Researchers are cautioning pet owners in California to keep their dogs away from rivers this summer following the discovery of a potentially lethal worm species in the area for the first time.
In a recent press release from the University of California, Riverside, scientists revealed that a parasite previously confined to “Texas and other Gulf Coast states” has now migrated to the West Coast, posing a threat to local wildlife and pets.
The parasite, scientifically known as Heterobilharzia americana or liver fluke, is a flatworm transmitted by snails and capable of surviving up to 24 hours before attaching to a host.
According to the press release, the presence of the flatworm can lead to canine schistosomiasis, a condition affecting dogs’ liver and intestines, which can be fatal. “Dogs can die from this infection, so we are hoping to raise public awareness that it’s there,” stated UCR nematology professor Adler Dillman. “If you’re swimming in the Colorado River with them, your pets are in peril.”
The professor and his research team observed sick canines in Blythe, a town near Joshua Tree National Park in Riverside County, after the dogs had been exposed to rivers in the area. They collected over 2,000 snails and published their findings in the journal Pathogens on March 13.
“We actually found two species of snails that can support H. americana in the river in Blythe, and we found both snails actively shedding this worm,” Dillman noted. “Not only was it a surprise to find H. americana, we also did not know that the snails were present here.”
Aside from domestic pets, the parasite can infect various mammals, including raccoons, marsh rabbits, horses, and more. Once inside the host, the parasite can cause serious damage to vital organs.
“It gets into the veins of the intestinal lining, and that’s where it develops into an adult and mates,” explained Dillman. “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.”
Symptoms of infection in animals may include loss of appetite, vomiting, diarrhea, weight loss, and signs of liver disease. Veterinarian Emily Beeler advised pet owners whose animals have been in the Colorado River and display such symptoms to seek veterinary care promptly.
While the parasite can cause significant health issues in animals, humans are not susceptible to the same risks. “It can cause swimmer’s itch, a red rash where it penetrates human skin. But it’s not able to cause infection,” clarified Dillman.
