Three rounds of aerial larvicide operations underscore health officials’ preventive strategy in mosquito-prone wetlands

From June to August, New Yorkers witnessed something unusual in their skies: helicopters flying low over wetlands in the Bronx, Brooklyn, Queens, and Staten Island, dispersing biological larvicides. The city’s Department of Health carried out the flights as part of a campaign to prevent the spread of West Nile virus—a disease that has haunted American summers for decades.

But this time, the story also found its way onto the website of Brazil’s National Agricultural Aviation Association (SINDAG). The group echoed New York’s official reports on the 2025 operations to call Brazilian policymakers’ attention to the effectiveness of this technique. It was also an attempt to challenge the stigma that has long plagued the country’s aerial application sector.

To this end, the text also replicated the link to guidelines from the US Centers for Disease Control and Prevention (CDC), explaining the safety of air operations to protect the population.

The stigma contrasts with international practice, as aerial mosquito control has proven effective for decades in many parts of the world, including Brazil itself. Scientific records point to a 1975 case in the state of São Paulo, where two planes helped eradicate an outbreak of encephalitis caused by Culex mosquitoes in three cities.

DISPARITY

Brazil’s legal framework has recognized aerial control for decades. Since the 1960s, national regulations have allowed mosquito control flights, and in 2013, a federal law on combating epidemics explicitly authorized the use of aircraft to apply insecticides and larvicides. The measure was later upheld by Brazil’s Supreme Court, after critics—including political figures—challenged it in court.

The New York example underscored the disparity: in the United States, aerial spraying is employed preventively, before outbreaks spiral out of control. In Brazil, health authorities often dismiss such technology even in emergency situations. By September 20 of this year, Brazil had already recorded more than 1.5 million dengue cases, with 1,646 confirmed deaths and another 307 under investigation. The Health Ministry also reported 3,739 cases of Zika (with no deaths) and 121,803 cases of Chikungunya, which caused 113 confirmed fatalities and 73 more under investigation.

AIRCRAFT: A helicopter was the aircraft chosen for application flights over wetlands in New York neighborhoods – photo: montage with Minnesota Mosquito Control aircraft on maps of operations in New York