The deadly tapeworm spreading across America has reached the Pacific Northwest

Date: June 11, 2026 Source: University of Washington Summary: A potentially dangerous tapeworm linked to severe, cancer-like disease has now been found in the Pacific Northwest, marking its first detection in wild animals along the U. Researchers discovered the parasite, Echinococcus multilocularis, in 37% of coyotes tested around Puget Sound—a surprisingly high rate for a region where it had never been reported until recently. Share: Facebook Twitter Pinterest LinkedIN Email FULL STORY A disease-causing tapeworm that can trigger dangerous, cancer-like cysts has been detected in Pacific Northwest coyotes for the first time. Credit: Shutterstock A dangerous tapeworm that has been spreading across North America has now been detected in the Pacific Northwest, according to new research. Scientists found the parasite, known as Echinococcus multilocularis, in local coyotes, marking the first time it has been identified in a wild host along the contiguous U. The parasite commonly infects coyotes, foxes, and other canids. While these animals often show no signs of illness, the tapeworm can cause severe disease in domestic dogs and humans if transmission occurs. For decades, E. multilocularis has been recognized as a significant public health concern across parts of Europe and Asia. In North America, however, it was once considered exceptionally rare. That changed roughly 15 years ago when infections began appearing in dogs and people in Canada and the Midwest, signaling that the parasite was expanding its range. Tapeworm Found in Pacific Northwest Coyotes Researchers from the University of Washington surveyed 100 coyotes in the Puget Sound region and discovered that 37 carried the parasite. Their findings were published in PLOS Neglected Tropical Diseases. "This parasite is concerning because it has been spreading across North America. There have been numerous cases of dogs getting sick, and a handful of people have also picked up the tapeworm," said lead author Yasmine Hentati, who recently graduated from the UW with a doctorate in environmental and forest science. "The fact that we found it here in one-third of our coyotes was surprising, because it wasn't found anywhere in the Pacific Northwest until earlier this year." When E. multilocularis infects a person or animal, it can produce cancer-like cysts in the liver and, in some cases, other organs. Without treatment, the infection can be fatal. How the Parasite Spreads Despite the danger it poses, many infected animals never become ill. The parasite relies on a complex life cycle involving several different hosts. Coyotes and other canids serve as the primary hosts for adult tapeworms.