Scientists at the University of California Riverside (UCR) have made a startling discovery, as they found dog-killing worms in Southern California for the first time. The team revealed that Heterobilharzia americana, a flatworm commonly referred to as liver fluke, is being transmitted by snails living along the Colorado Riverbed.

Previously, these harmful worms were only found in Texas, Louisiana, and Florida, but now their presence in Southern California suggests a broader expansion than previously known. The researchers at UCR collected over 2,000 snails from the region and identified two species, Galba cubensis and Galba humilis, harboring the flatworms.

Canine schistosomiasis is the illness caused by these worms, impacting the liver and intestines of dogs. The Los Angeles County of Public Health confirmed 11 cases of canine schistosomiasis spanning from 2018 to 2023. The UCR team discovered that all 11 dogs had spent time swimming in a region of the Colorado River, indicating possible transmission in the water.

Dr. Adler Dillman, a nematology professor at UCR, emphasized the urgency of raising public awareness about this infection. "Dogs can die from this infection, so we are hoping to raise public awareness that it's there," he said. If pet owners are swimming in the Colorado River with their dogs, their pets are at risk.

The discovery of the liver fluke in the snails along the Colorado Riverbed has caught researchers by surprise. While Galba cubensis was previously believed to be the only natural host of the worm, the presence of Galba humilis, which was previously thought to have only marginal susceptibility, was unexpected.

Once the liver fluke worm transforms inside a snail, it ventures out to find a mammal to infect. In this stage, the worm can only survive on its own for about 24 hours. If a dog or a raccoon is in the water, or drinking from it, they can become infected.

The researchers suggested that the parasite could be spreading throughout the Colorado River and the smaller rivers that feed into it, using these waterways to find new hosts. The study highlights the need for comprehensive investigations along the banks of the Colorado River and its tributaries in the United States and Mexico to understand the extent of the parasite's infection.

Symptoms of canine schistosomiasis start gradually, including a loss of appetite and eventually leading to vomiting, diarrhea, profound weight loss, and signs of liver disease. Dog owners are advised to seek a simple fecal test from their veterinarian if their pet exhibits these symptoms after swimming in the Colorado River.

Treatment for infected dogs typically involves multiple medications and close monitoring by a veterinarian. It should be noted that H. americana is not known to cause disease in humans, although it can cause swimmer's itch, a red rash when it penetrates human skin. However, the worms can be easily filtered out of water systems.

With this discovery of dog-killing worms in Southern California, it is vital for pet owners to be cautious when allowing their dogs to swim in the Colorado River and to seek proper veterinary care if their pets show any symptoms related to this illness. Public awareness and preventative measures are crucial in combating this serious threat to our canine companions.