In 2014, the Brazilian government added pyriproxyfen, a toxic larvicide used to control mosquito populations, to water tanks throughout the country. A new report from a group of Argentinian physicians claims the toxic substance, rather than the Zika virus, is to blame for the huge spike in babies born with microcephaly in Brazil, although the Brazilian government has dismissed the claims, according to The Telegraph.
The Argentinian report claims past outbreaks of Zika virus have not been accompanied by spikes in birth defects, and the areas with the highest use of pyriproxyfen are the ones experiencing the greatest concentrations of microcephaly, which has been associated with Zika virus, although no absolute scientific evidence has proven the link. The larvicide manufacturer, Sumitomo Chemical, which is associated with Monsanto, claims the substance poses minimal risk to mammals.
A January report from The Washington Post pointed out that a significant number of microcephaly cases related to the Brazilian uptick are not Zika-related, suggesting an underlying factor may be at play. Of the approximately 4,000 cases of microcephaly reported in Brazil, experts reviewed 732 and found more than half were either not Zika-related, or not microcephaly, according to The Washington Post.
The Colombian national health institute announced Sunday that more than 5,000 pregnant women in the country are believed to have Zika, with 31,555 cases of the virus reported overall. In early February, Colombia's President Juan Manuel Santos said there's no evidence Zika had been linked to any instances of microcephaly in the country, according to ABC News.
Amidst questions about what is causing the spike in microcephaly, the Brazilian government launched a national "Zika Zero" campaign, which entailed nearly 250,000 military personnel flyering the streets about how to combat the virus by reducing mosquito breeding grounds, according to The New York Times.