Beaver fever in U.S., 1971–2011

My friend was at his cabin near Algonquin Park (that’s in Canada) and twittered that his wife wanted to know if it was OK to use stream water to boil potatoes. said sure, as long as you don’t mind the beaver poop.

We’ve had a long tradition of don’t eat poop, but if you do, make sure it’s cooked.

Giardia intestinalis is the leading parasitic aetiology of human enteric infections in the United States, with an estimated 1·2 million cases occurring annually. To better understand transmission, we analysed data on all giardiasis outbreaks reported to the Centers for Disease Control and Prevention for 1971–2011.

The 242 outbreaks, affecting ~41 000 persons, resulted from waterborne (74·8%), foodborne (15·7%), person-to-person (2·5%), and animal contact (1·2%) transmission. Most (74·6%) waterborne outbreaks were associated with drinking water, followed by recreational water (18·2%). Problems with water treatment, untreated groundwater, and distribution systems were identified most often during drinking water-associated outbreak investigations; problems with water treatment declined after the 1980s. Most recreational water-associated outbreaks were linked to treated swimming venues, with pools and wading pools implicated most often. Produce was implicated most often in foodborne outbreaks. Additionally, foods were most commonly prepared in a restaurant and contaminated by a food handler.

giardia-posterLessons learned from examining patterns in outbreaks over time can help prevent future disease. Groundwater and distribution system vulnerabilities, inadequate pool disinfection, fruit and vegetable contamination, and poor food handler hygiene are promising targets for giardiasis prevention measures.

Giardiasis outbreaks in the United States, 1971–2011


Epidemiology and Infection


E.A. Adam, J.S. Yoder, L.H. Gould, M.C. Hlavsa, and W. Gargano