Toxoplasma gondii is a widespread intracellular animal parasite, and one of the most widespread zoonotic pathogens in the world, infecting one-third of the population. Toxoplasmosis can cause brain and central nervous system disease, lung disease, cancer (including brain cancer), and skin disease; and has been “associated” with Alzheimer’s disease, demyelinating diseases, autoimmune disease, movement disorders, and epilepsy. Toxoplasmosis can cross the placenta to cause microcephaly and other birth defects; development of seizures, in infants; and regressive developmental disorders, in children.

Toxoplasmosis can migrate to abdominal organs, and cause disease in the liver and pancreas; and has been “associated” with obesity. Toxoplasmosis can migrate from the stomach to the brain and eye, along the vagus nerve; or from gastrointestinal reflux into the sinus and from the sinus to the eyes and brain. Toxoplasmosis can cause a blinding retinal disease; and in Brazil, where the T. gondii is highly diverse, with a higher average virulence as compared to the Northern Hemisphere, ocular toxoplasmosis occurs at a five times higher rate.

Acute toxoplasmosis can become chronic toxoplasmosis, and insidiously persist and proliferate, to cause systemic disease and mental illness, months or years after an acute infection. Toxoplasmosis can also harbor other pathogens, and carry the pathogens to locations reached by toxoplasmosis.

“Human impact on the diversity and virulence of the ubiquitous zoonotic parasite Toxoplasma gondii” https://www.pnas.org/content/115/29/E6956

European Multicentre Study on Congenital Toxoplasmosis (EMSCOT) Ocular sequelae of congenital toxoplasmosis in Brazil compared with Europe. https://www.ncbi.nlm.nih.gov/pubmed/18698419