U.K. measles outbreaks pose risk to U.S.

By STEVE MITCHELL, Medical Correspondent  |  Oct. 31, 2003 at 5:35 PM
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WASHINGTON, Oct. 31 (UPI) -- As the United Kingdom braces for an impending measles outbreak this winter due to low vaccination rates, U.S. health experts say this raises concerns the deadly disease could spread to the United States, particularly considering immunization rates in some states have fallen to dangerously low levels.

The drop in measles vaccinations also heightens fears of outbreaks of two other diseases: rubella and mumps. This is because the measles vaccine generally is administered in conjunction with mumps and rubella inoculations in a single shot known by the corresponding initials, MMR. So a drop in measles protection is a drop in rubella and mumps protection as well.

Of the three diseases, measles carries the most concern because it is a highly contagious disease with a death rate of one or two children for every 1,000 infected. It also can cause other serious complications, including pneumonia, swelling of the brain and seizures.

The major rubella worry is if it infects women when they are pregnant, then it can cause birth defects in their developing fetus -- including deafness, eye defects, heart abnormalities and mental retardation.

"A resurgence in measles in the United Kingdom could translate to exposure here," Dr. Walter Orenstein, director of the Centers for Disease Control and Prevention's National Immunization Program in Atlanta, told United Press International. He noted the concern is compounded by the fact that "the chief source of measles in the United States used to be the (United Kingdom)."

In addition to the expected U.K. measles rise, health officials also are worried about the ongoing outbreak in the Marshall Islands and recent epidemics in Asia and Italy. In an effort to reduce the threat posed to the United States, CDC officials are collaborating with international authorities to keep measles in check in other countries as well as making efforts to keep vaccination rates high domestically.

Dr. Diane Griffin, chair of the department of molecular microbiology and immunology at Johns Hopkins University's Bloomberg School of Public Health in Baltimore, agreed the outbreaks in other areas of the world pose a risk to the United States.

"There is continued importation of measles from all these different parts of the world," including Japan and Europe, Griffin told UPI. "This means there are more cases that are likely to be imported ... and our immunization will continue to be tested."

This prospect concerns health officials because vaccination rates in some states and cities have dropped to levels that would allow an outbreak of measles to be sustained if a case gets into the community. This could have severe consequences as evidenced by measles outbreaks in the United States between 1989 and 1991, mainly among unvaccinated, preschool-aged children that infected more than 55,000 people and resulted in 123 deaths.

Vaccination rates in the United Kingdom for the MMR vaccine have dropped to the lowest level in at least eight years, primarily due to unfounded concerns by parents that the vaccine is linked to autism. The lowered immunization rates already appear to be leading to increases of mumps, rubella and measles.

In Scottish children under age 15, suspected cases of measles have jumped by 18 percent in the last 18 months -- and rubella by 22 percent and mumps by 27 percent -- according to statistics released earlier this week by the National Health Service of Scotland. Most of these cases will turn out to be due to other causes but the trend does suggest the diseases are on the increase.

The concern about a widespread outbreak in the United Kingdom has reached such high levels it has prompted a pediatrician -- who conducted the study that initially raised alarm about the possibility of a link between the MMR vaccine and autism -- to recant his position in a letter to a medical journal and urge parents to get their children inoculated.

"There is now unequivocal evidence that MMR is not a risk factor for autism -- this statement is not spin or medical conspiracy, but reflects an unprecedented volume of medical study on a worldwide basis," Simon Murch, a pediatrician with the Royal Free and University College Medical School in London, writes in the Nov. 1 issue of The Lancet.

"Unless vaccine uptake improves rapidly, major measles epidemics are likely in the (United Kingdom) this winter," warns Murch who co-authored a 1998 study in The Lancet, along with Andrew Wakefield -- also of the Royal Free Hospital -- which sparked the concern the MMR vaccine could cause autism. Wakefield has continued to propagate the unsubstantiated autism concern and ultimately lost his job over the controversy.

The current rate of MMR vaccine coverage in the United Kingdom stands at about 86 percent, but Murch notes in his letter that in some areas the coverage rate has dropped as low as 61 percent. Health officials think a vaccine coverage rate of about 95 percent is necessary to prevent outbreaks and anything below 90 could allow outbreaks to flourish.

In the United States, MMR vaccine coverage is about 91.6 percent, but "we hear anecdotal reports of lower coverage in certain areas," CDC's Orenstein said.

Several areas have rates of only 87 percent or lower, including Arizona (except for Maricopa County), Montana, Oklahoma, Oregon, Shelby County, Tenn., Houston and parts of Colorado.

Some states have vaccination rates below the 90 percent mark, including Alaska, most of California, Idaho, Kentucky, Louisiana, Nevada, Washington and Wyoming. The numbers are averages for these whole states, so there could be pockets where the coverage rates are much lower, Orenstein said. Even if some local populations have only 50 percent immunization coverage, they could be overlooked within an average of 91 percent for the whole state, he explained.

Keeping the immunization coverage uniformly high is essential because an increasing number of unvaccinated people makes it easier for a case of measles to take hold and, in turn, boost the likelihood of spreading the disease to vaccinated individuals -- because no vaccine confers 100 percent protection.

"The real threat is the same thing that has driven down immunization rates in the United Kingdom and Japan and that is parental resistance to having their children immunized," Griffin said.

In Colorado, for example, there are communities "where close to 20 percent of kids are not immunized," she said. "All you need is the introduction of a case and since its constantly happening in the United States all you need is a case to occur in those vulnerable communities" for an epidemic to take hold, she said.

To make matters worse, "there is concern among the public health community that parental resistance to vaccines is increasing" in the United States, Griffin said.

In the Marshall Islands measles outbreak that began this summer and has resulted in 752 cases and three deaths, the vaccination coverage was about 75 percent. This is of concern because people infected in that outbreak are known to have traveled into the United States, Dr. Martin Myers, executive director of the National Network for Immunization Information in Alexandria, Va., told UPI.

Mexico also recently had measles cases imported from Asia and this could easily spread across the border into the United States, he added.

"The potential for introduction into the United States is substantial," Myers said.


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