Toxoplasma gondii, a protozoan parasite, infects a third of the world's population. Working on mice, biomedical scientists report that Toxoplasma infection leads to a disruption of neurotransmitters in the brain and postulates that it triggers neurological disease in those already predisposed to such a disease. The researchers note that Toxoplasma infection leads to a significant increase in glutamate -- the primary and most important neurotransmitter in the brain.