When doctors found a mass the size of a grapefruit growing on her liver, Cassidy Armstrong was forced to prepare for the worst. The thirty-six-year-old from Alberta, Canada, was diagnosed with a rare type of deadly liver cancer and was given no more than a few years to live.
After undergoing surgery to remove the tumor, however, doctors were surprised to find out that what Armstrong had was not cancer at all, but a rare parasite. While still not ideal, this outcome is much preferable to her original diagnosis and has given her a renewed chance at life.
“I wasn’t sure what to think. I asked them, ‘Is this good?’ and they said, ‘It’s much better than what we thought you had,’” she said .
A New Problem in North America
The rare parasitic disease, known as alveolar echinococcus (AE), is very new to North America, according to Dr. Stan Houston, a professor of medicine at the University of Alberta. He has only treated fifteen cases in the province since 2013 .
AE comes from a tapeworm called Echinococcus multilocularis, and you can become infected if you inadvertently swallow the worm’s larvae, or eggs . There are approximately 18 235 cases reported annually around the world, with the greatest number of cases occurring in northern latitudes, particularly China [2,3].
The eggs are carried by a host, which is most commonly a fox, however, dogs are becoming increasingly common. The eggs, which are excreted in the feces of these animals, can be transferred to humans either through direct contact (ie- petting a dog that has small amounts of fecal matter on its fur) or indirectly through the contamination of food or water [3,4].
Although still rare in North America, this disease is among the world’s most dangerous zoonoses, (diseases that can be transferred from animals to humans) .
The area of the US where the tapeworm that causes the disease has been reported stretched from eastern Montanna to central Ohio, and there have been rare cases found in Alaska and Minnesota .
What is a Parasite?
A parasite is an animal or a plant that must live on or in another animal or plant in order to survive. This includes stomach or gut worms, hair and body lice, and protozoa such as Giardia. Most parasites are so small that they require a magnifying glass to be seen .
How are Parasites Treated?
The treatment for a parasitic infection depends on the type of parasite in question. For some, no treatment is needed and the infection may disappear on its own. There are, however, some antiparasitic drugs that are designed to eliminate parasites, or in the case of worms, reduce their number enough to clear up symptoms.
Evidence-based holistic remedies also exist for intestinal parasites. These include but are not limited to plants, herbs, and foods like wormwood, pumpkin & papaya seeds, and berberine.
Parasites in Humans
It can be difficult to know if you have a parasite, and because infections like these are not common in North America, doctors will often diagnose it as something else initially. Parasitic infection in humans can often behave like a tumor, which is why Armstrong was diagnosed at first with cancer.
“They’re just multiplying and spreading locally,” Houston said. “They can spread to other parts of the body like cancer can.” 
So how did Armstrong know there was something wrong? Her case started a few years ago with a vague pain on the right side of her rib cage. The pain would come and go and was not very intense, so after blood tests and x-rays came back that showed nothing out of the ordinary, she figured it was nothing to be worried about.
Armstrong began to realize something actually was wrong, when in the past year she lost twenty-five pounds, developed anemia and digestive problems, and couldn’t sleep. The pain in her ribs had also become more constant, which prompted her to request the ultrasound that revealed a giant mass on her liver .
Houston suspects that the parasite had been living inside Armstrong for ten to fifteen years, which coincides with the time in her life when she was working outside repairing farm equipment. People who live in rural areas are at a greater risk of contracting a parasitic infection because they are more likely to come into contact with an infected animal or their feces [1,4].
Take Preventative Action, But Don’t Worry
Houston says that the best way to protect yourself from a parasitic is to wash your hands, especially after petting a dog or after spending time in a garden or other location where you are exposed to a lot of mud and dirt. You should also make sure to wash your produce thoroughly if it comes from a garden that is frequented by foxes and other rodents [1,2].
As we are seeing more and more foxes and other rodents living in urban areas in close proximity to humans, Houston believes we will likely begin to see more cases of parasitic infections like Armstrong’s in the United States and Canada.
“We’re almost certainly going to see some more [human] cases, but this is still a rare disease,” he said. “People shouldn’t be getting too freaked out about it.” 
“I have mixed feelings about it. I’m happy — I like being alive,” Armstrong said. “Psychologically, it’s been really tough. I’m grateful and I’m happy that it’s not what they thought it was. But it’s been very hard.”
Doctors can’t guarantee that they removed the entire parasite, so Armstrong may have to continue taking anti-parasitic medication for the foreseeable future. This is because there is no drug available that is strong enough to destroy the parasite, only one that controls it. She will also have to have monthly blood tests and a CT scan every six months .
As someone who has always had physical jobs, she is uncertain what her next step will be, since she will no longer be able to do intense manual labor.
“It’s just scary trying to figure out: OK, what’s the next thing? What do I do now?” she said .
As the disease becomes more prevalent, it is important to ensure you are washing your hands regularly, and that you speak with a doctor immediately if you think you are showing symptoms and you think you may have been exposed to a parasite.