U.S. Measles Outbreaks Signal Need for Continued Push for Immunization

A series of measles outbreaks in nine U.S. states recently triggered a reminder from CDC officials that although the disease is no longer considered endemic in the United States, the measles virus still can be imported from other countries. According to a Morbidity and Mortality Weekly Report article published May 1, of a total of 64 cases reported to the CDC between Jan. 1 and April 25 -- the highest tally reported for this period since 2001 -- 54 have been associated with importation of the virus from foreign countries.

All but one of the 64 measles cases occurred in individuals who had not been vaccinated against the disease or whose vaccination status was unknown or undocumented; of the remaining 63 case-patients, 14 were infants too young to be vaccinated. Eighteen cases were reported among children ages 1-4 years, and 11 cases occurred in those ages 5-19 years. In many of these instances, the children's parents claimed exemption from vaccination due to religious or personal beliefs.

Disease transmission has occurred in various community and health care settings, including child-care centers, schools, hospitals, emergency rooms and physicians' offices. Although 14 patients were hospitalized with severe illness, no deaths have been reported.

A May 6 update posted on the CDC Web site says the situation illustrates the continued need for routine immunization against measles. "These cases remind us that it is important to vaccinate children and adults to protect them against measles," the update states. "Even though the ongoing transmission of measles was declared eliminated in the U.S. in 2000, the disease is still common in other parts of the world and can be imported into the U.S. from many countries, including countries in Europe."

It's advice family physicians should take to heart, says Jonathan Temte, M.D., Ph.D., of Madison, Wis., one of the Academy's two liaisons to the CDC's Advisory Committee on Immunization Practices, or ACIP. He and other participants at the ACIP's Feb. 27-28 meeting received a briefing on an outbreak of the disease that had recently taken place in San Diego. That particular outbreak, public health officials determined, was initiated by an index case imported from Switzerland.

In the San Diego outbreak, Temte says, all 12 cases occurred in unvaccinated individuals, two-thirds of them unvaccinated because of "personal exemption waivers." The outbreak prompted a significant public health response, with 70 children quarantined," he adds.

The good news in this case, according to Temte, is that "the 'wall of immunity' held fast and this contained this outbreak." But that should never be taken for granted, he adds.

"'Ancient'" diseases -- those that most family physicians have never seen due to the effectiveness of immunization programs -- continue to pose a threat," Temte says. "Personal exemption waivers for measles are associated with a 22- to 224-fold increase in likelihood of measles infection. Continued vigilance and encouragement of vaccination are needed to maintain the absence of measles."