Open Outbreak

Measles

Also known as: rubeola, morbillivirus, morbilli, red measles

Measles is a highly contagious viral disease that spreads mainly through the air and respiratory droplets from an infected person. WHO describes it as an airborne viral disease, and one WHO outbreak notice says about 90% of non-immune people exposed to an infectious person are estimated to become infected. Symptoms usually begin about 10 to 14 days after infection and often start with high fever, cough, runny nose, and red eyes, followed by a widespread rash. Measles can be severe, especially in children under 5 years, malnourished children, people with vitamin A deficiency, and people with weakened immune systems. Outbreak reports in recent years have included deaths in several countries. There is no specific antiviral cure described in the WHO outbreak notices used here. Prevention depends on vaccination, and WHO repeatedly notes that two doses of measles-containing vaccine can prevent the disease. Supportive care and vitamin A are important parts of case management, especially for children at risk of complications.

Key facts

TransmissionAirborne and via droplets from the nose, mouth, or throat of an infected person; WHO also notes that about 90% of non-immune exposed people may become infected.
IncubationUsually 10 to 14 days after infection, according to WHO outbreak notices.
Case fatalityVaries by setting. Examples from WHO outbreak notices include 0.14% in Nepal in 2023, 1.06% in South Sudan in 2023, 1.1% in Ethiopia in 2023, and 0.9% in Bangladesh in 2026.
Reproduction numberunknown
VaccineA safe and effective measles-containing vaccine is available; WHO states that two doses can prevent measles.
TreatmentNo specific antiviral cure identified in the sources used here; care is mainly supportive, and WHO highlights case management and vitamin A in outbreak response.
ReservoirHumans
Endemic regionsStill endemic in parts of Africa and Asia; WHO outbreak notices also describe repeated importation-related outbreaks in other regions.

Transmission

Measles spreads very easily from person to person. WHO describes it as an airborne viral disease and also says it can spread through droplets from the nose, mouth, or throat of an infected person. In practice, that means a sick person can infect others by breathing, coughing, or sneezing, especially indoors. One WHO measles notice states that about 90% of non-immune people exposed to an infectious person are estimated to become infected. WHO outbreak notices also say initial symptoms usually appear 10 to 14 days after infection. Because it spreads so efficiently, even a single imported case can start an outbreak if many people in the community are unvaccinated or have unknown vaccine status. The reservoir is human beings rather than animals, so spread depends on chains of infection between people and can be interrupted when vaccination coverage is high.

Symptoms and severity

Measles often starts like a bad feverish cold. WHO says the first symptoms usually include high fever, runny nose, bloodshot or red eyes, and cough. A rash follows later. The encyclopedia summary used here also mentions Koplik spots, small white spots inside the mouth, before the rash appears. Illness can be much more than a rash. Reported complications include diarrhoea, ear infection, pneumonia, seizures, blindness, and inflammation of the brain. WHO stresses that severe disease is more likely in children under 5 years, malnourished children, people with vitamin A deficiency, and people with weakened immune systems. Recent outbreak notices show that deaths still occur, especially where vaccination coverage is low or health systems are under strain. Reported case fatality ratios have varied by country and year, from 0.14% in Nepal in 2023 to around 1.1% in Ethiopia in 2023 and 0.9% in Bangladesh in 2026.

Treatment and vaccines

The main protection against measles is vaccination. WHO states in its recent outbreak notices that measles is preventable with two doses of measles-containing vaccine, and it repeatedly describes the vaccine as safe and effective. Outbreak responses in Bangladesh, Morocco, South Africa, South Sudan, and other countries have included catch-up or reactive vaccination campaigns, often aimed at children who missed routine doses. The sources used here do not describe a specific antiviral cure. Instead, they refer to case management and supportive care, which means treating dehydration, fever, breathing problems, and other complications. WHO also highlights vitamin A deficiency as a risk factor for severe disease, and vitamin A is commonly included in measles management in high-risk children. The practical message is simple: treatment can reduce harm, but prevention through timely vaccination is far more effective than trying to control spread once outbreaks begin.

Where it occurs

Measles can appear anywhere that the virus is introduced into a group of susceptible people. WHO notes that it is still common in many developing countries, particularly in parts of Africa and Asia, and some outbreak notices call it endemic in countries such as Ethiopia and Indonesia. But it is not limited to those places. Recent WHO notices also describe outbreaks or importation-linked cases in the United States, Morocco, Chile, and across the Region of the Americas. This pattern matters because it shows two different situations: some countries have ongoing local transmission, while others mainly face imported cases that spread when vaccine coverage has gaps. In the Americas, WHO said in 2025 that most confirmed cases were imported or linked to importation. So measles is both an endemic disease in some regions and a recurring reintroduction risk in places that had previously interrupted endemic transmission.

Recent history

This site’s archive lists 31 measles-related WHO notices or major events since 1996, showing that measles returns to the outbreak record again and again. The recent pattern is a broad resurgence rather than one isolated event. WHO posted notices for South Sudan, Nepal, South Africa, Indonesia, and Ethiopia in 2023. In 2025 it reported outbreaks or sharp increases in the United States, Morocco, and the Region of the Americas. In 2026, Bangladesh notified WHO of a nationwide increase affecting 58 of 64 districts, with 19,161 suspected cases, 2,897 laboratory-confirmed cases, and 166 measles-related deaths reported between 2026-03-15 and 2026-04-14. WHO’s assessments repeatedly link these events to immunity gaps, missed vaccination, weak surveillance in some areas, displacement, or importation into under-vaccinated communities. Taken together, the archive supports the idea that measles is resurging where routine vaccination and follow-up campaigns do not keep population immunity high.

What to watch

The main warning signs are not mysterious. First, watch for spread into new districts, provinces, or countries after an imported case, especially where many children or young adults are unvaccinated. Second, watch for evidence of sustained community transmission rather than a single travel-linked cluster. Third, watch for rising deaths or severe complications in children under 5 years, malnourished children, and people with weak immune systems. Fourth, watch for surveillance gaps, because WHO has warned that under-detection and weak notification can hide the true scale of spread. Fifth, watch whether routine vaccination and catch-up campaigns are reaching enough people; repeated WHO notices link outbreaks to low coverage or missed second doses. Vaccine supply interruptions or delayed campaigns would make the outlook worse. The sources used here do not identify antiviral resistance as a present concern, so the bigger practical risks are widening immunity gaps, cross-border spread, and delayed outbreak response.

Related outbreaks

Updated