Dengue has been one of the Philippines’ largest epidemic problem, with over 33,760 cases reported this year. It causes fever (which is often mistaken for the flu), mild bleeding, rashes, and nausea; and in some cases, death. Then in 2016, the Zika virus became an international health emergency in some parts of the world.

A new breed of mosquitoes that are intended to fight dengue was released from the Fiocruz Institute in Rio de Janeiro last Tuesday. The mosquitoes were intentionally infected by bacteria meant to prevent the insects from transmitting the dengue virus to humans. According to Fiocruz, they are planning to release 1.6 million infected mosquitoes every week.

Scientists from Australia developed and put the Wolbachia bacteria into mosquitoes since last year. The goal for the mosquitoes is for them to breed and spread the bacteria, affecting the mosquito population’s ability to further spread viruses similar to dengue like Zika and chikungunya.

“The idea is that when [the mosquitoes] are released, they will transmit this, as if they were immunizing the other mosquitoes and therefore transmission will be reduced,” says Luciano Moreiro, head of the dengue program at Fiocruz.

Photos courtesy of Inquirer.net and NBC News