Giardia parasite found in North American domestic cats

A large-scale study of over 157,000 fecal samples from domestic cats in the United States and Canada has revealed a significant presence of the Giardia duodenalis parasite. The research, published in the journal PLOS One, found that 6.3% of the tested animals had active infections.

Crucially, the study identified that 18.5% of these infected cats carried genetic groups A and B. Unlike the more common group F, which is specific to animals, groups A and B are known to pose a zoonotic risk, meaning they can be transmitted to humans. Infection in humans can lead to symptoms such as acute abdominal pain, chronic diarrhea, nausea, and general weakness.

The study also noted age-related differences in prevalence: 10.7% of kittens tested positive, compared to only 1.3% of older cats. Researchers warned that many infected cats may appear completely healthy and asymptomatic while still shedding the parasite, making regular preventative testing essential, particularly in households with young children, the elderly, or immunocompromised individuals.