Researchers at the Center for Disease Control and Prevention have identified a puzzling and unsettling new cancer-like illness in a 41-year-old man. The patient is believed to have been infected through a common stomach bug.
The findings were published on Wednesday in the New England Journal of Medicine.
This is the first known transmission of cancer cells from a parasite to a human. This case involves an HIV patient from Columbia who developed multiple large tumors in various parts of his body.
Local doctors biopsied the tumors and found that the cells acted like cancer cells in their destructiveness, however they were strange in other respects. They were about 10 times smaller than normal human cancer cells. The doctors contacted the Center for Disease Control and Prevention for help.
Researchers weren’t sure what to make of the cell samples when they were received in 2013.
The cells’ growth pattern was cancer-like, with overcrowding and a high rate of multiplication. But the cells were also fused together, which is rare for human cells.
An earlier theory was that they could be a new type of infectious organism. However after numerous tests, researchers discovered that the cells contained DNA snippets of a dwarf tapeworm. The analysis was verified by a researcher and tapeworm expert at the Natural History Museum in London.
Researchers believe that the patient ingested microscopic tapeworm eggs, most likely in food contaminated by mouse droppings, insects or human feces.
Due to the man’s compromised immune system, the tapeworms were able to quickly multiply inside his gastrointestinal tract and the cells invaded other parts of his body. It is unclear whether the cell sin the tapeworm eggs exhibited cancer like properties before they entered his body or whether some interactions between the parasite and his body caused them to be cancerous.
This is the first instance of parasite-derived cancer cells spreading within an individual. The case study is worrisome. Until now, researchers did not believe that any human parasite could harbor cancer cells or transfer them to people.
Further investigation is necessary to determine whether this ability to transfer cancer-like cells is limited to tapeworms or if there is some underlying biological phenomena that might lead to transmissible cancer cells developing in other creatures that can pass them along to humans.