In older children, measles can cause an infection of the brain called encephalitis, which results in permanent brain damage in about 25 percent of those who get it. About seven years after having had measles, a child with SSPE will develop personality changes, weakness, seizures, and brain damage, eventually going into a coma and dying. Before the vaccine was introduced in 1963, the United States had between 3 and 4 million cases of measles each year, with more than 300 deaths from the disease. These days the United States has about a hundred annual cases with no deaths. When measles vaccination rates went down in 1990, there was an outbreak of 28,000 cases of measles, and 30 children died.
Mumps is a viral infection that typically causes a mild fever and a swollen jaw.
Before the mumps vaccine was introduced in 1967, the Unites States had about 200,000 cases of mumps every year, with 20 to 30 deaths. Mumps was also the most common cause of acquired deafness and of viral meningitis, an infection of the lining of the brain. Up to 40 percent of males who are infected with mumps after puberty develop a painful swelling of the testicles called orchitis, which in rare cases can lead to sterility and testicular cancer. Today the United States has about 350 cases of mumps each year. It's a mild illness that runs its course in about three days, but if a woman gets it during the first trimester of pregnancy, her child has an 85 percent chance of blindness, deafness, heart defects, or mental retardation.