Brazil is trying to prevent the spread of dengue fever by releasing mosquitoes carrying bacteria capable of controlling the virus.
Dengue fever is a mosquito-borne disease that causes high fever and severe headaches, as well as pain in muscles and joints.
The city of Rio de Janeiro recently started releasing a large number of mosquitoes artificially infected with the Wolbachia bacteria. The bacteria are said to be effective in suppressing the growth of the dengue virus.
The mosquitoes are expected to significantly reduce infections as the bacteria can be transmitted to the insects' offspring.
The city plans to release about 12 million Wolbachia-carrying mosquitoes by August.
The South American country has confirmed more than 3.3 million cases of dengue fever and 1,457 deaths so far this year. Both figures have already exceeded last year's totals, and are the highest since record-keeping began in 2000.
The project is overseen by Gabriel Sylvestre, the head of the Brazilian office of the non-profit World Mosquito Program. He says he hopes to expand the bacteria method across the country.