Scientists at the Fiocruz research institute in Rio de Janeiro, Brazil have been working on a way to fight the spread of the tropical disease. They have released thousands of mosquitoes that are infected with a bacteria called Wolbachia, which acts as a vaccine for the dengue fever in mosquitoes that aren’t yet carrying the infectious disease.

Estimates say that every year about 390 million people get dengue fever with symptoms like joint pain and headaches.

Scientists at the Oswaldo Cruz Foundation, a research institute known as Fiocruz in Rio de Janeiro, Brazil have been working on a way to fight the spread of the tropical disease.

They have released thousands of mosquitoes that are infected with bacteria called Wolbachia, which acts as a vaccine against the infectious disease by both halting its reproduction in host mosquitoes, as well as preventing them from passing it on to their larvae.

Researchers will release thousands of mosquitoes carrying the Wolbachia bacteria every month over the course of the next four months.

Luciano Moreira of Fiocruz, who is leading the project in Brazil is quoted as saying: "Our teams performed weekly visits to the four neighborhoods in Rio being targeted. Mosquitoes were analyzed after collection in special traps. Transparency and proper information for the households is a priority.”

The mosquitoes being released in Brazil are part of a plan that is also being implemented in Australia, Vietnam and Indonesia.

Scientists hope that if enough mosquitoes have the dengue-blocking bacteria, that it will eventually spread and wipe out the source of the disease for humans.