Method Used to Track Unexplained Illness and Death Could More Quickly Identify New Infectious Diseases and Epidemics, Yale Researchers Find

A method called prospective surveillance, which studies unexplained illness and death due to possibly infectious causes, allowed for earlier detection of emerging and reemerging infections in 73 percent of cases, Yale researchers conclude in a new study.

“Before a new disease is identified and named, it can make countless people ill and even lead to death,” said study co-author Andre N. Sofair, M.D., assistant professor of medicine at Yale University School of Medicine. “Our approach provides clues to isolating an unknown disease, thereby allowing public health professionals to mobilize prevention efforts.”

As demonstrated by the emergence of West Nile, Lyme disease and AIDS, the United States is not impervious to emerging epidemics, said Sofair. Outbreaks of Ebola hemorrhagic fever in Zaire and plague in India in the early 1990s are reminders that emerging and reemerging infectious diseases remain a threat to the global community.

Published in the August issue of American Journal of Public Health, the study compared ongoing hospital-based surveillance (prospective surveillance) with retrospective surveillance, which reviewed hospital discharge data at seven New Haven County acute care hospitals in 1995 and 1996. The results revealed that 22 patients had either died or become seriously ill from what appeared to be an infectious disease.

Sofair said that although neither technique identified all cases of unexplained illness and death, prospective surveillance, a population-based surveillance network capable of identifying trends in symptoms of infectious disease, was 32 percent more sensitive than retrospective evaluation.

“Our results show that a systematic prospective study of the epidemiology of infectious disease syndromes is needed for earlier detection of and response to emerging infections,” said Sofair.

Other authors on the study include Michael D. Kluger, Constance J. Heye, James I. Meek, Rajesh K. Sodhi and James L. Hadler, M.D.

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