# Canine Schistosomiasis in the West Coast: Heterobilharzia americana in Two Natural Intermediate Hosts Found in the Colorado River, California

## TL;DR

This study reports the first discovery of Heterobilharzia americana, a parasitic worm, in two snail species along California's Colorado River, highlighting its public health and ecological implications.

## Contribution

The study identifies the first occurrence of H. americana in California and confirms its presence in two new intermediate host snail species.

## Key findings

- Heterobilharzia americana was found in Galba cubensis and Galba humilis snails along the Colorado River.
- DNA sequencing and phylogenetic analysis confirmed the presence of H. americana in California.
- The findings suggest a broader geographic distribution of the parasite than previously known.

## Abstract

The emergence of infectious diseases presents a significant global health, economic, and security risk. Climate change can unexpectedly lead to the spread of pathogens, vectors, or hosts into new areas, contributing to the rise of infectious diseases. Surveillance plays a crucial role in monitoring disease trends and implementing control strategies. In this study, we document the first discovery of Heterobilharzia americana, a parasitic schistosome of mammals and its intermediate hosts Galba cubensis and Galba humilis along the banks of the Colorado River in California. We conducted multiple samplings of snails from various locations in the region with a previous history of canine schistosomiasis. Nucleotide sequencing of the multiple regions of the snails’ and parasites’ DNA revealed the coexistence of G. cubensis and G. humilis, both infected with H. americana. Phylogenetic analyses further validate the presence of H. americana in California, suggesting a wider distribution than previously reported. Our findings have implications for public health, veterinary medicine, and biodiversity conservation, contributing to developing effective control strategies to prevent the spread of this emerging infectious disease.