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A rare parasite that causes cancerous growths in the liver of humans has become increasingly common in North America, especially in certain parts of Canada, over the past decade.
As reported in the American Journal of Tropical Medicine and Hygiene, a team from the University of Alberta argues that the province of Alberta in western Canada has become a North American hotspot for the rare infection known as human alveolar echinococcosis (AE). Prior to 2013, only two human cases of the parasitic infection had been confirmed in all of North America. However, in the new study, the researcher identified 17 cases in Alberta between 2013 and 2020.
The researchers believe the AE strain was likely brought to Canada by dogs from Europe, where the disease is rare but well-established, before it was transmitted to urbanized coyotes and humans.
“Coyotes in Calgary and Edmonton have been found to be more than half carrying this parasite. So not only does the new strain appear to be more virulent when attacking humans, but it also appears to be super effective on wild hosts.” Stan Houston, an infectious disease expert from the University of Alberta who led the study, said in a statement.
The tapeworm-like parasite called Echinococcus multilocularis lives harmlessly in its typical life cycle in the small intestine of dogs, typically foxes and coyotes, but also domestic dogs. When the parasite’s eggs are puked up and eaten by rodents, the disease lasts for disease another form and leads to cyst-like tumors in the liver, which the animal eventually kills.
If humans ingest the eggs of the parasites, they too can suffer this evil fate. According to the Centers for Disease Control and Prevention, People with the infection can also have tumors in the Liver and lungs and less often in bones, kidneys, spleen, muscles and the central nervous system. However, the disease is relatively difficult to detect in humans because it can easily resemble other diseases, especially cancer. The symptoms are also pretty vague, such as: unspecified pain, jaundice, weakness, and weight loss.
The parasite can kill a human host within 10 to 15 years if left untreated. If the infection is detected early, surgery to remove the liver mass is possible, although two-thirds of patients become inoperable because they do not get a diagnosis quickly enough. In these patients, lifelong treatment with antiparasitic drugs can help stop the growth of the mass, but the parasite will survive.
Of the 17 cases documented in this study, 11 patients lived in rural areas, 14 of them had dogs, and six had compromised immune systems. In almost half of the cases, patients were only diagnosed with the parasitic infection while being tested for another disease.
“In most cases, when people first saw the imaging, the first thing they thought was cancer,” Houston said. “The symptoms would be indistinguishable from many other liver diseases, so a biopsy diagnosis is required.”
To prevent this nasty infection, Houston advises people to take some simple hygiene precautions, such as thoroughly washing fruits and vegetables that were on the floor. If you own pets, wash your hands as often as possible after touching them, especially if they have come into contact with a rodent or an area where coyotes are hanging out.
“We should be careful, but it is still a very rare disease,” he added. “People should keep this in mind, adopt health behaviors and not be obsessed with them.”
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