Larvicide to Blame for Microcephaly Cases, Group Claims – Is it True?

(Photo: AP Images)

A group of physicians in Argentina are challenging the notion that a dramatic increase in newborn brain damage in Brazil is linked to the Zika virus. Instead, they claim it’s due to a larvicide added to Brazil’s water supply.

The group, Physicians in Crop-Sprayed Towns (PCST), says a chemical larvicide called pyriproxyfen was added to Brazil’s water supplies in 2014 in order to stop the development of mosquito larvae in drinking water tanks. The organization alleges that pyriproxyfen, not Zika virus, is to blame for the rise in cases of infants born in Brazil with unusually small heads, a condition known as microcephaly.

Nearly 4,000 babies in Brazil have been born with microcephaly since October. By contrast, Brazil reported fewer than 150 cases of microcephaly in 2014.

Scientists freely admit that they’re still learning about Zika virus and its side effects. Could this be true?

Board-certified infectious disease specialist Amesh A. Adalja, MD, an assistant professor at the University of Pittsburgh Medical Center, tells Yahoo Health that he’s doubtful. “I don’t think this is the cause for microcephaly because the levels consumed in the drinking water are much lower (300 times) than the WHO limits,” he says.

Not only that, Adalja says we would have seen these cases before since pyriproxyfen has been used in water supplies in the past. “We would have seen cases years ago as the use of pyriproxyfen increased,” he says.

Zika is spreading throughout South America and Central America and the Caribbean, and the World Health Organization (WHO) recently predicted that the virus will spread to all but two countries in South America, Central America, and North America (including the United States by late spring or early summer).

Because of the virus’s link with microcephaly (and, more recently, eye damage in newborns), officials in Brazil, Colombia, El Salvador, Ecuador, and Jamaica are urging women to delay having children.

In response to the new allegations, government officials in Rio Grande do Sul, a state in the south of Brazil, stopped the use of pyriproxyfen in its water on Saturday.

“We decided to suspend the use of the product in drinking water until we have a position from the Ministry of Health, and so, we reinforce further still the appeal to the population to eliminate any possible mosquito breeding site,” Joao Gabbardo dos Reis, state health secretary in Rio Grande do Sul, told the U.K.’s The Telegraph.

But the Brazilian government says the new claims are unfounded. “Unlike the relationship between the Zika virus and microcephaly, which has had its confirmation shown in tests that indicated the presence of the virus in samples of blood, tissue and amniotic fluid, the association between the use of pyriproxyfen and microcephaly has no scientific basis,” government officials said in a statement. “It’s important to state that some localities that do not use pyriproxyfen also had reported cases of microcephaly.”

Monsanto also denies the link. In a statement on their website, the company refers to the allegations as “misinformation and rumors.” “Neither Monsanto nor our products have any connection to the Zika virus or microcephaly,” the statement reads.

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Questions abound about the Zika virus

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