What is measles, and why is it still dangerous?
Measles is a highly contagious acute viral infection caused by the measles virus (Morbillivirus, family Paramyxoviridae). A notifiable disease in France, it killed 100,000 children worldwide in 2023 (WHO) despite the availability of an effective vaccine since 1963. The basic reproduction number (R₀ = 12–18) is one of the highest among all infectious diseases—a single infected person can spread the disease to 12 to 18 unvaccinated individuals. Any suspected febrile rash in an unvaccinated child requires urgent medical attention. Explore our Immunity line and our Respiratory Health line for natural support during recovery.
- Transmission: airborne transmission via aerosols and droplets—one of the most efficient modes of transmission known (the virus survives for 2 hours in the air of a closed room after the infected person has left) — contact with contaminated surfaces + touching the face with hands — peak contagiousness 4 days before the rash appears until 4 days afterward — contagious individuals often do not yet know they are infected
- Clinical phases: incubation period 10–14 days (asymptomatic) — prodromal phase 3–5 days — high fever (40–41 °C) + cough + runny nose + conjunctivitis (“3Cs”) — Koplik spots (small white spots on a red background inside the cheeks, opposite the molars—pathognomonic of measles)—rash phase: days 14–17 — descending maculopapular rash (face → trunk → limbs) — persistent fever ≥ 39 °C during the rash
- Koplik spots: pathognomonic sign — appear 1–2 days before the skin rash — allow for early diagnosis — disappear 1–2 days after the rash begins
- Diagnosis: clinical (typical presentation + epidemic context) — laboratory confirmation: measles-specific IgM (serology) or nasopharyngeal or urinary RT-PCR — mandatory reporting to the Regional Health Agency (ARS) within 24 hours of suspected diagnosis
- Populations at increased risk of complications: infants < 1 year old (not yet vaccinated) — malnourished children (vitamin A deficiency) — unvaccinated adults (more severe forms) — pregnant women — immunocompromised individuals
Complications and warning signs
- Measles pneumonia: the most common complication and leading cause of death (1 in 20 cases in developing countries)—viral pneumonia (measles virus) or secondary bacterial pneumonia (Staphylococcus aureus, pneumococcus) — persistent fever + worsening cough + shortness of breath → seek urgent medical attention
- Acute post-measles encephalitis: 1 in 1,000 cases — appears 1–2 weeks after the rash — headache + fever + seizures + altered consciousness — 15% mortality rate + neurological sequelae in 25% of survivors
- Subacute sclerosing panencephalitis (SSPE): a rare but always fatal complication (1–4 per 100,000 cases) — occurs 5–10 years after infection (especially if measles occurred before age 2) — progressive brain degeneration — no effective treatment — prevention = vaccination before 12 months
- Acute otitis media: the most common complication in children (1 in 10 cases) — fever and earache following the rash — risk of hearing loss if recurrent or poorly treated
- Keratoconjunctivitis and blindness: a serious complication, especially in cases of vitamin A deficiency (common in developing countries) — vitamin A supplementation recommended by the WHO for all children with measles in high-risk areas
MMR Vaccination, Guidelines, and Exposure Management
- MMR (measles-mumps-rubella) vaccine: live attenuated vaccine — >97% effective against measles after 2 doses — French vaccination schedule: 1st dose at 12 months, 2nd dose at 16–18 months — mandatory vaccination in France since 2018 for children born after January 1, 2018 — Booster recommended for adults born between 1980 and 1989 who received fewer than 2 doses and for healthcare professionals — lifelong immunity after 2 doses
- Herd immunity threshold: 95% vaccination coverage required (due to high R₀) — a decline in vaccination coverage = risk of an outbreak — recent outbreaks in France (2018–2019) linked to areas with low vaccination coverage
- What to do in case of exposure: contact your doctor as soon as you suspect exposure—post-exposure vaccination is possible if administered within 72 hours (effectiveness > 90% if the vaccination series is incomplete) — Immunoglobulins (polyvivalent Ig) within 6 days for at-risk individuals (infants < 6 months, immunocompromised individuals, unvaccinated pregnant women) — Strict isolation of the case until Day 4 after rash onset
- Pregnant women: severe measles in the mother (pneumonia, hepatitis) + risk of miscarriage, preterm birth, and fetal death — MMR vaccine contraindicated during pregnancy (live vaccine) → check immunity before any pregnancy + vaccination if necessary before conception — if exposed during pregnancy → emergency administration of immunoglobulins
- Isolation: Stay at home from Day 4 before the rash appears until Day 4 after the rash appears — mandatory exclusion from school — report to the Regional Health Agency (ARS) for an epidemiological investigation of the case
Symptomatic care and natural support during recovery
- Symptomatic treatment: no specific antiviral treatment — acetaminophen 15 mg/kg per dose for children or 500–1,000 mg for adults for fever and pain — never use aspirin in children with a viral infection (risk of Reye’s syndrome) — humidifier (relieves cough and soothes irritated mucous membranes) — saline eye drops for conjunctivitis
- Hydration is essential: high fever and mucosal secretions increase fluid requirements — 2–3 L/day for adults — light, bland foods if the mouth is affected — avoid acidic foods if Koplik spots are painful
- Vitamin A: recommended by the WHO for all children with measles in areas with a high prevalence of deficiency (Africa, Asia)—reduces mortality and ocular complications by 50%—2 doses: 200,000 IU on Day 1 and Day 2 (50,000 IU if < 6 months, 100,000 IU if 6–12 months) — discuss with a doctor in France if malnutrition or a documented deficiency is present
- Immune support during recovery: Measles causes prolonged immunosuppression (2–3 years — “immune amnesia”) — vitamin C + vitamin D3 + zinc during recovery — see our page on immune defenses — compare with mumps and chickenpox as part of the MMR vaccination schedule
- Warning signs requiring urgent medical attention: fever > 39 °C persisting for > 5 days — worsening cough + shortness of breath (pneumonia) — severe headache + seizures + altered consciousness (encephalitis → call 15) — ear pain (otitis) — eye involvement (keratitis) — any infant < 6 months with a febrile rash
