Finding a measles-Crohn's disease link.

In one A.A. Milne poem, Christopher Robin comes down with wheezles and sneezles, and everyone wonders "if wheezles could turn into measles, if sneezles would turn into mumps." Now researchers say measles may turn into Crohn's disease, a painful intestinal disorder that strikes young adults.

For some children, exposure to the measles virus in the womb or soon after birth may result in Crohn's disease, scientists report in the Aug. 20 Lancet. Researchers estimate that the illness afflicts some 250,000 people in the United States.

Swedish investigators examined the incidence of Crohn's among people born between 1945 and 1954 in central Sweden during five measles epidemics. Children born during the peak month for measles cases during an epidemic and the 2 months afterward had a 46 percent greater chance of developing Crohn's than others born during the same decade, Anders Ekbom of University Hospital in Uppsala and his colleagues report.

They found 57 cases of the illness. That number should have been 39, according to the overall incidence rate for the decade. They counted only individuals who became sick prior to age 30, when the incidence rate is the highest. The team did not find an increased rate of colitis, another intestinal disorder, during the measles epidemics.

The people who developed Crohn's or their mothers may have had either a full-blown case of measles or a latent infection, Ekbom says. Other studies have shown that a measles epidemic increases the overall number of perinatal deaths, even when the mothers have received measles vaccinations, the Ekbom team notes. Investigators have also discovered particles of measles virus in the intestines of Crohn's patients.

The measles virus may quietly station itself in the gut early in life and not cause symptoms of Crohn's until after people mature and their immune systems change, says report coauthor Matthew M. Zack of the Centers for Disease Control and Prevention (CDC) in Atlanta. At that point, the body's defense apparatus may stop treating the virus like a benign visitor, suggests Zack. Children who develop the intestinal illness may have an unusual immune system to start with, he adds.

Crohn's victims may also have a genetic predisposition to the illness, the Ekbom team notes. Fifteen percent of Crohn's patients have a family history of the disease, says Theodore M. Bayless of John Hopkins University School of Medicine in Baltimore, who also studies the illness.

Bayless calls the Ekbom report "another piece of evidence that would fit the hypothesis" that measles contributes to Crohn's. He is not yet convinced the hypothesis is correct, but "I'm trying to keep an open mind," he says. Bayless notes the U.S. incidence of Crohn's has remained steady. Yet it should be declining if the disease has roots in measles, since measles immunization, begun in the early 1960s, has reduced the occurrence of measles.

However, new evidence suggests that vaccination may not prove strong enough to prevent latent infections that could lead to Crohn's. Some people immunized against measles as children have come down with the disease as adults, prompting the CDC to recommend two measles shots.