About 1 in 16 cat stool samples tested at a large commercial veterinary lab contained Giardia, a gut parasite that causes diarrhea. A study of U.S. and Canadian cats in PLOS ONE, published Oct. 7, found the parasite in 9,962 of 157,616 samples, or 6.3%.
For households with a cat, especially those with young children or a new kitten, the more relevant number is smaller. Among the positive samples, 18.5% carried assemblages A and B, the genetic types of Giardia that can also infect people. Cats more often carry a cat-specific type known as assemblage F. The illness Giardia causes, giardiasis, is sometimes called "beaver fever", and it can spread through contaminated water.
