Cases of a rare parasitic disease commonly found in canines have significantly increased in North America, especially in Alberta, Canada.
A fatal parasitic disease is on the rise across Europe and Asia. Although cases are extremely rare in North America, researchers argue that the incidence is increasing, specifically in Alberta, Canada. Recently, a team of researchers at the University of Alberta conducted a review of known cases of the disease in the province. They reported their findings in the American Journal of Tropical Medicine and Hygiene.
The parasitic disease, called human alveolar echinococcosis (AE) was once only found in a remote Alaskan Island. Prior to 2013, only two cases of the disease existed in North America. However, the new study identified a total of 17 cases between 2013 and 2020 in Alberta. According to study authors, this strain of human AE originated from Europe and likely came to Alberta through dogs.
In coyotes in Calgary and in Edmonton, more than half have been found to be carrying this parasite. So the new strain seems to not only be more virulent when it affects humans, but it seems to be super-effective in wild hosts
Stan Houston, study author
Out of the 17 reported cases, 14 had pet dogs and 6 suffered from varying degree of immunosuppression. Their ages ranged in between 19 to 78 years. For most of the cases, the disease was an accidental finding; discovered while undergoing surgery or imaging for another illness.
What is Human Alveolar Echinococcosis?
Human AE is a parasitic disease caused by the tapeworm Echinococcus multilocularis. The tapeworm commonly exists in canines such as foxes, coyotes, and pet dogs. However, the parasite is harmless in them. Rodents can ingest the parasites’ eggs present in canine feces and develop tumor-like lesions in the liver. Similarly, humans can also become infected by consumption of food contaminated with feces from coyotes or dogs. Additionally, petting dogs with traces of feces on their fur can also infect humans.
Unlike rodents, humans can also develop tumor-like lesions in the bones, lungs, kidneys, and the brain. However, the lesion is difficult to diagnose. The long incubation period of 5-15 years means people can stay asymptomatic for years. Moreover, it often resembles cancer on imaging and the symptoms can mimic a liver cancer. People commonly present with weight loss, abdominal pain, weakness, and jaundice.
In the majority of cases that was the people’s first thought when they saw the imaging, that it was cancer. The symptoms would be indistinguishable from many other diseases in the liver, hence the need for a biopsy diagnosis.
Stan Houston, study author
Due to the long incubation period, the disease can grow and infect other parts of the body. Typically, treatment involves surgical removal of the liver mass, but the mass can become inoperable in some. A lifelong treatment with antiparasitic is then prescribed. Moreover, if urgent treatment is not sought, the parasite can cause death within 10 to 15 years.
Therefore, researchers advise practicing good hygiene and proper washing of produce. They further suggest that human AE should be a possible diagnosis in patients presenting with nonmalignant liver mass.
Reference:
Houston, Stan, et al. “Epidemiological and Clinical Characteristics of Alveolar Echinococcosis: An Emerging Infectious Disease in Alberta, Canada.” The American Journal of Tropical Medicine and Hygiene, 2021, doi:10.4269/ajtmh.20-1577.
