Giardiasis

Alternative names:

giardia

Definition:

An infection of the small intestine caused by the protozoa, Giardia lamblia.

Causes, incidence, and risk factors:

Giardia outbreaks can occur in communities where water supplies become contaminated with raw sewage. It can be contracted by drinking water from lakes or streams where water-dwelling animals such as beavers and muskrats, or where domestic animals such as sheep, have caused contamination. It is also spread by direct person-to-person contact, which has caused outbreaks in day-care centers.

All travelers are at some risk of acquiring infection, but hikers drinking untreated surface water have the highest risk. Other risk factors include male homosexuality, exposure to a family member with giardiasis, and institutional (day-care or nursing home) exposure. The incidence of known cases is approximately 2 out of 10,000 people. It has been on the increase in the last few years.