Measles cases in U.S. down, but many were preventable

Public health officials are sounding an alarm because, although the national number of measles cases is at an all-time low, a significant tally of them appear to be preventable.

A new study, published in the Aug. 26 Morbidity and Mortality Weekly Report, found that of the 251 cases occurring between 2001 and 2004, 100 could have been prevented because they occurred among U.S. residents who fall within groups recommended to receive the vaccine. These people who were unprotected then either traveled to areas where the disease is endemic or had contact with someone who did.

"This is something we need to worry about," said Alison Rue, MPH, lead author and an officer in the Centers for Disease Control and Prevention's Epidemic Intelligence Service. "Measles is still a risk."

Physicians called attention to the significant work that has made these numbers so low but also pointed out that it may still be possible to reduce further the incidence.

"There's a lot of good news in the paper," said Jonathan Sugarman, MD, MPH, a family physician and president of Qualis Health, a quality improvement organization in Seattle. "But it also serves as a reminder that in the crush of things to do, measles vaccine is really important, and we need to keep measles on the radar screen for travelers."

Experts note, however, that there are significant barriers to more progress in lessening the number of preventable cases among adults and children.

For adults, one such hurdle is the lack of attention paid to vaccinations for this age group.

Even if adults received what was considered the full set of childhood vaccinations in their youth, they now might not be as immune as they think. Specifically, they might have received only one measles vaccine shot rather than the currently preferred two.

"It's always good to come in for a check-up and review immunizations cards," said Aileen Buckler, MD, MPH, deputy state epidemiologist for the Iowa Dept. of Public Health. "But people don't think about that for adults." Iowa had a measles outbreak in the spring of 2004 linked to adults who were unvaccinated for religious reasons.

A lack of vaccination also can be a result of the lack of attention to some of the dangers associated with travel to even the most developed areas of the world. Of the 55 preventable cases occurring in those older than 20, 15 were linked directly to international travel, and some of those were linked to areas of the world not traditionally viewed as dangerous with regard to infectious disease.

The Seattle and King Country public health department reported a confirmed measles case in August that involved a man in his 40s who had traveled to France. It appears that he was never vaccinated.

"No one ever checked whether he was immune to measles, and no one ever bothered to find out whether he traveled," said Jeff Duchin, MD, chief of the communicable disease control program at the Seattle and King County Dept. of Public Health. "He traveled frequently."

Vigilance required

The preventable cases in infants present different challenges. Those 6 to 12 months old are not usually recommended to receive the measles vaccine until they are at least 1 year old. They should receive it, though, if they are traveling to areas where the disease is endemic. Additionally, they will still need the usual two-shot vaccination after age 1. Experts say few physicians or other vaccine providers are aware of this provision.

"The recommendation that young children who travel should get the shot is not well-known," said Dr. Buckler, who vaccinated one of her children early because she moved to Iowa while it was having the outbreak. "I didn't know until I was working in public health."

Despite these challenges and the fact that measles has become such a rare event, experts say even these low numbers are a cause for concern. "We can't let our guard down," said Margie Andreae, MD, associate professor in the division of general pediatrics at the University of Michigan Health System in Ann Arbor.

Even a single case can be very expensive for the public health departments that have to contain it. A study published in the July issue of Pediatrics concerning the Iowa outbreak -- which involved three confirmed cases -- estimated that the situation cost more than $140,000 and more than 2,500 hours of public health personnel time.

"There are hundreds and hundreds of people who were exposed who need to be contacted," said Dr. Duchin. "It's a tremendous amount of labor."

In addition to the public health cost, the virus can cause significant illness and even death in infants or those with compromised immune systems. Experts also warn that the disease could easily increase, citing the 1989-1991 epidemic during which 55,000 cases and more than 100 deaths occurred -- offering a reason for constant vigilance.

"We were quite surprised by how severe the cases were [from 1989 to 1991]," said Walter A. Orenstein, MD, associate director of the Emory Vaccine Center at Emory University in Atlanta.

Public health officials are urging physicians to make talking about travel a more routine part of care. But they also recognize that such steps will only go so far. They say a global perspective is also needed. As numbers diminish in other countries, so will the numbers here. For example, almost no cases are currently imported from Latin America, which used to be a major source of the disease, primarily because of significant vaccination efforts there.

"The thing that's more alarming is that cases in industrialized nations are actually increasing," Dr. Andreae said. "That puts us at greater risk. We can cut our rate in half, but it will take some collaboration at the level of the WHO or UNICEF to get the rates down in other countries."