Study finds 1 in 15 house cats carries beaver fever parasite

About one in 15 domestic felines across North America carries an intestinal parasite capable of sickening people, a study shows. The findings reveal that nearly one in five infected animals harbored strains that could potentially jump to human hosts.

The research examined more than 157,000 cats in the United States and Canada. Investigators confirmed 6.3 percent tested positive for Giardia duodenalis. The organism causes an intestinal illness commonly called beaver fever.

The study did not establish whether any feline transmitted the organism to an owner. PLOS One published the peer-reviewed report on Wednesday. Kittens under one year old faced the highest risk.

The team reviewed fecal samples collected between March 2022 and August 2023. Kittens posted an infection rate of 10.7 percent. Senior cats had a rate of 1.3 percent.

Younger cats have developing immune systems. They may also face higher contact with the pathogen. Male cats tested positive more often than females did.

Geography and calendar dates influenced the outcomes across North America. Technicians found the highest rate in the Midwest. The lowest rate occurred during summer.

The microscopic organism thrives in cold, wet settings. Infected felines sometimes suffer from diarrhea. Many show no signs.

The New York State Department of Health notes the organism spreads through fecal contact. People often ingest it via dirty water. Contaminated food and surfaces can also transfer it.

Sick people experience diarrhea, cramps, nausea, gas and dehydration. Exposure symptoms surface within one to two weeks. The illness persists for two to six weeks. Some individuals develop no symptoms.

Screening remains vital for households with young children, seniors or sick residents. Co-author Dr. Anne Kimmerlein shared recommendations with ABC News.

“Because some strains of Giardia can affect both animal and human health, understanding how commonly it occurs can help support earlier detection, appropriate treatment, and conversations about practical steps pet owners can take to help protect both their pets and their households,” Kimmerlein said.

Hand washing after scooping litter boxes lowers transmission risks. Thorough cleanup of animal waste also prevents spread. Positive tests require veterinary guidance for remedies and cleaning.

Public health departments issue hygiene advice to help residents avoid common waterborne and foodborne illnesses. These local agencies monitor regional disease patterns to provide basic guidance for households.

The study used samples submitted for veterinary testing across North America. Those results might not reflect rates in all pets. Scientists need more research on real transmission rates between animals and people.