Veterinarians Warn of Deadly Dog Parasite in Colorado River

Experts are warning dog owners of a deadly parasite that has been found in the Colorado River in Southern California for the first time.

University of California, Riverside scientists confirmed last week that this is the first time Heterobilharzia americana, a flatworm commonly referred to as liver fluke, has been discovered that far west.

​​“Dogs can die from this infection, so we are hoping to raise public awareness that it’s there,” UCR nematology professor Adler Dillman told the university’s newspaper. “If you’re swimming in the Colorado River with them, your pets are in peril.”

The worm is found in snails and can lead to canine schistosomiasis, an illness impacting the liver and intestines of dogs. It had previously only been found in Texas and other Gulf states, UCR scientists said.

After hearing of multiple California dogs getting infected, Dillman traveled down to the river with a team of researchers from the university. Upon collecting and testing 2,000 snails from the banks of the waterway, the scientists said they found “a wider distribution [of the parasite] than previously reported.”

“Our findings have implications for public health, veterinary medicine, and biodiversity conservation, contributing to developing effective control strategies to prevent the spread of this emerging infectious disease,” they said.

“Symptoms start gradually with a loss of appetite, and eventually include vomiting, diarrhea, profound weight loss, and signs of liver disease,” said Emily Beeler, a Los Angeles County Department of Public Health veterinarian.

If one’s dog experiences symptoms, Beeler encourages owners to take them to a veterinarian for monitoring and treatment.

Dillman added that the parasites don’t pose any major health threats to humans.