Here’s another reason to cook your meat and take care of cat litter: the parasite Toxoplasma gondii, which reproduce in cats and spreads mostly through raw meat to humans, may increase the risk of brain cancer in humans, a new study indicates.
The researchers found a link between the presence of T. gondii antibodies in human blood, indicating previous exposure to the parasite, and the development of glioma, the most common type brain cancer, several years later.
The findings, released Monday (January 11) in the International Journal of Cancer, “suggests that individuals with a higher exposure to the T. gondii parasite is more likely to develop glioma, “studied co-author Anna Coghill, a cancer epidemiologist at the Moffitt Cancer Center in Tampa, Florida, said in a statement. However, Coghill warned that current findings ‘should be repeated in a larger and more diverse group of individuals’ and that the average person’s overall risk of developing glioma during their lifetime remains low.
In addition, the present study cannot prove a cause-and-effect relationship. ‘It does not mean it T. gondii certainly causes glioma in all situations, “co-author James Hodge, an epidemiologist at the American Cancer Society in Atlanta, said in the statement. Some people with glioma have no T. gondii antibodies, and vice versa. ”
Related: 7 strange facts about the ‘mind-control’ parasite Toxoplasma gondii
Brain parasite
T. gondii infects most warm-blooded animals, including humans. However, it only undergoes sexual replication in cats, so it must infect them to complete its life cycle. The parasite, which can infect the brain, is known for it which makes infected rodents less careful for cats and the facilitation of own reproduction. It is also associated with behaviors that take risks in humans. Although humans can be exposed to the parasite by removing cat litter from an infected pet, a more common route of exposure is by ingesting raw or overcooked meat from an infected animal.
T. gondii infections, known as toxoplasmosis, is common, affecting an estimated 2 billion people worldwide and 40 million in the United States, Live Science reported earlier. Most people with the infection have no symptoms because their immune systems keep the parasite in check, but in rare cases, the parasite can cause severe symptoms, including vision loss, according to the Centers for Disease Control and Prevention (CDC).
Glioma is a deadly cancer, and glioblastoma is the deadliest subtype. The estimated five-year survival rate of glioblastoma is only 6% in people 55 years and older, compared to the general population who do not have cancer, according to the American Cancer Society. Risk factors for glioma include being male, non-Hispanic white, older and taller.
To the influence of T. gondii exposure to the risk of developing glioma, the researchers looked for antibodies against T. gondii in blood samples from people who had glioma (the samples were collected several years before their diagnosis) as well as a cancer-free control group. The researchers used blood samples and data from participants in two previous studies: the American Cancer Society’s Cancer Prevention Study-II Nutrition Cohort (CPSII-NC) and the Norwegian Cancer Registry’s Janus Serum Bank (Janus).
Participants with glioma were more likely than antibodies to participants in the control group T. gondii in their blood samples, the researchers found. In addition, participants in the Janus study increased the risk of glioblastoma with T. gondii antibody levels, meaning that the higher their antibody levels, the greater their risk, the researchers found. The connection between T. gondii exposure and glioma risk were not statistically significant for each individual antibody tested and for each glioma subtype.
This was the first prospective study – this is one that has been investigated T. gondii exposure to cancer diagnosis – to establish a link between T. gondii exposure and glioma development, the authors wrote. This study design enabled the researchers to avoid the possibility that a glioma parasite linkage was actually due to gliomas that increase the risk of infection with the parasite.
The identification of T. gondii as a risk factor for glioma can have practical implications. Although most risk factors for glioma are not changeable, exposure to parasites is something people can try to avoid, the authors said.
If other studies confirm these findings, “reducing exposure to this common food-borne pathogen would provide the first tangible opportunity to prevent this extremely aggressive brain tumor,” they concluded.
Geoff Hide, a parasitologist at the University of Salford in the UK, agrees that ‘in principle reduces T. gondii exposure is likely to prevent some gliomas – probably because the immune system is less stressed. ‘Hide was not involved in the current study, but he co-authored a 2019 study in the journal. ERJ Open Research a connection between the presence of T. gondii antibodies and lung cancer.
“This study suggests a link between exposure to Toxoplasma gondii and increased glioma risk, “Dr. Craig Horbinski, a neuropathologist at the Feinberg School of Medicine at Northwestern University in Chicago, emailed WordsSideKick. If the connection is real, preventing such exposure can reduce the risk of preventing this usually fatal. cancers. “
But both Horbinski, who was not involved in the research, and the authors of the study believe more data are needed to determine whether the link between parasite exposure and glioma development is valid. “The data are interesting, but not sufficient to draw any firm conclusions,” Horbinski said.
In the future, researchers should do more studies on larger populations that include more cases of glioma, Horbinski said. “This is the only way to resolve this controversy,” he added.
Originally published on Live Science.