Little is known about cyclospora's life cycle, the ways it spreads, and whether birds or animals that feed on berries are involved. This means that experts have little idea how cyclospora reaches the berries, or whether humans are the only hosts. In many investigations of disease outbreak, information obtained in the initial stages turns out to be wrong. Epidemiologists are looking into the possibility that the initial warning against eating strawberries might have been premature. Another difficulty in the investigation is the nature of cyclospora.
Food histories are the backbone of the epidemiologic investigations.
But with cyclospora, the incubation period is about a week, longer than for many other food-borne infections. Additional days might pass before an infected individual seeks medical attention, laboratory tests are performed, and an accurate diagnosis is made. By then, many people have forgotten what they ate. Further, when asked about the preparation of food for a shared meal, food- handlers often have great difficulty remembering the source of the foods served two or more weeks in the past. Sellers at St. Lawrence Market in Toronto on Saturday found customers nervous about strawberries clearly labelled Ontario-grown.