Scientists are rushing to track rare parasite linked to berries Cyclospora is suspected in 1,000 cases of illness

July 06, 1996|By LOS ANGELES TIMES

WASHINGTON -- In the highly specialized world of microbiology, Dr. David Relman occupies an unusual niche: He drafts genetic blueprints of "novel organisms" -- disease-causing bugs that scientists have been unable to classify because they cannot be grown in the laboratory.

It is a relatively obscure pursuit. So no one was more surprised than the Stanford University researcher at the big news generated by the object of his latest scientific paper: a little-known parasite called cyclospora, which rarely turns up in the United States.

Today, the American public is getting a quick education in the workings of cyclospora, an exotic microbe that in recent weeks has emerged as the suspected cause of gastrointestinal illness in nearly 1,000 people in 11 states.

Federal and state health officials across the country are racing to find the source of the parasite, which they suspect is being spread through contaminated berries.

California produces 80 percent of the United States' strawberries, the suspect fruit that has generated the most speculation as source of the parasite. Florida produces roughly 10 percent, and the rest come from other states.

California health officials said they have turned up no traces of cyclospora after two weeks of testing strawberries, water and soil, and federal officials have been shifting their attention to raspberries and other fruits.

"We're not really prepared to say it's this berry vs. that berry," said Dr. Sue Binder, a top official at the U.S. Centers for Disease Control and Prevention in Atlanta. "We don't feel we can say confidently which fruit, or even which country or which farm."

The investigation is proceeding at a rapid clip. Working nights and weekends, dozens of federal and state epidemiologists are interviewing patients afflicted with cyclospora. FDA investigators are conducting "trace-back investigations," in which they examine records to trace suspected foods to their source of origin.

Tracking the cyclospora bug is tricky. First, the parasite does not produce symptoms until a week after infection. For medical pTC detectives, that lag time often means the trail has gone cold; patients don't remember what they ate a week ago and leftovers are rarely available for testing.

Second, testing for cyclospora is difficult. While common in developing countries, the organism has been identified only recently and had caused only three small outbreaks in the United States before the current epidemic.

Thus American scientists have paid scant attention to it, and sophisticated testing techniques such as one recently developed by Relman are not widely available.

The illness is treated easily with antibiotics but, if left untreated, it can cause severe diarrhea, lasting up to four weeks, as well as loss of appetite, nausea, vomiting, fatigue and low-grade fever.

Scientists say that transmission is usually through infected feces that contaminate water or food.

Pub Date: 7/06/96

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