DETROIT - Children who have fevers in their first year of life are less likely to develop allergies or asthma by ages 6 or 7, according to a Henry Ford Hospital study. The study, which appears in this month's Journal of Allergy and Clinical Immunology, found that 31 percent of children who had two or more fevers by age one developed allergies to pets, ragweed, grass and dust mites compared to 50 percent of children who had no fevers.

The study also showed that 1.5 percent of children who had two or more fevers by age one developed allergic asthma compared with 8 percent of children who had no fevers.

Reseachers found that fever was common among children in their first year of life. Of the 441 children evaluated by ages 6 or 7, 207 had a fever in their first year. Most fevers were associated with ear or respiratory tract infections.

Keoki Williams, M.D., a Henry Ford epidemiologist and the study's lead author, says the findings provide strong support for the hygiene hypothesis, which holds that exposure to infectious agents early in life protects against allergies and asthma. 'It appears from our study that fevers caused by infections help shape our early immune system so that we don't develop allergies,' Dr. Williams says.

Allergies are the sixth leading cause of chronic disease in the United States, affecting nearly 50 million children and adults. Asthma is the most common chronic childhood disease, affecting one in 20 children.

By ages 6 or 7, 441 children underwent clinical evaluation for allergies and asthma by a board-certified allergist. The evaluation included a blood test that measures the antibody (immunoglobulin E) that causes allergies, a skin reaction test that show whether a person is hypersensitive to an allergen, and pulmonary function testing.