Measles still poses threat to US, health officials warn

A patient receiving the measles vaccine. (REUTERS/Valentin Flauraud)

Although measles was officially "eliminated" in the United States in 2000, public health officials warned Thursday that the highly contagious, and sometimes deadly, virus continues to be imported from Europe and other parts of the world where the disease is still common. Despite high vaccination rates nationwide, measles continues to cause outbreaks in individual communities with large numbers of unvaccinated persons.

Between January 1 and August 24 of this year, the Centers for Disease Control and Prevention (CDC) received reports of 159 laboratory-confirmed measles cases. Federal health officials say all of the U.S. cases so far this year involve persons who either acquired the virus while traveling outside the U.S. or were exposed to an infected international traveler.

According to the CDC, at least 82 percent of the cases involved patients who had not been vaccinated. An additional 9 percent of the patients had unknown vaccination statuses.

Of the patients who had not received measles immunizations, 79 percent had philosophical objections to vaccination, federal health officials said.

Results of a National Immunization Survey released today show that 90.8 percent of U.S. toddlers between the ages of 19 and 35 months have received at least one dose of the measles, mumps and rubella vaccine (MMR) – just above the federal government's target of 90 percent. However, federal health officials warned that measles imported from other countries can still cause large outbreaks in the U.S., especially if introduced into areas with clusters of unvaccinated persons.

Such clusters can exist in homes, neighborhoods, schools or religious organizations, with heavy concentrations of people who are opposed to vaccination.

Such was the case in New York City back in March. An unvaccinated 17-year-old infected with measles returned from a trip to the United Kingdom and is suspected to be the source of the largest U.S. outbreak of the disease since 1996. Public health officials identified 58 measles cases in two Brooklyn neighborhoods, all involving people who had not been vaccinated.

Fortunately none of the U.S. cases this year has resulted in death, and CDC officials said all of the outbreaks of 2013 have been contained, thanks to high vaccination rates and rapid response by public health agencies. However, they continue to urge Americans to get vaccinated because the disease is easily transmitted.

"You can bring measles virus into an arena, and anyone who's not vaccinated in that arena who's never had measles is going to get that virus," said Dr. Anne Schuchat, director of the CDC's National Center for Immunization and Respiratory Diseases.

Since elimination in 2000, the largest number of U.S. measles cases was reported in 2011, with 220 people becoming ill.