Researchers have discovered Echinococcus multilocularis, a potentially deadly tapeworm, infecting wild coyotes in the Pacific Northwest for the first time. Scientists testing animals around Puget Sound found the parasite in 37 percent of coyotes sampled, an alarmingly high prevalence for a region with no previous recorded cases in wildlife.
The tapeworm causes alveolar echinococcosis, a severe disease that mimics cancer and develops slowly in human hosts. Infection occurs when people ingest eggs shed in animal feces, typically through contaminated food, water, or direct contact with infected animals. Once established in humans, the parasite forms lesions primarily in the liver that can spread to lungs and brain, often proving fatal without aggressive treatment.
The presence of E. multilocularis in coyotes near Puget Sound represents a significant range expansion for the parasite on the U.S. West Coast. The tapeworm has established populations in the northern Great Plains and upper Midwest, where it infects coyotes, foxes, and other canids that serve as definitive hosts. Small mammals like rodents act as intermediate hosts, completing the parasite's life cycle.
The high infection rate in Pacific Northwest coyotes raises public health concerns. People who handle or hunt infected animals face direct exposure risk. Outdoor workers, hunters, and those with frequent wildlife contact need heightened awareness of potential exposure through contaminated hands or equipment.
Treatment for alveolar echinococcosis requires prolonged anthelmintic medication and often surgical intervention to remove lesions. Early detection improves outcomes substantially, but many infections progress asymptomatically for years before symptoms emerge.
Public health officials recommend standard precautions including handwashing after outdoor activities and before eating, avoiding contact with wild animal carcasses, and preventing pets from consuming small