The Food and Drug Administration (FDA) is currently reviewing a proposal to release millions of genetically modified mosquitoes in the Florida Keys to stop the spread of dengue and chikungunya. Both diseases are transmitted by female Aedes aegypti (also known as yellow fever mosquitoes), which have become resistant to four out of the six insecticides that are used to kill them.

The British biotech firm Oxitec has patented a method for breeding Aedes aegypti with proteins from the herpes simplex virus and E. coli bacteria, along with genes from coral and cabbage; this synthetic DNA is fatal to the mosquitoes and kills the larvae before they can fly or bite. Only the male modified mosquitoes are released, where they mate with wild females whose offspring die.

If approved by the FDA, a field test will be conducted in Key Haven, FL that will be similar in size to a 2012 experiment in the Cayman Islands that suppressed 96% of the targeted mosquitoes. Critics have voiced concerns over the potential –  albeit small risk –  for genetically modified DNA to enter a human who has been bitten by a female that has been accidentally released with the modified males, while others state that the benefits of preventing the spread of these diseases that have no vaccines or known cures outweigh the risks.