Toxoplasma gondii is a protozoan parasite capable of infecting any warm-blooded species and can increase risk-taking in intermediate hosts.
Infection
Infection spreads either through the ingestion of oocysts shed in the environment by a definitive host (e.g., environmentally mediated transmission via water or vegetation), the ingestion of infected tissue cysts in definitive or intermediate hosts or, if the fetus survives infection, vertically through congenital transmission.
Progression
Once an intermediate host is exposed, the infection spreads from the intestinal lining to form cysts in the brain and muscle tissue and acute toxoplasmosis occurs.
Risk taking increase
Infected rodents show a reduction in their innate aversion to cat odors.
Gering et al. (2021) found that toxoplasmosis was associated with increased boldness in hyena (Crocuta crocuta) cubs and that seropositive hyenas of all ages were more likely to be killed by African lions (Panthera leo)
Here we found that T. gondii infection in wolves was predicted by pack overlap with a definitive host, cougars, and that wolves seropositive for T. gondii changed their behaviour to take greater risks—being more likely to disperse and to become pack leaders than seronegative wolves. Due to a wolf pack’s social structure, these behaviour changes may cause a feedback loop that leads to pack-level increases in risk-taking with important implications for further disease transmission, interspecific competition with cougars, and wolf survival.