The link between brain defects in babies and the mosquito-borne Zika virus is still a matter of debate, with some doctors proposing a possible connection with pesticide use. But the Zika argument received a boost this week, following reports that scientists in Brazil have found the virus in the brains of babies with microcephaly.

Images of infants with deformed heads puts a horrifying face on the disease, says Matthew Klingle, who points out that “Zika is one of many diseases, both vector-borne and non vector-borne, that are taking advantage of our earth’s changing climate, as well as our increased ability to travel long distances, to expand well beyond their normal range.”

Klingle, who is associate professor of history and environmental studies, has made the history of medicine and public health one of his specialities. He notes the different responses there have been to the Zika crisis in the region, from the out-and-out “war on mosquitoes” declared by the Brazilian government, to the advice issued by other Latin American countries, such as Ecuador and Colombia, urging women to postpone getting pregnant for the time being. This wide range of responses, he says, reflects how people have reacted to public health crises over the past century and a half: “You either try to eliminate the vector or you control human behavior, and I think what history shown is that you have to do a bit of both.”

Both approaches have their problems however. First, the eradication option: “Take for example DDT,” (the pesticide widely used in agriculture during the 1950’s, 60’s and 70’s.) “That did a lot of collateral damage to ecosystems and likely to human health. And while it may not eliminate all the vectors, it  can actually help breed resistance to pesticides and lead to problems further down the road.”

Regarding the second approach, Klingle says: “The challenge with trying to control human behaviors is that we’re talking about intimate and problematic areas of social policy — reproduction and women’s health. And that’s a challenge when you start to have governments telling women they cannot or should not be getting pregnant. “That,” says Klingle, “wades into some very thorny issues around contraception, around family planning.” The situation is further complicated, he says, by the strong influence in Latin America of the Roman Catholic Church, which is traditionally opposed to contraception.