Dog Parasite: Deadly Flatworm 'Heterobilharzia Americana' Discovered in Colorado River That Runs Through California

Dog parasites in the form of flatworms have been discovered along the banks of the Colorado River that runs through California. The discovery is based on a new study led by researchers from the University of California, Riverside, and the Naresuan University in Phitsanulok, Thailand. These deadly flatworms called Heterobilharzia americana, can cause the fatal parasitic disease known as canine schistosomiasis in dogs.

The recent research paper highlights the unprecedented spread of pathogens and the emergence of infectious diseases, affecting global health, the economy, and security risks. The authors of the study also emphasized the impact of climate change which can accelerate the dissemination of these superbugs, vectors, or hosts into new areas. In this context, the current climate crisis is contributing to the rise of pathogenic diseases.

Heterobilharzia Americana

The findings about the discovery of Heterobilharzia americana were published in the journal Pathogens Wednesday, March 13. In the paper, the US and Thailand research team confirmed the existence of the dog parasite on the West Coast, where it lives in two natural intermediate hosts found in the California part of the Colorado River. The dog-killing flatworms were found in southern California.

In the past, most specimens of H. americana have been found mostly in Texas and other Gulf Coast states. In light of the March 2024 study, the team confirms that their discovery of the deadly parasite in the Colorado River, California, is the first time on record. Specifically, the flatworms were found in their two hosts Gaiba cubensis, a species of air-breathing freshwater snail, and Galba humilis, a species of gastropods.

Although the parasites were found in their gastropod hosts, the danger lies in their potential to infect other living organisms, especially dogs. Once the flatworms infect our furry canine pets, it can bring the parasitic disease canine schistosomiasis mentioned earlier. In the US, the flatworm-borne disease is responsible for the deaths of infected dogs in the Southeast region, as well as in Texas and Louisiana, according to previous reports.

What is Canine Schistosomiasis?

Based on a news release by the UC Riverside on Thursday, March 14, experts warned dog owners about the risks of allowing their pets to swim along the Colorado River, due to the confirmed presence of Heterobilharzia americana. The researchers also emphasized canine schistosomiasis since it can impact the liver and intestines of dogs. According to UC Riverside nematology professor, Adler Dillman, the dogs can die from the infection.

In an August 2023 report, the LA County Department of Public Health stated there was a total of 11 cases of the dog parasite disease among pet dogs from three counties in southern California: Los Angeles County, Orange County, and Riverside County. These cases occurred between 2018 and 2023, a period when the infected dogs were believed to have been swimming in the Colorado River before being diagnosed.