Peruvians Sick of El Niño

Peruvians Sick of El Nifio As Peruvian officials braced for the effects of El Ninio in 1997, they suspected they might be hit with a rash of diarrhea cases. They were correct, as the diarrhea caseload in children doubled during the worst stretches of a 16-month period of above-average temperatures. An international team of researchers led by William Checkley, a researcher in the Department of International Health at the Johns Hopkins School of Public Health and a medical student at Northwestern University, has concluded in a study published in the 5 February 2000 issue of The Lancet that higher temperatures triggered a diarrhea outbreak in Lima. The study is one of the first to statistically support the longsuspected link between diarrhea and temperature. Diarrhea annually kills about four million people worldwide, mostly children. The warming effects of El Nifio were felt in Lima, a metropolitan area of about eight million people, from May 1997 through August 1998. The team compared selected data on hospital admissions and climate factors for the El Nifio period to comparable data from 1993 to 1996. During the time for which data were reviewed, 57,331 children under age 10 who were suffering from diarrhea of undetermined cause were admitted to the Oral Rehydration Unit of the 600-bed Instituto de Salud del Nifno, Lima's largest public hospital for children. The team found that the historical pattern of diarrhea cases in the Southern Hemisphere-higher in summer Uanuary-March) and lower in winter Uuly-September)---continued during the El Niflo period. But hospital admissions jumped about 20% higher than normal during the summer and up to 100% higher during the winter, leading to an estimated 6,225 more cases than normal during the El Nifno period. In the peak summer and winter months of 1997-1998, mean ambient temperatures increased up to 5°C (9°F) above normal. Along with temperature, the team investigated a possible link with humidity, which averages an unusually high 84% in Lima's coastal setting. They found it was inextricably linked with temperature, with falling humidity strongly correlated with rising temperature. Although the researchers speculated about the greater increase in cases of diarrhea in winter, they could not statistically test their hunches about which biological or behavioral factors may have contributed to the greater winter incidence. The team did inquire about some year-round factors other than climate that may have boosted the diarrhea caseload, which increased 8% for each 1°C (1.8°F) rise in temperature, even in the pre-El Ninlo years. But local health officials said there had been no changes on their part in preventive or educational efforts, and unpublished community data suggest that people were not seeking treatment at a higher rate. The team acknowledges that some potential explanations, such as less-conscientious hygiene and changes in patterns of food availability, remain untested. And Lima's climate, where the data were collected, is distinctive enough that the same pattern may not hold up elsewhere. "It's an interesting finding that needs further study before it can be assumed to apply to other locations," says Janice Longstreth, a toxicologist and president of The Institute for Global Risk Research. -Bob Weinhold