GIARDIASIS IN COLORADO - EPIDEMIOLOGIC-STUDY

A 1-yr retrospective laboratory survey in Colorado [USA] revealed that 691 (3%) of 22,743 stool examinations for ova and parasites were positive for Giardia lamblia, a higher percentage than that reported from surveys outside of Colorado. Most infected residents who were surveyed experienced an episode of chronic watery diarrhea (median duration 3.8 wk) with bloating, flatulence and weight loss (averaging 5.1 kg), and responded to a course of metronidazole or quinacrine. A statewide telephone survey of 256 cases and matched controls identified: an increased incidence of giardiasis in persons aged 16-45, P < .001, with males and females equally affected; and a higher proportion of cases than controls who visited Colorado mountains (69% vs. 47%), camped out overnight (38% vs. 18%) and drank untreated mountain water (50% vs. 17%), P < .001. Also identified was a correlation between the seasonal distribution of cases and degree of fecal contamination of mountain streams. Evidently, G. lamblia is endemic in Colorado, and drinking untreated mountain water is an important cause of endemic infection.