Cat Parasite Could Hold Key to Curing Cancer for Humans

Lorie Huston, DVM
August 07, 2014
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Cats are often maligned for many different reasons. Not the least of these reasons is the threat of toxoplasmosis, a disease caused by an organism known as Toxoplasma gondii. Though Toxoplasma can infect many different types of animals, the cat is its natural host. T. gondii makes its home in the intestinal tract of the domestic cat.

Toxoplasmosis is a very real disease and I don’t want to make light of it. It can be especially dangerous for pregnant women and the fetuses they carry. It can also be dangerous for individuals that are immunocompromised.

In addition to these known dangers, T. gondii has also been implicated in causing a variety of other problems, ranging from suicidal tendencies to an increase in the risk of brain cancer. Though these allegations are tenuous at best, they are nevertheless often reported in the popular press. T. gondii has also been implicated as a cause of deaths in sea lions, seals, sea otters, whales, and dolphins, a link that worries many biologists, ecologists, and others.

All of these factors have, in some instances, led to a backlash directed at cats, particularly at the many feral (or community) cat populations. Recently, however, T. gondii is being cast in a different light.

In research currently being performed by David J. Bzik, PhD, a professor of microbiology and immunology and Barbara Fox, a senior research associate of microbiology and immunology at the Geisel School of Medicine at Dartmouth, T. gondii is being investigated as a potential treatment for cancer patients.

Says Dr. Bzik in a quote on the Geisel News Center webpage, “biologically this parasite has figured out how to stimulate the exact immune responses you want to fight cancer.”

Most cancer patients, as a result of their disease, suffer some degree of immunosuppression, making them less than ideal candidates for infection with the unaltered toxoplasmosis organism. To overcome this stumbling block, Bzik and Fox have created a mutated form of the parasite, effectively removing a gene and making it impossible for the mutated organism to reproduce in people or in animals.  

Known as “cps,” the mutated form is safe, even for immunosuppressed individuals, because it cannot reproduce but it can still be used to “reprogram the natural power of the immune system to clear tumor cells and cancer.”

Though the research results obtained thus far are promising, both Bzik and Fox caution that further research is still needed. They foresee the potential, though, for developing a product that could be individualized tailored for each patient and the specific form of cancer being treated for that patient.

Should this research prove successful, a significant break-through in our ability to treat various forms of cancer would be the result. Ultimately, this research could benefit both people and pets, resulting in a treatment for some types of cancer that are currently not very easily or successfully handled.

Dr. Lorie Huston

Image: Annmarie Young / Shutterstock