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Giardiasis

Many wild and laboratory animals serve as a reservoir for Giardia spp., although cysts from human sources are regarded as more infectious for humans than are those from animal sources. Dogs, cats, and nonhuman primates are most likely to be involved in zoonotic transmission. According to recent surveys of endoparasites in dogs, the prevalence of Giardia generally ranges from 4 to 10%, and approaches 100% in some breeding kennels.

Giardiasis is transmitted by the fecal-oral route chiefly via cysts from an infected person or animal. The organism resides in the upper gastrointestinal tract where trophozoites feed and develop into infective cysts.

Humans and animals have similar patterns of infection. Infection can be asymptomatic, but anorexia, nausea, abdominal cramps, bloating, and chronic, intermittent diarrhea are often seen. Although the organism is rarely invasive, severe infections can produce inflammation in the bile and pancreatic ducts, and damage the duodenal and jejunal mucosa, resulting in the malabsorption of fat and fat soluble vitamins.

Identification and treatment of giardiasis in a laboratory animal host, in combination with effective personal hygiene, measures should reduce the potential for zoonotic transmission in a laboratory animal facility.