Brazil has one of the highest rates of pet ownership in the world, in densely populated metropolitan cities; and animal waste is not cleaned up on sidewalks or in parks. The pets in Brazil were studied and found to be heavily infected with immortal pathogens and parasites, which could be transmitted to people. Women in Brazil, who are of child bearing age, are estimated to be infected with toxoplasmosis (from cats) at a rate of fifty to eighty percent. Brazil also has one of the highest rates of sexually transmitted disease in the world, and a high rate of H-pylori infection. Psittacosis was first identified in Brazil, in 1917, and spread to birds and cats worldwide, through shipments of exotic birds.

The high rates of toxoplasmosis, chlamydia trachoma, chlamydia psittacosis, and H-pylori, in humans and pets, in Brazil, explains the higher rates of microcephaly; and a high rate of blindness. Toxoplasmosis alone can cause microcephaly, or can serve as a host to the Zika virus. Any of these pathogens can attack the eye, and cause blindness. The fact Brazil is the country that was most affected by microcephaly, and has one of the highest rates of blindness in the world, is not a coincidence.