Dear Doctors: I keep hearing about the complications that can happen when you have the measles and how they can land you in the hospital. I just saw on the news that getting the measles can mess up your immune system. I would like to know more about that.
Dear Reader: Measles is a highly contagious respiratory illness that is spread by an airborne virus. It typically causes an upper respiratory infection that ranges from mild to severe. Although the measles, mumps and rubella (MMR) vaccine is very effective at controlling the disease, dropping vaccination rates in areas of the United States are leading to outbreaks such as the one taking place in Texas and neighboring New Mexico. More than 200 cases have been confirmed so far, and two deaths have occurred. Local and state health departments tracking the outbreak warn that the actual numbers of cases are likely much higher than the official totals.
As we recently discussed in our column about measles vaccination guidelines, getting sick can lead to serious complications. These include ear infection; diarrhea; bronchitis, which is an inflammation of the bronchial tubes; and pneumonia, which is an accumulation of fluid in the lungs that starves the body of oxygen. Although rare, encephalitis, which is inflammation of the brain, is possible.
Your question involves a little-known complication of measles known as immune amnesia. This is a phenomenon in which portions of the immune system’s memory are wiped clean. It occurs because the measles virus can invade not only the cells of the respiratory system, but also the cells of the immune system. This includes the memory B cells, which are specialized white blood cells whose job is to recognize pathogens that the body has encountered and fought off before. When alerted by the memory B cells that they have come across a known pathogen, the immune system can swiftly mobilize the specific antibodies it needs to target and overcome the invader.
Without that early warning system in place, the immune system is perpetually flying blind. This leaves the person susceptible to contracting secondary infections from other pathogens, including those that they have successfully fought off before. Researchers have found that, after recovering from the measles, the immune system is suppressed for at least several months, and for up to two years.
One study looked at changes to immune system antibodies in blood samples collected from 77 unvaccinated children before a measles infection and again two months after infection. Analysis found that the measles virus had eliminated from 11% to 73% of the children’s store of antibodies. The same effect on the immune system was not seen in children who had received the MMR vaccine.
The CDC recommends children receive an initial dose of the MMR vaccine between the ages of 1 year and 15 months. A second dose should be given between the ages of 4 to 6. Unvaccinated teens and adults can get two doses of the vaccine at least one month apart. Doing so not only arms your child (and yourself) against measles, but it also protects your precious -- and hard-won -- immune memory bank.
(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)
