Abstract

Cryptosporidium spp. and Giardia spp. are ubiquitous, highly infectious protozoal parasites that have been identified in humans and in numerous species of domestic animals and wildlife. Infected humans and animals shed millions of environmentally stable infectious oocysts, making environmental contamination a concern. Within the inland waters of Washington State (Puget Sound and Northwest Straits), river otters (Lontra canadensis) forage in marine waters where they eat numerous species of fish and invertebrates and play an important role in the nearshore marine ecosystem. We evaluated marine-foraging river otters as regional sentinels for environmental contamination with Cryptosporidium spp. and Giardia spp. Fresh river otter scat samples were collected from shoreline latrine sites throughout the inland waters and tested for Cryptosporidium spp. and Giardia spp. oocysts via immuno-magnetic separation and fluorescent antibody testing. Cryptosporidium-like and Giardia-like oocysts were identified in a small percentage of samples and identification of these parasites to species is pending. Preliminary evidence suggests that river otters may be good sentinels of environmental contamination with these protozoal parasites. A larger sample size and a better understanding of the home range of these animals in this marine ecosystem are warranted.