Comments

It's not so much that "an insecticide causes a virus" as much as an insecticide can weaken someone's immune system and a virus can tip the balance and proliferate. For example, it's been well documented that exposing a group to a virus will not lead to 100% illness of the group even with a 100% infection rate. Why is this? What is different about a sick person and a healthy one, even though both are infected with the virus? The primary difference is that the sick one's immune system couldn't keep the virus in check and the healthy person's could. DDT, like all organochlorine and organophosphate pesticides, disrupts the central nervous system (CNS). (http://www.popsci.com/environment/article/2008-03/parkinson-linked-pesticides) The immune system is heavily regulated by the CNS. So it is plausible that polio outbreaks could correlate to DDT based parasite eradication programs. The mode of action is still not well understood, but more and more research is making links between synthetic molecules like DDT and diseases of the central nervous system.