Surprise! Faced with Zika, South Florida fosters a mess of mosquitoes

The Zika outbreak in Miami has pointed out what Floridians and vacationers have known for years: There is no shortage of mosquitoes in the Sunshine State.

White House press secretary Josh Earnest told reporters at an Aug. 3 briefing that the region’s experience in fighting the bloodsucking insects will help efforts to prevent the further spread of the virus. At last count, the state had 338 travel-related cases of Zika, but there have been at least 15 locally transmitted instances — 13 in Miami and two in Broward County.

"We know the mosquito population in South Florida is larger than it is in many other communities in the country," Earnest said. He added that prior experience dealing with other mosquito-borne diseases has established the expertise for how to deal with outbreaks like this one.

As anyone who has ever attended an outdoor concert or Little League game can confirm, Florida sure does have a lot of winged menaces. But do we really have more than most other communities?

PolitiFact Florida didn’t have to go camping in July to quickly learn that the answer is unequivocally yes, for many reasons.

A vacation for vectors

Zika is a virus named after the Zika Forest in Uganda, where it was first discovered in 1947. Several cases were documented in Africa and Asia over the decades until the disease made it to a couple of Pacific island nations in 2007 and 2013.

The current pandemic took off in May 2015, when Brazil reported cases of Zika in connection with an increase in babies being born with abnormally small heads, a condition called microcephaly. With evidence that the disease can be spread both through sexual contact and via mosquito bites, the Centers for Disease Control and Prevention says there are more than 50 countries and territories with active Zika transmissions. The World Health Organization provides periodic updates of cases, and has tracked hundreds of thousands of confirmed and suspected infections in the Americas.

Symptoms of the virus include fever, rash, joint pain and headaches or muscle pain, although almost four out of five infected people don’t show symptoms. There is no treatment or vaccine for the disease, so focus has been on prevention. The CDC has issued a travel warning for pregnant women and their partners to not travel to Wynwood, the neighborhood north of downtown Miami where the new cases appeared.

About those mosquitoes

A main culprit for the spread of the disease is mosquitoes, especially a species called Aedes aegypti. It is known for carrying tropical maladies like yellow and dengue fevers.

Aegypti is not a fan of cold, northern winters. It lives across the southern United States, where it can generally survive all year long. That means the insect is just as fond of Florida as the snowbirds and sunbelters it feasts upon.

The White House did not specify to us whether Earnest meant Florida had the most mosquitoes or the most different kinds of mosquitoes, but experts told us that’s largely irrelevant.

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What Earnest said is that the mosquito population in South Florida is larger than many other places in the United States, and that’s undoubtedly correct.

The Sunshine State is a veritable mosquito encyclopedia, with about 80 species found here. American Mosquito Control Association technical adviser Joe Conlon, a retired Navy entomologist, pointed out Texas has 85 species, but "when you’re talking about 80 versus 85, it doesn’t matter; it’s a lot."

Exactly how many individual mosquitoes are in any one place is an uncountable number. There’s no way to take a comprehensive mosquito census, although there are ways to get a rough idea.

Various traps can count eggs and larvae in standing water, or the number and species of captured adult mosquitoes and extrapolate from there. Florida’s 61 mosquito control programs regularly conduct such surveys to determine if they need to spray or raise public awareness about preventing mosquito populations from growing.

Of course, aegypti is an especially sneaky species that is notoriously difficult to count, Conlon said. Individuals can breed in multiple places, and adults tend to avoid traps. (Note: Only female mosquitoes bite.)

If you’re wondering whether Florida is the most popular home for the particular aegypti species, there’s just no way to know that. New Orleans, for example, historically has more aegypti in terms of sheer numbers. That city and Memphis, Tenn., have experienced major mosquito-borne outbreaks in the past.

That’s because mosquitoes flourish in hot climates with lots of standing water. Florida’s heat, humidity, rainfall and topography combine to make the state a garden spot for more than just New Yorkers escaping state income taxes. With salt marshes, the Everglades and plenty of man-made pools of water, South Florida faces an even bigger threat.

"Indeed, they have some of the worst mosquito problems on Earth there," Conlon said.

Even if there were a way to take a comprehensive count of mosquitoes in an area, that number would never remain constant.

"Mosquito populations fluctuate over time and at any given point in time the mosquito population in Newburyport, Mass., may be greater than that in North Miami," University of Florida Entomologist Jonathan Day, of the Florida Medical Entomology Laboratory in Vero Beach, told us in an email. "However, over the long run (for example, an entire year), South Florida mosquito populations are likely consistently higher than those observed in other communities in the country."

Our ruling

Earnest said, "The mosquito population in South Florida is larger than it is in many other communities in the country."

There’s little doubt about that. Mosquito populations can go up or down anywhere, but experts said the conditions in South Florida sustain a large and diverse collection of the insects essentially all year long. Be safe out there, and don’t forget the DEET.

This may not be a biting revelation, but we rate it True.

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