A single-celled parasite called Toxoplasma gondi (T gondi), which can be found inside the intestines of cats, could prove to be a new cure for cancer, according to scientists from the Geisel School of Medicine at Dartmouth in the US.

The T gondi is generally found in the intestines of a cat, but it can (and has been known) survive inside other warm blooded animals too. However, with this new discovery, this parasite could be used for a completely new purpose altogether.

This parasite, said to have affected one third of the world's population, lives unnoticed by the host, most of them not even showing any symptoms of carrying T gondi. There are people who have been diagnosed with an illness, not unlike flu. However, if a person's immune system is not particularly strong, they could form severe infections in the body.

However, this parasite could do its real magic in the body of people with a healthy immune system, says scientists.

"We know biologically this parasite has figured out how to stimulate the exact immune response you need to fight cancer," said David J Bzik, Professor of Immunology and Microbiology at the Geisel School of Medicine at Dartmouth.

When the human body's immune system detects the T gondi inside, the former immediately releases some cytotoxic cells and some killer cells. These cells go on and fight off the cancer cells.

What cancer normally does is that it shuts down the immune system of the body. However, when the T gondi is introduced into the tumor infected region, it kick-starts the immune response, taking necessary action to fight the deadly disease.

"The biology of this organism is inherently different from other microbe based immunotherapeutic strategies that typically just tickle immune cells from the outside," said Barbara Fox, who is a senior associate of Immunology and Microbiology.

However, injecting a live cancer patient with T gondi could do more harm than good. Thus, Bzik and Fox developed an immunotherapeutic vaccine, called "cps." The researchers had to minutely study the biochemical pathways of the T gondi parasite, and replicate it. They developed a mutated form of this parasite in the lab, by deleting the Toxoplasma gene in it.

"Aggressive cancers too often seem like fast moving train wrecks," said Bzik. "Cps is the microscopic, but super strong hero that catches the wayward trains, halts their progression, and shrinks them until they disappear."