopapular) rash that typically begins on the face and hairline • Spreads downward to the neck, trunk, arms, and legs over 3–4 days • Rash appears as fever is very high and begins to fade as fever subsides • The child may appear very unwell during this stage Recovery: • Fever typically subsides 2–3 days after the rash appears • Rash begins to fade after 5–6 days, sometimes leaving brownish discolouration A child with measles is infectious from 4 days before to 4 days after the rash appears.

Measles is caused by the measles virus (Morbillivirus), transmitted exclusively from person to person through: • Respiratory droplets released when an infected person coughs, sneezes, or talks • Airborne route — the virus can remain suspended in the air and on surfaces for up to 2 hours after an infected person has been in the room • Direct contact with nasal or throat secretions of an infected person There is no animal reservoir — measles only infects humans.

• Unvaccinated children — the primary risk group • Children under 5 years, especially under 1 year (before the first measles vaccination dose) • Malnourished children — severe malnutrition greatly increases the risk of fatal measles • Vitamin A deficiency — dramatically increases complications including blindness and death • Immunocompromised individuals (HIV, cancer treatment) • Communities with low vaccination coverage — measles spreads explosively when coverage falls below 95% • Internally displaced persons in camps • Areas where vaccination campaigns have been disrupted

Measles complications are frequent and can be severe — they occur in approximately 30% of reported cases: • Otitis media (ear infection) — the most common complication; can cause permanent hearing loss • Pneumonia — the most common cause of measles-related death; occurs in 1 in 20 cases • Encephalitis — brain inflammation occurring in approximately 1 in 1,000 cases; can cause permanent brain damage, deafness, intellectual disability • Corneal ulceration and blindness — particularly in vitamin A-deficient children; measles is a leading cause of childhood blindness in Nigeria • Severe diarrhoea and dehydration • Subacute sclerosing panencephalitis (SSPE) — a rare but fatal progressive brain disease that develops 7–10 years after measles infection • Death — estimated 1–5 per 1,000 cases in well-nourished populations; up to 1 in 4 in severely malnourished children

Vaccination — the most effective and only proven preventive measure: • Two doses of measles-containing vaccine (MCV) provide over 97% protection • In Nigeria: first dose at 9 months, second dose at 15–18 months (or as per the current national schedule) • Children who missed vaccination should receive catch-up doses as soon as possible • Ensure your child's vaccination card is up to date Vitamin A supplementation: • Vitamin A supplements are given to all children 6 months to 5 years every 6 months through routine immunisation contacts in Nigeria • During an active measles case: high-dose vitamin A given for 2 days significantly reduces severity and death Outbreak control: • Mass vaccination campaigns (supplementary immunisation activities, SIAs) rapidly build population immunity and contain outbreaks • Isolate infected children from school and other children for at least 4 days after the rash appears