Risk for Alveolar Echinococcosis in Dog Owners
Radford G. Davis, DVM, MPH, DACVPM, Iowa State University
In the literature
Schmidberger J, Uhlenbruck J, Schlingeloff P, et al. Dog ownership and risk for alveolar echinococcosis, Germany. Emerg Infect Dis. 2022;28(8):1597-1605. doi:10.3201/eid2808.212514
The Research …
Echinococcus multilocularis is a zoonotic tapeworm predominantly found in the Northern Hemisphere that causes alveolar echinococcosis (AE), a serious disease in humans primarily treated with invasive surgery.1 AE in humans is highly prevalent in China (≈90% of global burden) and of notable concern in Europe.1,2 E multilocularis is less common in North America (documented in wildlife in ≈14 US states and 4 Canadian provinces), but its range is expanding in the central United States and Canada.2
E multilocularis is maintained in a predator–prey cycle in which the definitive host (ie, dogs, wild canids [typically foxes], cats [rare]) excretes eggs after consuming infected small mammals.1,2 Humans can then be infected via ingestion of the eggs, potentially through contaminated soil, food, water, fomites, or close contact with definitive hosts.1-3 Previous studies demonstrated an association between ownership of or contact with dogs and AE in humans.4-7
This case-controlled study in Germany conducted a written survey of dog owners with (n = 43) and without (n = 214) AE to further explore potential risk factors for AE in dog owners. No difference was found between the groups when duration of ownership and regular contact with dogs were examined. Never testing a dog’s feces for parasites and reduced deworming frequency were not risk factors for AE. Although risk for AE increased 7-fold in owners who never cleaned their dog’s coat compared with those who cleaned daily, this difference was not significant. There was also a nonsignificant increase in risk in owners in rural communities (likely due to proximity to wildlife reservoirs) and owners of dogs that ate carrion or rodents.
Risk for AE was 7-fold higher in owners with herding dogs or dogs that roamed unattended in fields. Increased risk was 13-fold in owners of dogs that consumed organic waste from other animals daily. There was a 4-fold increase in risk in owners who only sought veterinary care when their dog was ill compared with those who sought care more than once per year. Owners who did not receive information from their clinician regarding risk for and prevention of E multilocularis infection had a 10-fold increased risk.
… The Takeaways
Key pearls to put into practice:
Clinicians can help reduce E multilocularis infection by educating dog owners about the parasite, including risk factors for infection and transmission, as well as preventive measures.
Owners should not allow dogs to roam fields unattended, roll in feces of other animals, or eat carrion or prey.
One study found that monthly treatment of dogs in hyperendemic areas with praziquantel can reduce both E multilocularis shedding in dogs and prevalence of E multilocularis in intermediate wildlife hosts.8