By Alba Santandreu.

Roughly 800,000 genetically modified Aedes aegypti mosquitoes are being released per week in the Brazilian city of Piracicaba to combat that insect, a transmitter of the dengue and zika viruses that has confounded health authorities in Brazil and other Latin American countries.

Unlike other mosquitoes, the "good" Aedes aegypti, as it is colloquially known in Brazil, is welcomed by residents of the Cecap-Eldorado neighborhood of Piracicaba, a city in the interior of the southeastern state of Sao Paulo where the pilot program is being conducted.

The creation of British biotechnology company Oxitec, this mosquito was genetically modified in 2002 to impede the Aedes aegypti mosquitoes' territorial expansion and a year ago began to be used in Piracicaba to halt an increase in dengue cases in that city of 460,000 inhabitants.

Oxitec says that over the past eight months the number of Aedes aegypti larvae have been reduced by 82 percent in the neighborhood where the genetically modified insect was deployed, while the number of dengue cases has fallen from 133 to one.

"A lot of cities are getting into contact with us. The evaluation has been very positive," Sebastiao Amaral Campos, an agent with Piracicaba's Health Secretariat, told EFE.

Male genetically modified mosquitoes, whose commercialization is still pending approval by regulators, mate with females in the wild and transmit a self-limiting gene that causes the resulting offspring to die before reaching adulthood and thus diminishes the local mosquito population.

Authorities in Piracicaba turned to Oxitec's services as an alternative to the "failure" of traditional methods of combating female Aedes aegypti mosquitoes, which bite and can transmit dengue and zika.

The Aedes aegypti, which lay eggs in clean, stagnant water, sparked alarm last September when health authorities detected an increase in cases of microcephaly, a neurodevelopment disorder in which babies are born with a smaller-than-normal head size.

A total of 3,893 suspected cases of microcephaly, which could be caused by the zika virus or another infectious agent, have been registered nationwide, although thus far cerebral and skull deformities have only been confirmed in 224 cases, the Brazilian government says.

Around 100 cases of babies born with microcephaly were registered in Brazil last year, prior to the arrival of the zika virus in the South American country. EFE