A warning for dog owners: keep your pets out of local rivers this season.

New research from the University of California, Riverside found what they’re calling a “dog-killing parasite” lurking in parts of the Colorado River running close to the Coachella Valley.

The parasite, Heterobilharzia americana, was previously found in Texas and other Gulf Coast states but has been reported out West for the first time.

The flatworm was found in sick dogs that were swimming in the river in Blythe, California in Riverside County. Researchers say it’s transmitted to dogs through infected snails.

Symptoms start gradually with a loss of appetite, and eventually include vomiting, diarrhea, profound weight loss, and signs of liver disease.

The parasite is not known to be capable of causing disease in humans but can cause swimmer’s itch; a red rash where it penetrates human skin.

Experts we spoke with say they are working to find out the extent of this parasite’s range.

“It certainly is still a danger for pets in this area and maybe further north in the Colorado River as well. That remains to be seen,” said Adler Dillman, Professor of Parasitology & Nematologist and Chair of the Department of Nematology at the University of California, Riverside.

Dillman says since 2019 in California, 11 dogs in three counties have been confirmed with this disease, and one has died.

If your pet does get infected, it can be treated and taken care of.

This story was written and reported by Kai Beech.

“Dog-killing parasite” discovered in Southern California