Measles is a highly contagious respiratory disease (in the lungs) caused by a virus that is spread by direct contact with nasal or throat secretions of infected people. Measles is one of the most contagious viruses on earth; in fact, 90% of unvaccinated people exposed to the virus become infected. You can become infected by being in a room where a person with measles has been, up to 2 hours after that person is gone. And you can catch measles from an infected person even before they have a measles rash.
Symptoms usually appear 10-12 days after exposure but may appear as early as 7 days and as late as 21 days after exposure.
Measles typically begins with:
- high fever,
- runny nose (coryza)
- red, watery eyes (conjunctivitis)
Two or three days after symptoms begin, tiny white spots (Koplik spots) may appear inside the mouth.
Three to five days after symptoms begin, a rash breaks out. People are considered infectious from four days before to four days after the appearance of the rash.
LEARN MORE: Centers for Disease Control
If an Outbreak Occurs
If someone at a school develops measles, the local health department will initiate public health measures to contain the outbreak. The Health Department may exclude anyone (students and staff) from coming to the school who can not provide their personal immunity status. Those individuals may be excluded from school/work for up to 21 days after the onset of rash in the last reported case.