Lost among reports of the first locally transmitted cases of the Zika virus in the continental United States in late July (as well as concern over Zika transmission at the 2016 Summer Olympics in Rio de Janeiro, Brazil in August), was an announcement last month regarding the U.S. Food and Drug Administration's completion of an environmental review for a proposed field trial of genetically engineered mosquitoes.  The field study will be conducted to determine whether the release of genetically engineered (GE) mosquitoes made by Oxitec Ltd., a British biotechnology company that develops genetically modified insects to assist in insect control, will suppress the local Aedes aegypti mosquito population in the release area at Key Haven, Florida.  The GE mosquitoes carry a self-limiting gene, so when male GE mosquitoes are released into the wild and mate with wild females, their offspring inherit the self-limiting trait.  The resulting offspring will die before reaching adulthood, and the local mosquito population will decline.

The FDA noted that after considering thousands of public comments submitted in response to the agency's draft environmental impact study, the FDA was able to publish a final environmental assessment, entitled "Environmental Assessment for Investigational Use of Aedes aegypti OX513A," and "Finding of No Significant Impact".  The FDA indicated that the latter report agrees with environmental assessment that the proposed field trial will not have significant impacts on the environment.

In making the announcement, the FDA also noted that the release of the environmental assessment and report of no significant impact did not mean that Oxitec's GE mosquitos are approved for commercial use.  Instead, Oxitec will still be responsible for ensuring that all other local, state, and federal requirements are met before conducting the proposed field trial.  Oxitec is partnering with the Florida Keys Mosquito Control District in conducting the proposed field trial.

As of last week, the Centers for Disease Control and Prevention reports that there have been 43 cases of locally acquired mosquito-borne Zika virus in the United States and 17,629 cases of locally acquired mosquito-borne Zika virus in U.S. territories.  All of the U.S. cases to date have been in Florida.