What is measles?

SHORT ANSWER:

Measles is a respiratory disease caused by a virus that grows in the cells that line the back of the throat and lungs. The disease is very contagious, and is most commonly spread through coughing and sneezing. People can also catch the measles by touching a surface that has been coughed or sneezed on by an infected person, then touching their own mouth or nose. Measles causes fever, runny nose, cough, and a rash all over the body. About 30% of measles cases will develop additional complications. Ninety-five percent of those who receive the Measles-Mumps-Rubella (MMR) or monovalent measles vaccine at age 1 or older are immune after the first dose. After the second dose, 99.7% of those immunized are protected. Immunity is lifelong.

Source:

http://www.cdc.gov/measles/about/overview.html

http://www.immunizationinfo.org/vaccines/measles

Symptoms & Incubation
The symptoms of measles generally begin about seven to 14 days after a person is infected, and include blotchy rash, fever, cough, runny nose, red and watery eyes (conjunctivitis), feeling run down and achy (malaise), and tiny white spots with bluish-white centers found inside the mouth (Koplik’s spots). A typical case of measles begins with mild to moderate fever, cough, runny nose, red eyes, and sore throat. Two or three days after symptoms begin, tiny white spots (Koplik’s spots) may appear inside the mouth.

Three to five days after the start of symptoms, a red or reddish-brown rash appears. The rash usually begins on a person’s face at the hairline and spreads downward to the neck, trunk, arms, legs, and feet. When the rash appears, a person’s fever may spike to more than 104 degrees Fahrenheit. After a few days, the fever subsides and the rash fades.

Complications

Complications can include:

  • Pneumonia, which is the complication that is most often the cause of death in young children.
  • Ear infections occur in about one in 10 measles cases and permanent loss of hearing can result.
  • Diarrhea is reported in about 8% of cases.

These complications are more common among children under 5  years of age and adults over 20 years old.

Even in healthy children, measles can be a serious illness requiring hospitalization. As many as one out of every 20 children with measles gets pneumonia, and about one 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 the child deaf or mentally retarded.) For every 1,000 children who get measles, one or two will die from it. Measles also can make a pregnant woman have a miscarriage, give birth prematurely, or have a low-birth-weight baby. While measles is almost gone from the United States, it still kills nearly 200,000 people each year around the world.

Subacute sclerosing panencephalitis (SSPE) is a rare fatal illness caused by ongoing measles virus infection of the brain. Symptoms of brain damage usually begin 7 to 10 years after infection. Death occurs one to three years after the onset of symptoms. Risk factors for developing SSPE include developing measles infection at a young age. The incidence of SSPE is estimated to be between 7-11 cases/100,000 cases of measles. Measles vaccine virus was not associated with SSPE.

Transmission

Measles is highly contagious and can be spread to others from four days before to four days after the rash appears. Measles is so contagious that if one person has it, 90% of the people close to that person who are not immune will also become infected with the measles virus. The virus lives in the mucus in the nose and throat of the infected person. When that person sneezes or coughs, droplets spray into the air. The droplets can get into 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 can live on infected surfaces for up to two hours. Measles is a disease of humans; measles virus is not spread by any other animal species.

High-risk populations

Death from measles is more common in infants, in malnourished children, and among people with compromised immune systems, including those with leukemia and HIV infection.

Vaccine

The measles vaccine is available by itself (monovalent measles vaccine) or as part of two combination vaccines: measles-mumps-rubella (MMR) and measles-mumps-rubella-varicella (MMRV). Ninety-five percent of those who receive the vaccine at age 1 or older are immune after the first dose. After the second dose, 99.7% of those immunized are protected. Immunity is lifelong.

Safety & Side Effects
The MMR vaccine is very safe, and it is effective at preventing measles (as well as mumps and rubella). Vaccines, like any medicine, can have side effects. Most children who get the MMR vaccine have no side effects. Those that do occur are typically very minor and may include the following:

  • Fever in one out of six people
  • Mild rash in one out of 20 people
  • Swollen glands in the cheeks or neck in very few people
  • Fever high enough to cause a seizure (jerking or staring) occurs in one out of 3,000 people. These seizures do not cause any long-term harm.
  • Temporary joint pain and stiffness (mostly in teens and adults)

Serious allergic reaction to the MMR vaccine occurs in fewer than one in a million people.

The vaccine does not cause autism. There are a couple of reasons why people believe autism is linked to vaccination. The first is because sometimes signs of autism don’t appear until around the age the MMR vaccine is given. If a child is diagnosed shortly after getting vaccinations, this may seem like cause and effect.

Another reason some people think MMR is linked to autism is because of a study published in 1998 in the United Kingdom journal The Lancet. One of the authors claimed that the MMR vaccine could contribute to the development of autism. The publishers later retracted the article when they discovered it was false, and 10 out of 13 of the study’s authors have withdrawn their support of the study. Since then, 12 large-scale studies have produced no evidence that children who receive the MMR vaccine are at greater risk of autism than those who don’t.

Schedule

Two doses of MMR vaccine administered on or after the first birthday are recommended for all children, including those who previously received the monovalent measles vaccine. The first dose is generally given at 12 to 15 months of age, and the second dose is generally given at 4 to 6 years of age. There must be a minimum of four weeks between doses.

Since the Vaccine Was Introduced…

Before the first measles vaccine was licensed in 1963, virtually every person in the U.S. got the measles by age 20. Since the vaccine became available, there has been a 99% reduction in the incidence of measles. However, measles is still being imported from other countries.

Because of widespread misinformation about MMR in the United Kingdom, MMR vaccine coverage has declined across Europe, resulting in outbreaks of measles and mumps in multiple countries, including the United States and Canada, and congenital rubella in the Netherlands and Canada. There were 140 cases of measles in the United States in 2008; more than three quarters of these cases were linked to imported measles from another country; most of the cases were unimmunized American children.