The Measles virus is a member of the paramyxoviridae family of viruses. The virus infects the cells at the back of the throat and the cells lining the lungs. The disease it causes is called Measles or Rubeola (different from Rubella). According to the Centers for Disease Control and Prevention (CDC) in the United States, measles is the most deadly childhood disease and it is highly infectious.
Measles Communicability
The virus is spread by coughing and sneezing; proximity to an infected person will put one into contact with the virus. Transmission can occur up to 4 days before the appearance of the rash to 4 days after its appearance. If one person is infected, 90% of his susceptible (i.e. unimmunized) contacts will contract it. The virus can remain active on surfaces outside the body for 2 hours. It is estimated that the virus is so contagious that anyone who is not immunized will get the infection eventually.
Measles Infection
The physical manifestations last about a week and include rash, high fever, cough, runny nose, and red watery eyes. Common complications (approximately 20% of all infections) include diarrhea, middle ear infection (10% of cases), and pneumonia (5% of cases). In 1 of every 1000-2000 cases of infection, permanent brain damage is possible due to encephalitis. In children, the risk of severe complications and death is higher among those under the age of 5 years. Death occurs in roughly 1 per every 500 infections. Measles kills 1 million people worldwide each year and is the leading cause of blindness in African children.
Rubeola Prevention
Australia was recently declared to be measles-free, and the United States is considered to have no endemic strain since 2000 (only 150 cases occur each year). However, 84% of cases that do occur in the U.S. are brought back from travel to other countries and a lack of vaccination in recent years is making the United States susceptible to an outbreak. Each year, there are more than 20 million cases of measles worldwide.
The MMR (measles – mumps – rubella) or MMRV (MMR plus varicella) vaccine is administered to prevent measles, as it contains a weakened measles virus. There was some controversy in recent years about an association with autism, but the vaccine has not contained a mercury-based preservative (thimerosal) since 2001, and the Merck version of the vaccine (MMRII) has never contained the preservative. The original vaccine was licensed in 1971. Lifetime immunity occurs in 95% of those vaccinated. The booster is to cover the other 5%.
The first vaccine dose is given between 12 and 15 months age, and the booster can be given 4 weeks later or before the start of Kindergarten at 4-6 years of age. Some immunocompromised children may not be able to receive the vaccine; they should be protected from disease if approximately 90% of their peers are vaccinated (called herd immunity). Children who leave the U.S. for travel who are not old enough to receive the full vaccine can receive a monovalent vaccine.
Vaccine Side Effects
Less than a fourth of those who are vaccinated will be susceptible to side effects, which include a fever and rash 1-2 weeks after receiving the injection. One per 1,000,000 vaccinations will have an allergic reaction. The more common side effect is lymph swelling, a side effect of the immune response. Low platelet counts occur 1 per 100,000 vaccinations in the U.S. Neurological side effects are considered coincidental but should be treated to determine the cause.
For more information about other diseases protected against by MMR, read about Mumps.
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