I may have been exposed to measles. What do I need to know?
In the late 1950’s and early 1960’s, back when the U.S. population was 180 million, there were 3 to 4 million cases of measles each year in America, along with 48,000 hospitalizations and about 500 deaths from measles. A measles vaccine combined with mumps and rubella vaccines – the MMR – was introduced in 1963, and it quickly became a standard part of children’s health care. By 2000, there were only 86 isolated cases in the entire nation, and there had been no continuous transmission of the infection for more than 12 months. The disease was declared eliminated in our country, and it is highly unlikely your doctor has ever seen a case of measles. However, measles has been in the news frequently in 2019 because it is making a comeback in the U.S. Measles is one of the world’s most contagious diseases. It is spread by coughing and sneezing, or direct contact with infected nasal or throat secretions. The virus remains contagious in the air for up to 2 hours and longer on surfaces. That means the virus can still infect others 2 hours after a contagious person has left the room. An infected person sheds the virus and is contagious for 8 to 10 days, starting a few days before feeling sick. Following an exposure, 90% of susceptible people will develop measles. Symptoms usually start 10 to 12 days after exposure but can be anywhere from 6 to 21 days. These symptoms include a fever, loss of appetite and just not feeling well, followed by dry cough, runny nose, and red or watery eyes. White spots sometimes appear on the insides of the cheeks. The illness might be mistaken for the common cold if not for its most well-known symptom – a rash that usually starts on the face and head and spreads downwards. It typically appears 2 to 4 days after the fever begins and 14 days after exposure. The virus causes far more than discomfort. Complications range from mild ones, such as diarrhea, to more serious ones, such as ear infections, pneumonia, blindness, and encephalitis (swelling of the brain that can cause permanent brain damages). A significant number of people who get measles die from it – about 150,000 around the world, according to the World Health Organization. However, once infected, there is little to be done except to let the virus run its course and to take precautions to help prevent the spread of the disease. Most people born in the United States after 1970 received the MMR vaccine and are immune to the virus, however, segments of the populations who are not vaccinated are at risk of infection. People born before 1957 were likely exposed to measles and have developed their own natural immunity. Anyone who has had measles is also immune. Measles is still common in other parts of the world, and it is thought that many of the recent outbreaks in the U.S. were caused by travelers who picked up the virus abroad and infect non-immunized individuals here. It is more likely to spread and cause outbreaks in U.S. communities where groups of people are unvaccinated. This is because of community immunity, also called herd immunity. If a certain proportion of the population is protected, the germ – in this case, the measles virus – doesn’t find enough susceptible people to take hold in the community. So even if there is an isolated case, no epidemic occurs. This means that the fraction of the population that has immunity is protecting everyone, including those who are too young to be vaccinated and those who cannot be immunized due to being immunocompromised. But to achieve community immunity for measles at least 90 to 95% of the population must be immune. A disease like polio is less contagious, and only 80 to 85 percent of the population would need to be vaccinated for herd immunity to work. If you are unsure whether or not you are immune, you can be tested for immunity to the disease by your primary physician or an urgent care center such as Yubadocs. It is especially important to know your status if you plan to travel internationally or have been exposed to others who may be carrying the disease. Unlike influenza vaccine, which reduces the risk of influenza illness between 40 to 60%, two doses of the measles vaccine is 99% effective. Measles vaccine does not wane with age, and it is never too old to get vaccinated.