Infectious Disease Epidemiology Program

Giardiasis summary

Giardiasis is sometimes known as “beaver fever” because beavers (as well as dogs, cats, horses and cows) are major reservoirs for the parasite that causes the infection. The parasite lives in the intestines of infected humans and animals and when expelled through the feces can contaminate water and ground surfaces. The beaver feces can infect ponds and streams and if hikers or others drink water in the wild without proper treatment they may become infected. Young children in child care or pool settings who are prone to sucking on toys or swallowing water are also at higher risk.

Giardiasis is the most common infectious diarrheal illness reported in Maine. There were 197 cases reported in 2007, a slight increase from 2006. All of the counties reported cases with the highest rates in Franklin (26.7 per 100,000 population), Somerset (25.2 per 100,000 population), and Cumberland (22.2 per 100,000 population).

Giardiasis tends to occur more frequently in the summer and fall months with twice the number of cases identified in August and September than other months of the year. There was a near even split by gender with fifty-one percent of cases being female. The median age was 37 years old.

Individuals can prevent this illness by not drinking from untreated water sources such as streams and lakes. Increased attention to proper sanitation and hygiene in public water recreational facilities can help to reduce the transmission of this infection.