Piracicaba’s Epidemiologic Surveillance service released new data this week which showed a 91% reduction of dengue fever cases registered in the CECAP/Eldorado district, an area of 5,000 residents, in the 2015/2016 dengue-year as compared to the 2014/2015 period.

The incidence decreased to just 12 cases in 2015/2016, the first year in which Friendly™ Aedes, the genetically engineered mosquitoes that fight wild Aedes aegypti, were released there, versus 133 cases in the previous year. According to Epidemiologic Surveillance the rest of the municipality saw a 52% reduction in dengue fever incidence during the same period, from 3,487 cases in the 2014/2015 period to 1,676 cases in 2015/2016.

Additionally, the overall incidence rate in CECAP/Eldorado for the dengue-year 2014/2015 was 195% larger than the rate recorded for the rest of the municipality. In the dengue-year 2015/2016, the rate in CECAP/Eldorado was 45% lower than the rate in the rest of the municipality. The latest data roundup also reports zero cases of Zika and chikungunya in CECAP/Eldorado.

“Over the course of one year, we were able to bring the dengue fever incidence down by more than 50% in Piracicaba — the outcome of diligent work to eliminate still water spots, the breeding site of the mosquito,” says the city’s Secretary of Health,Pedro Mello. “In CECAP/Eldorado, where we had the Friendly™ Aedes project, the reduction was extraordinary, going over 90%.”

“We are delighted with the result achieved so far by Friendly™ Aedes which shows the potential of our approach. We hope to see this effect on a larger scale beyond the limited area of CECAP/Eldorado with our expansion into Piracicaba’s downtown city,” says Glen Slade, Oxitec do Brasil director.

Oxitec has been working in Aedes aegypti control for more than a decade. It is a pioneer in the use of a biological method to suppress wild populations of this dangerous mosquito species through the release of Friendly™ Aedes males, which don’t bite and don’t transmit disease. When released, these males search for wild females to mate, and their offspring inherit a self-limiting gene that makes them die before reaching functional adulthood.

Aedes aegypti Image/CDC
Aedes aegypti
Image/CDC