- Technical Answer
The measles virus is transmitted via respiratory secretions, and causes a very serious febrile illness. It first infects the respiratory mucosa, spreads through the lymphatics and bloodstream, and can then infect the conjunctiva, respiratory tract, urinary tract, GI tract, endothelial cells, and the central nervous system. The maculopapular rash, which starts at the hairline and spreads over the whole body, is caused by immune T-cells targeted to the infected endothelial cells of the small blood vessels. T-cell deficient individuals do not have the rash, but do have uncontrolled disease which usually results in death. The damage, as well as the control of the disease, is most probably caused by the immune system. Pneumonia and encephalitis are serious consequences. Subacute sclerosing panencephalitis (SSPE) is a very serious sequelae caused by a defective measles virus. It can cause neurological symptoms months or even years after the original infection. A live, attenuated vaccine has been available since 1967. It is given in combination with mumps and rubella vaccines (MMR) after 15 months of age. Individuals who received the killed vaccine prior to the introduction of the live attenuated vaccine do not have lasting immunity and should be revaccinated with the live virus. It is now also recommended that all individuals be re-vaccinated after eighteen years of age. Exposed, non-immune, individuals should be given immune serum globulin.
- Measles Basics
Measles is primarily a respiratory infection caused by a highly contagious virus found all over the world. The symptoms include fever, runny nose, cough, sore and reddened eyes, followed by the characteristic red-brown rash. The rash usually starts on the face and spreads down the body, lasting three or more days.
The incubation period - that's the time between exposure to someone with the disease and the onset of the symptoms - is about 10 days. The red rash shows up three days to a week after the first symptoms. People are contagious from just before symptoms appear until 4 to 5 days after the rash appears.