Bacteria

Female mosquitoes are infected with Wolbachia, a bacterium that blocks transmission of the dengue virus and may also stop Zika. A research nonprofit has tested it in Australia since 2011—with smaller tests in Brazil, Colombia, and Southeast Asia.

Advantages The method could yield long-term cost savings because infected mosquitoes spread bacteria to each other.

Drawbacks There are no large-scale facilities in affected areas. More research is needed on the bacterium’s effectiveness.