Wendy Ingram

Joint Graduate Student with Ellen Robey

Wendy Ingram

Brain Pathlology and Behavioral Manipulation in the Mouse Intermediate Host During Chronic Toxoplasma gondii infection. 

Toxoplasma gondii is an obligate intracellular single celled parasite that infects warm-blooded vertebrates. Infection can occur carnivorously, congenitally, and by consuming oocysts shed by cats in their fecal matter. Felines are considered the parasite’s primary host since the feline gut is the only known location of sexual reproduction and results in the distribution of millions of infectious oocysts. Felines are susceptible to infection primarily via carnivorism of a chronically infected intermediate host. When intermediate hosts such as mice are acutely infected, the parasite transitions to the tachyzoite phase where it invades any cell, rapidly proliferates and moves to most tissues in the body. As the immune system of the host begins to control the infection, the parasite will make its way to the brain and differentiate into a slow-growing bradyzoite form that establishes cysts inside intact cells. These cysts will then persist during the entire life of the host. It is proposed that T. gondii has the unique ability to behaviorally manipulate its intermediate host to increase its chances of being consumed by its primary host, the cat. Mounting evidence supports the notion that chronic T. gondii infection, under low brain pathology conditions, specifically ablates and possibly reverses the natural aversion of cats in rodents.