An outbreak of cyclosporiasis in Florida in 1995: a harbinger of multistate outbreaks in 1996 and 1997

Abstract

Before 1995, only one outbreak of cyclosporiasis had been reported in the United States. To identify risk factors for Cyclospora infection acquired in Florida in 1995, we conducted a matched case-control study (24 sporadic cases and 69 controls) and retrospective cohort studies of clusters of cases associated with two May social events (attack rates = 15.4% [8 of 52] and 54.5% [6 of 11]). In univariate analysis of data from the case-control study, consumption of fresh raspberries (odds ratio [OR] = 6.0, 95% confidence interval [CI] = 1.1-31.7) and bare-handed contact with soil (OR = 5.4, 95% CI = 1.4-20.7) were associated with infection; soil contact was also implicated in multivariate analysis. For the events, mixed-fruit items that had only fresh raspberries and strawberries in common had elevated relative risks (3.7 and 4.2), but the confidence intervals overlapped 1.0. The raspberries eaten at the events and by sporadic case-patients were imported. Given the cumulative evidence of the three studies and the occurrence in 1996 and 1997 of outbreaks in North America associated with consumption of Guatemalan raspberries, food-borne transmission of Cyclospora was likely in 1995 in Florida as well.