The measles virus resides in the mucus in the nose and throat of the infected person. Measles transmission can occur when that person sneezes or coughs, and droplets spray into the air. The infected mucus can land in other people's noses or throats when they breathe or put their fingers in their mouth or nose after touching an infected surface. The virus remains active and contagious on infected surfaces for up to 2 hours. Measles transmission occurs so easily that anyone who is not immunized will probably get it eventually.
The majority of people infected with the measles virus recover, but measles complications are dangerous. Approximately 6 to 20 percent of the people who get the disease will develop a measles complication.
Measles causes ear infections in nearly 1 out of every 10 children who get it. As many as 1 out of 20 children with measles gets pneumonia, and about 1 child in every 1,000 who get measles will develop encephalitis. (This is an inflammation of the brain that can lead to convulsions, and can leave your child deaf or mentally retarded.) For every 1,000 children who are infected with the measles virus, 1 or 2 will die from it.
In pregnant women, measles infection can lead to miscarriage, premature delivery, or a low-birthweight baby.