BRASILIA, Brazil, Feb. 15 (UPI) -- The Brazilian government is denying a report by an Argentine doctor group linking rises in the microcephaly birth defect not to the Zika virus but to a larvicide, a report which caused a Brazilian state to suspend the chemical agent's use.
The Physicians in the Crop-Sprayed Towns organization suggests pyriproxyfen, a larvicide used to control the Aedes Aegypti mosquito, could be the cause of the sharp increase in microcephaly, a developmental defect resulting in a smaller-than-normal head or brain in newborns.
The group said pyriproxyfen was introduced to Brazil's drinking water in 2014 in regions affected by the microcephaly increase.
"In the area where most sick persons live, a chemical larvicide producing malformations in mosquitoes has been applied for 18 months, and that this poison [pyroproxifen] is applied by the state on drinking water used by the affected population," a report says.
Brazil's Rio Grande do Sul state responded by suspending the use of pyroproxifen on Saturday "until we have a position from the ministry of health," but adding that it continues to advocate for the Brazilian "population to eliminate any possible mosquito breeding site."
Brazil's federal government said there was no scientific evidence to link pyriproxyfen to microcephaly. At least 41 cases may be linked to the Zika virus in Brazil out of 462 confirmed cases of the birth defect.
"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," the government said in a statement. "It's important to state that some localities that do not use pyriproxyfen also had reported cases of microcephaly."
Hospitalizations and fatalities due to Zika infection are rare, with symptoms such as rash and fever lasting from a few days to one week. The virus was first isolated from a monkey in Uganda's Zika forest in 1947.