A parasitic worm that can infect and kill dogs is discovered for the first time in the Colorado River in Southern California.

A group of scientists at the University of California, Riverside confirms the parasite’s existence in a report posted on Thursday, March 14.

The parasite, Heterobilharzia americana, is a flatworm more commonly known as liver fluke. According to the scientists, the parasite was previously found in Texas and other Gulf states.

“It has never been reported this far west,” they wrote.

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

After finding out that local dogs have been infected, Dillman and his research team headed to Blythe, California to collect more than 2,000 snails, because “the infection is driven by the presence of a snail that transmits the worm.”

“In our study, we successfully confirmed the presence of Heterobilharzia americana for the first time along the shores of the Colorado River, infecting two species of snails, Galba humilis and Galba cubensis,” the research team concluded in their study.

The worm will transform inside a snail and venture out with the goal of finding a mammal to infect.

The worm then penetrates the skin while a dog is swimming in contaminated fresh water sources. And it can cause a fatal disease called canine schistosomiasis, a disease that affects a dog’s liver and intestines.

“It gets into the veins of the intestinal lining, and that’s where it develops into an adult and mates,” Dillman told UC Riverside News.

“The presence of the adults in the veins isn’t the problem. It’s the eggs that get into the lungs, spleen, liver, and heart. The immune system tries to deal with it, and hard clusters of immune cells called granulomas form. Eventually the organ tissues stop functioning.”

Once a mammal is infected, it can take several months before the worst symptoms appear.

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

“If your dog has these symptoms after swimming in the Colorado River, it’s a good precaution to ask your veterinarian for a simple fecal test,” she added.

UC Riverside News also notes that since 2019, 11 dogs in three counties in California have been confirmed with schistosomiasis, and one has died.

It is also worth noting that the parasite is not capable of causing any disease to humans except for a swimmer’s itch.