When you feel a weird pain in your leg, you might assume that you slept on it funny or went a little too hard on your morning run. What you don't expect is to be told your pain is due to a parasite lodged in your back. Unfortunately, that's exactly what happened to a woman in rural France. Luckily, her story, detailed in a recent case report published last month in the New England Journal of Medicine, is highly unusual.
According to the report, the woman, 35, went to the ER and said that she had been having trouble riding her horse for three months. She had been experiencing weakness, falls, and experiencing "electric shocks" in both of her legs, and she said her symptoms were only getting worse. Doctors conducted a slew of tests to try to figure out what was going on, and it was only after she had an MRI of her spine that they found a lesion on her ninth thoracic vertebra (around the middle of her spine). After testing it, they discovered the lump was caused by a parasitic tapeworm, Echinococcus granulosus.
The woman had surgery to remove the tapeworm and was treated with the antiparasitic medication albendazole, the case report says. At a nine-month follow-up, she didn't have any residual symptoms.
Echinococcus granulosus is actually a pretty common parasite, but it’s unusual for it to show up in a developed country.
Echinococcus worms, which are tiny tapeworms, can cause an illness called echinococcosis. The illness comes in two forms: cystic echinococcosis (which is what the woman in the case report had) and alveolar echinococcosis (which can cause parasitic tumors to form in the brain, liver, lungs, and other organs), according to the Centers for Disease Control and Prevention (CDC).
In most cases, the diseases are transferred to humans by animals, usually dogs. When dogs eat the organs of other animals that contain the tapeworms, the CDC explains, the dogs shed the tapeworms in their poop, which contaminates the ground. The most common way people get these tapeworms is by accidentally eating dirt, water, or food that’s been contaminated by infected dog poop, according to the CDC.
More than one million people are infected with these tapeworms at any given time around the world, according to the World Health Organization (WHO), but it’s more common in countries like Argentina, Peru, and China. “It’s not something that you see routinely in the U.S.,” Amesh A. Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security, tells SELF. “Most infectious disease doctors in the U.S. probably haven’t seen these here," he says, unless they’re taking care of someone who has recently been to a country where the tapeworms are more common.
Once the parasite gets in you, it tends to head for your liver or lungs, according to the WHO.
Once it reaches your lungs or liver, it forms what are known as hydatid cysts. These cysts can also show up in your bones, kidneys, spleen, muscles, central nervous system, and eyes, the WHO says, but that's less common.
The symptoms are about as fun as you’d expect if you’re growing a tapeworm inside you. They include stomach pain, nausea, and vomiting when it’s in your liver, and a chronic cough, chest pain, and shortness of breath when it’s in the lungs, according to the WHO. Other symptoms depend on where the cyst forms as well as the tissues around it, which explains why this woman had back pain and electric jolts in her leg after it formed on her spine, Dr. Adalja says.
You can have echinococcus worms in your body for years until the cysts grow to a point where you would develop symptoms, according to the WHO. But about half of patients that receive treatment for an echinococcus illness do so within a few years of being infected. The parasite is usually picked up by CT scan or MRI and treatment generally involves surgery and antiparasitic medication, the WHO says.
Remember that this is super rare in the U.S., so if you're ever in pain, you don't need to assume it's related to a parasite.
The researchers point out in the case report that the woman had “no history of foreign travel,” but that she did own a cat and “had contact with cattle.” So, it’s likely she picked it up from an animal.
But even if you live on a farm, you shouldn’t freak out. “These case reports get attention because they’re medical oddities and so unique,” Dr. Adalja says. “This is not something the average person in the U.S. needs to worry about.”