Echinococcus species in North America: an increasing concern for domestic animals, wildlife, and humans.

Echinococcus multilocularis and Echinococcus canadensis (genotypes G8 and G10) are emerging parasites of concern across North America. Historically confined to northern and western regions, both species have been detected with increasing frequency in new geographic areas in wildlife, domestic dogs, and humans. Both Echinococcus spp have indirect life cycles involving carnivore definitive hosts (domestic and wild canids) and either herbivore intermediate hosts (for E canadensis) or rodents (for E multilocularis). For E multilocularis, domestic dogs can serve as both definitive hosts, shedding eggs into the environment, and aberrant intermediate hosts that can develop severe, often fatal alveolar echinococcosis (AE). Clinical presentations in dogs with AE include hepatic masses, abdominal distension, anorexia, and hematological abnormalities. Intestinal Echinococcus spp infections in canids can be treated with products that contain praziquantel, but treatment of canine AE cases is complicated and has a poor prognosis. Intestinal infections can be diagnosed by fecal examinations and detection of eggs; however, importantly, the eggs are morphologically indistinguishable from Taenia spp. Molecular testing is therefore essential to definitively determine the parasite species. Given expanding parasite ranges, the close human-dog bond, and the severity of disease in both dogs and people, enhanced surveillance programs and routine veterinary testing and treatment protocols are important to minimize the risk of infection. Because diagnosis is important to prevent infection, the companion Currents in One Health by Garrett et al, AJVR, July 2026, investigates different methods of detection using fecal testing.