2002 Reportable Communicable Disease Summary

Giardia intestinalis, the flagellated protozoan also known as G. lamblia or G. duodenalis, is the most commonly identified parasitic pathogen in the US. Surveillance is essential to recognition of disease clusters, frequently associated with day-care facilities and community water systems.


Despite the fact that the majority of infections are asymptomatic, giardiasis is associated with a variety of gastrointestinal complaints, including chronic diarrhea, steatorrhea, abdominal cramps, bloating, frequent loose and pale, greasy stools, fatigue and weight loss. Children in day care and their close contacts are at greatest disease risk, as are backpackers and campers (by drinking unfiltered, untreated water), persons drinking from shallow wells, travelers to disease-endemic areas, and men who have sex with men. Giardia cysts can be excreted in the stool intermittently for weeks or months, resulting in a protracted period of communicability. Transmission occurs when cysts (as few as 10) are ingested through person-to-person or animal-to-person contact, or by ingestion of fecally contaminated water or food.


Despite a decade of decline in reported disease, Oregon?s rate remains above the national, with 12 cases per 100,000 population, 52% in males, and the majority of cases sporadic. Children <5 years old had the highest incidence with 36 cases/100,000, followed by adults 34?49 years with 15 cases/ 100,000.


Prevention depends upon good personal hygiene (hand washing!), and avoiding consumption of fecally-contaminated water. Travel warnings on water quality should be heeded.