Day 6 Encore: Could genetically modified mosquitoes stop the Zika virus?

This week, the U.S. FDA released a final environmental assessment for a field trial that would release genetically modified Zika-killing mosquitoes in Florida.

The limited approval is a small but significant step the British company behind this radical solution.

The company is Oxitec and the plan is to create a breed of giant, genetically modified aedes aegypti mosquitoes, the main carrier of both Zika and dengue.

The technology has already been approved for pilot projects and commercial use in other countries including Brazil but some people, like Helen Wallace of GeneWatch U.K., are concerned about its impact but the  FDA's final environmental assessment says it "will not have significant impacts on the environment."

All this comes as the Summer Olympics get underway in Rio de Janeiro, where the outbreak started last year and where fear of the Zika virus is still first among concerns by visiting athletes and fans.

In most cases, Zika has few or no symptoms and there is still no treatment for it.

Brazil's sports minister has tried to alleviate some of that fear, saying there will be "close to zero" cases of Zika during the games.

Those words will likely not bring much comfort to athletes and tourists in Rio. The World Health Organization declared the Zika virus a global emergency months ago.

Earlier this year, The Centers for Disease Control and Prevention confirmed that Zika causes microcephaly - a birth defect which causes infants to be born with abnormally small heads.

This week on Day 6, we revisit a conversation between Brent and Oxitec's CEO, Hadyn Parry, about how his genetically modified mosquitoes could help combat Zika — and whether they are safe.