Measles
Measles is a highly contagious viral disease that spreads through the air and can cause fever, cough, rash, pneumonia, brain inflammation, and other serious complications.
What measles is
Measles, also called rubeola, is a viral disease caused by the measles virus. It is best known for fever and rash, but it is a whole-body infection that affects the respiratory tract, immune system, and other organs. Because it spreads so easily, even a small drop in community vaccination can allow outbreaks.
How it spreads
Measles spreads through the air when an infected person breathes, coughs, or sneezes. Virus particles can remain in the air or on surfaces for a period after the person leaves. People can spread measles before the rash appears, which makes it hard to rely only on visible symptoms to stop transmission.
Symptoms
Symptoms usually begin with high fever, cough, runny nose, and red watery eyes. Small white spots inside the mouth, called Koplik spots, may appear before the rash. The rash often starts on the face and then spreads downward across the body. Symptoms usually appear 7 to 14 days after exposure, but timing can vary.
Complications
Measles can be serious, especially for young children, pregnant people, and people with weakened immune systems. Complications can include ear infections, diarrhea, pneumonia, hospitalization, encephalitis, premature birth, low birth weight, and in rare cases subacute sclerosing panencephalitis, a delayed and usually fatal brain disorder.
Diagnosis and public-health response
Clinicians consider measles when someone has fever and rash along with compatible symptoms, especially after travel or exposure. Testing may include a throat or nasopharyngeal swab, urine specimen, and blood test. Because measles is so contagious, suspected cases trigger isolation, contact tracing, vaccination review, and communication with public-health authorities.
Vaccination
The MMR vaccine protects against measles, mumps, and rubella. In many schedules, children receive two doses, with the first in early childhood and the second before school age. Some infants, travelers, healthcare workers, or outbreak contacts may need specific timing advice. People with certain immune conditions or pregnancy should discuss vaccine safety with a clinician.
Herd protection
Measles control depends on very high vaccination coverage because the virus spreads so efficiently. Herd protection helps protect babies too young for routine vaccination and people who cannot safely receive live vaccines. When coverage becomes patchy, measles can find susceptible groups and move quickly through households, schools, clinics, and communities.
Why it matters
Measles matters because it is a warning light for public-health systems. A case can reveal gaps in vaccination, travel screening, outbreak response, health communication, and trust. Preventing measles protects individuals, but it also protects the people whose immune systems or age leave them dependent on the protection around them.