Toxoplasmose Linked to Higher Incidence of Adult Brain Cancers

[Gert van der Hoek]

Incidence of adult brain cancers is higher in countries where the protozoan parasite Toxoplasma gondii is common

Abstract

We explored associations between the common protozoan parasite Toxoplasma gondii and brain cancers in human populations.

We predicted that T. gondii could increase the risk of brain cancer because it is a long-lived parasite that encysts in the brain, where it provokes inflammation and inhibits apoptosis. We used a medical geography approach based on the national incidence of brain cancers and seroprevalence of T. gondii. We corrected reports of incidence for national gross domestic product because wealth probably increases the ability to detect cancer.

We also included gender, cell phone use and latitude as variables in our initial models. Prevalence of T. gondii explained 19 per cent of the residual variance in brain cancer incidence after controlling for the positive effects of gross domestic product and latitude among nations. Infection with T. gondii was associated with a 1.8-fold increase in the risk of brain cancers across the range of T. gondii prevalence in our dataset (4?67%).

These results, though correlational, suggest that T. gondii should be investigated further as a possible oncogenic pathogen of humans.

Biology Letters

Toxoplasma gondii
Humans can become infected with T. gondii, either through contact with soil contaminated by cat faeces, or by eating infected meat. These infections are extremely common, and up a third of the world may carry the parasite. However, rates of infection vary greatly from country to country, from just 7% in the UK and 11% in the USA, to around 67% in Brazil.

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