INFECTIONS MAY BLOCK ASTHMA IN CHILDREN : BY RICHARD A. KNOX THE BOSTON GLOBE.A rise in childhood asthma in many countries may stem, paradoxically, from better health among children rather than increased air pollution or environmental hazards, researchers in Japan and Britain hypothesize hy·poth·e·size v. hy·poth·e·sized, hy·poth·e·siz·ing, hy·poth·e·siz·es v.tr. To assert as a hypothesis. v.intr. To form a hypothesis. in articles published Friday. The idea, which United States asthma experts called intriguing but unproven, is that childhood respiratory infections may protect against asthma by shifting the balance of certain immune system immune system Cells, cell products, organs, and structures of the body involved in the detection and destruction of foreign invaders, such as bacteria, viruses, and cancer cells. Immunity is based on the system's ability to launch a defense against such invaders. cells. Children who have had more infections may have fewer immune cells of the type thought to trigger the wheezing Wheezing Definition Wheezing is a high-pitched whistling sound associated with labored breathing. Description Wheezing occurs when a child or adult tries to breathe deeply through air passages that are narrowed or filled with mucus as a and airway constriction constriction /con·stric·tion/ (kon-strik´shun) 1. a narrowing or compression of a part; a stricture.constric´tive 2. a diminution in range of thinking or feeling, associated with diminished spontaneity. of an asthma attack, some researchers think. The hypothesis gains support from a study of about 900 Japanese teen-agers who had been inoculated with tuberculosis vaccine tuberculosis vaccine n. See BCG vaccine. , which fools the body into thinking it has encountered an actual TB infection. The researchers found that the vaccinated children who later responded positively to a TB skin test - showing the vaccine had ``taken'' - had one-third to one-half the incidence of asthma compared to the 40 percent of children in whom the vaccine did not take. They also had half as much eczema, a skin rash that shares some of the same immune mechanisms as asthma. ``The data support the hypothesis that a decline in infection, in this instance tuberculosis, is a factor underlying the rising severity and prevalence'' of asthma in developing countries, wrote Taro Shirakawa and colleagues at Churchill Hospital in Oxford, England, and others at the Japanese Red Cross Society and hospitals in Wakayama, Japan. Their paper appears in the American journal Science. Asthma prevalence has doubled in the last 20 years in westernized west·ern·ize tr.v. west·ern·ized, west·ern·iz·ing, west·ern·iz·es To convert to the customs of Western civilization. west societies, noted William O.C.M. Cookson and Miriam F. Moffatt of Oxford University in a companion paper in Science. Asthma causes one-third of U.S. pediatric pediatric /pe·di·at·ric/ (pe?de-at´rik) pertaining to the health of children. pe·di·at·ric adj. Of or relating to pediatrics. emergency-room visits. The Japanese study suggests that ``asthma prevalence has increased because of something lacking in the modern environment, rather than through the positive actions of some toxic factor,'' wrote Cookson and Moffatt. ``Childhood infections may . . . paradoxically protect against asthma.'' |
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