CDC Scientists Discover Cancer Cells in Humans can Originate in Tapeworms
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November 05, 2015

Can a tapeworm give you cancer?

A recent discovery by scientists at the Centers for Disease Control and Prevention (CDC) found cancer cells originating in a common tapeworm may take root in people with weakened immune systems, causing cancer-like tumors.

So far is there only one known case of a person becoming ill from cancer cells that arose in a parasite, but the report raises concerns that other cases may be misdiagnosed has human cancer. This is especially possible in less developed countries where this particular tapeworm – Hymenolepis nana – and immune-system-suppressing illnesses are widespread.

"We were amazed when we found this new type of disease – tapeworms growing inside a person essentially getting cancer that spreads to the person, causing tumors," study author and CDC staff pathologies Atis Muehlenbachs said in a statement.

Muehlenbacks went on to say that this type of event is rare, but with millions of people suffering from conditions like HIV there may be more cases that are unrecognized.

The findings stemmed from a 2013 case in which doctors in Colombia asked the CDC to help diagnose bizarre biopsies from lung tumors and lymph nodes of a 41-year-old man who was HIV positive. The tumors looked similar to a human cancer, but initial CDC lab studies revealed the cancer-like cells were not human. That revelation kicked off a nearly three-year hunt for the cause of the man's illness.

Dozens of tests later, researchers eventually found DNA from H. nana tapeworms in the man's tumor.

Figuring out how to help a patient who suffers from a similar ailment could be tricky for doctors – drugs to treat tapeworm infections may not be effective against tapeworm cancer cells in people. It is not clear whether human cancer treatments would help, although researchers think they might be beneficial. Physicians in developing nations should be aware of the possibility of similar illnesses, especially if they have patients with weakened immune systems who have tumors.

H. nana infects up to 75 million people at any given time, making it the most common tapeworm infection in humans. People get the tapeworm by eating food contaminated with mouse droppings or insects or by ingesting feces from someone else who is infected. Children are most often affected. Most people show no symptoms. However, in people whose immune systems are weak, including people who have HIV or are taking steroids, the tapeworm thrives.