Dengue fever cases have been cut by 77% in a "groundbreaking" trial that manipulates the mosquitoes that spread it, say scientists.
Few people had heard of dengue 50 years ago, but it has been a relentless slow-burning pandemic and cases have increased dramatically.
Dengue is commonly known as "break-bone fever" because it causes severe pain in muscles and bones and explosive outbreaks can overwhelm hospitals.
The trial used mosquitoes infected with Wolbachia bacteria. One of the researchers, Dr Katie Anders, describes them as "naturally miraculous".
Wolbachia doesn't harm the mosquito, but it camps out in the same parts of its body that the dengue virus needs to get into.
The bacteria compete for resources and make it much harder for dengue virus to replicate, so the mosquito is less likely to cause an infection when it bites again.
The trial used five million mosquito eggs infected with Wolbachia. Eggs were placed in buckets of water in the city every two weeks and the process of building up an infected population of mosquitoes took nine months.