A staggering 30-50% of the world's population is estimated to be infected with the parasite Toxoplasma gondii. This parasite is known to invade the brain and affect behaviors
Toxoplasma gondii, also known colloquially as "Toxo," can infect virtually any warm-blooded animal. However, the parasite can only undergo sexual reproduction in domesticated cats, and so most people know Toxo as the disease that humans can get from changing and accidentally ingesting contaminated cat litter.
Toxoplasmosis, the disease caused by Toxo, can be life threatening for people with compromised immune systems, such as infants, cancer patients, or HIV/AIDS patients. In addition, pregnant women can transmit the parasite to their unborn baby. Toxo invasion of the brain has been linked to adverse behavioral changes, and has been implicated in psychiatric diseases like schizophrenia. Although the precise mechanism of how the parasite invades the brain is still under active investigation, a team at Penn captured Toxo invasion in the brain through the endothelial cells, which make up the lining of blood vessels. The mechanisms behind Toxo's invasion may also illuminate how other pathogens breach our defense to the brain.