Sunday, June 29, 2014

Measles outbreaks in Washington State

Andrew received a dose of measles, mumps, rubella, and varicella (MMRV) vaccine at 12 months of age.

This past week we saw the first case of measles in a Pierce County resident since 2006.

Our newest case is a 13-month-old child that was seen in an emergency department (ED) in Tacoma on June 10th for an unrelated condition. Unfortunately, there was a King County resident in the ED who had contracted measles from an unvaccinated person who had returned to the U.S. on May 26th. While he was contagious, the 13-month-old Pierce County resident was seen in the Mary Bridge/Tacoma General ED on June 22nd and June 24th and at the St Joseph ED June 24th – 25th.

My colleagues and I at the Tacoma-Pierce County Health Department have been anxiously watching previous outbreaks of measles in Washington State and preparing for an outbreak in our jurisdiction.

On March 29th of this year, a Whatcom County resident with measles travelled to King and Pierce counties. That person's infection was linked to a large outbreak in Fraser Valley, British Columbia. Fortunately, no secondary cases of measles from those exposures were reported in either Pierce or King county.
The incubation period for measles is usually 1 to 3 weeks. A person with measles becomes contagious 4 days before developing a rash, that is, before that person has any signs or symptoms of measles.

For people who have not been vaccinated or those whose immunization status is unknown, measles vaccine can be given up to 72 hours after exposure to prevent measles or reduce the severity of the disease. For people who cannot receive measles vaccine or for people at high risk of complications from measles, immune globulin can be used up to 6 days after exposure to reduce the severity of disease.

In the United States, measles vaccine is usually not given to children less than one year of age. This is because maternal antibodies, which partially protect babies from measles, can interfere with the immune response to measles vaccine. Measles vaccine can be given as early as 6 months of age if a baby has been exposed to measles or in preparation for travel to a country in which measles is endemic. A dose given before 12 months of age does not count as that child's first dose, so that child should receive a dose at 12 to 15 months of age and 4 to 6 years of age.

The health department sent an alert to health care providers in Pierce County asking them to be on the lookout for cases of measles. Health care providers are required by state law to immediately notify the health department of suspected cases of measles. My colleagues and I at the health department are on call 24/7 to respond to those notifications.

Fortunately, most school children in Pierce County have received 2 doses of measles, mumps, and rubella (MMR) vaccine. The vaccine provides life-long protection against measles to more than 99% of people who receive two doses.

My previous posts on measles and related topics:
·       Measles
·       Attack ratios

Center for Disease Control and Prevention (CDC) information on measles and measles vaccine:
·       Measles (Rubeola)
·       Measles Vaccination
·       Pink Book


Centers for Disease Control and Prevention. (2013). Prevention of measles, rubella, congenital rubella syndrome, and mumps, 2013: summary recommendations of the Advisory Committee on Immunization Practices (ACIP). Morbidity and Mortality Weekly Report, 62(4), 1-34.




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