Study of nonoutbreak giardiasis: novel findings and implications for research.

BACKGROUND

The burden of nonoutbreak-related Giardia infections in the US is poorly understood, with little information on its impact on people's lives and on unusual manifestations of infection. This study was designed with the objectives of better defining the impact of infection, examining the occurrence of extraintestinal manifestations, and determining risk factors for delayed treatment of infection.

METHODS

Foodborne Diseases Active Surveillance Network surveillance was used to identify persons with nonoutbreak-related, laboratory-confirmed Giardia infection. People were enrolled into the Risk Factor arm and the Delayed Enrollment arm. Detailed questionnaires collected information on clinical manifestations, impact on activities of daily living, health care utilization, and treatment.

RESULTS

The study enrolled 290 people. Multivariate predictors of delayed study enrollment, a surrogate for delayed diagnosis of Giardia, included intermittent diarrheal symptoms, delayed time to first health care visit, and income. Decreased ability to participate in one's activities of daily living was reported by 210 (72.4%) participants. Appropriate therapeutic agent for Giardia was received by 237 (81.7%) by the time of study enrollment. Extraintestinal manifestations of Giardia were reported by 72 (33.8%) persons who enrolled in the Risk Factor arm.

CONCLUSIONS

The presence of intermittent diarrhea contributes to delayed health-seeking behavior and to delayed diagnosis of Giardia. More study is needed to determine if this symptom can help distinguish Giardia from other causes of infectious diarrhea. The occurrence of extraintestinal manifestations of Giardia infection does not appear to be rare, and merits further study.