International event led to U.S. measles outbreak

NEW YORK (Reuters Health) - Attendance at an international youth sporting event in the U.S. last year was linked to seven cases of measles, according to the Centers for Disease Control and Prevention.

The outbreak confirms the need for the highest possible levels of vaccination coverage in the US, CDC investigators emphasize in their report in the Morbidity and Mortality Weekly Report.

The initial case was a 12-year-old boy on a Japanese team who traveled to Pennsylvania in August 2007 to participate in the event. The boy, whose vaccination status was unknown, had been exposed to a sibling with a measles-like illness in July. Soon after arrival in the US, the boy developed a sore throat and other symptoms and was ultimately diagnosed with measles.

Exposure to the boy, directly or indirectly, gave rise to six other cases: one in Pennsylvania; two in Michigan, where the first boy changed planes; and three in Texas, where a salesman who had been at the sporting event later traveled. Five of the cases involved US residents, including an airport worker and an airline passenger.

In cooperation with state and local health departments, the CDC controlled the outbreak with measures that included identification and isolation of sick individuals and vaccination of those lacking immunity.

Exposure to measles, the report notes, can infect up to 90 percent of people who are not immunized against the virus. "Previous imported measles cases have demonstrated the potential for larger outbreaks in U.S. communities with poor vaccination coverage."

The small number of cases in this outbreak, despite the large number of people who were exposed, "demonstrates the value of maintaining high measles vaccination coverage in the U.S. population through adherence to routine vaccination recommendations," the authors state.

SOURCE: Morbidity and Mortality Weekly Report, February 22, 2008.