NEWS

Southwest Florida mosquito control prepping for Zika

Frank Gluck
FGLUCK@NEWS-PRESS.COM

Tom Miller places a bucket-sized cylinder filled with dry ice at the base of a mango tree in the Tice residential neighborhood just east of Fort Myers.

The carbon dioxide wafting out is bait. The trophy: Mosquitoes, including the Aedes aegypti and Aedes albopictus varieties known to spread dengue fever, chikungunya and, potentially in the wet months ahead, the Zika virus.

Miller, a Lee County mosquito surveillance investigator, has already placed four traps within two miles of this spot on this day. The broader area, home to a large immigrant community, has reported a number of suspected Zika infections this year in residents who have visited Central and South America, he said.

Mosquito monitoring is a year-round routine. But Miller and his fellow investigators are about to get much busier. Summer is coming, and Zika's link to crippling birth defects in Central and South America has added an extra urgency to this year's effort.

“It’ll be worse once it starts raining. We’ll get a lot,” Miller says while placing a trap across the street from a county park and a school bus stop. “It’s just a matter of time before a mosquito is going to bite someone who has it.”

Florida began seeing its first Zika cases in January, after travelers returned home after getting infected in countries experiencing Zika outbreaks.

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Since then, the state has reported a steady stream of new travel-related infections, most in Miami-Dade and neighboring Broward counties. Seven pregnant women were infected, though state officials have not said where they live.

Lee County has counted four of the state’s 102 Zika cases this year. Collier has confirmed one case.

Public health officials have every reason to believe that Florida, which has confirmed the most U.S. Zika cases, will soon see its first Zika case resulting from a local mosquito.

Consider recent history:

Domestically acquired cases of West Nile virus, first seen in North America in 1999, are not uncommon. Chikengunya, which affected few U.S. travelers before 2006, began spreading in Florida in 2014.

Outbreaks of dengue fever, which had been eradicated from the United States decades ago, were reported in Key West in 2009 and in Martin County in 2013.

Mosquito-borne diseases such as eastern equine encephalitis infect a few Floridians every year.

For now, experts assume Zika will be similarly rare once it establishes itself in Florida.

“I’m certain that we will see cases here, locally transmitted cases,” said Dr. Amy Vittor, with the University of Florida's Emerging Pathogens Institute. “The extent of it? My estimation – and we’re all estimating at this moment – is that it won’t cause the kind of epidemics we’ve seen in Brazil and Central America.”

Let's not panic over Zika virus

Vittor said Florida benefits from generally robust mosquito awareness and eradication programs. It also helps that buildings here are commonly air conditioned and screened, allowing people to comfortably spend time indoors. But she said the risk is not zero, especially for pregnant women.

“What the data show right now is, the rate of the infant being affected in some way, not necessarily microcephaly, is actually fairly high," Vittor said. "One small study indicated that it may be in the order of about 30 percent — 20 to 30 percent — of mothers who get infected who end up having a baby with some sort of anomaly.”

Dr. Celeste Philip, Florida's interim surgeon general, said state officials are taking that threat "very seriously."

“The fact that this is the first virus that we’ve seen in over 50 years that could impact the neurological development of fetuses is very disturbing," Philip told The News-Press. "We have a very large population in Florida, lots of babies are born here each year, so I think the concerns that are felt around pregnant women, young families, communities that might have to deal with any of these neurological deficits, such as microcephaly, it is very concerning.”

Zika plan

Lee County’s mosquito control and public health agencies say they have plans on paper, should the worst occur.

“I think we’re prepared as best we can be,” said Shelly Redovan, spokeswoman for the Lee County Mosquito Control District. “But I would be making light of things by saying that anybody is 100 percent ready for this if it goes to local transmissions that spread.”

This is the strategy:

When a person has a suspected infection, usually after reporting Zika-like symptoms and recent travel to a country with outbreaks, a doctor's office or hospital will ideally notify the Florida Department of Health.

The department is then supposed to notify the mosquito control district and provide surveillance investigators with the general location of the sick person's residence.

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Mosquito control lays traps in the area to sample the local mosquito population. If the person tests positive for the disease, the district deploys ground vehicles to spray within a half mile of the case for two successive nights. The disease-spreading mosquito tend to fly only a few hundred feet.

If a local infection is confirmed, the district would begin evening aerial spraying of the area. The next day, the district would drop denser larvicide over the area, to better reach the wet nooks and crannies mosquitoes use to reproduce.

Mosquito investigators would then follow up with neighborhood trap surveillance to look for more signs of mosquitoes carrying the virus.

Some daytime spraying over residential areas — generally avoided to protect pollinating bees and considered unnecessary in normal circumstances — might take place if local Zika infections increase in number, Redovan said.

If local transmissions begin to pop up, particularly if they are seen in multiple parts of the county, mosquito control has considered diverting resources from other pest control or hiring temporary employees to help with surveillance and eradication efforts.

Because the insecticides most commonly used has a limited effect on disease-spreading mosquitoes — one surveillance study in Lee County found it reduced only 70 percent of the adult population — It might also have to stock up on additional, and expensive, insecticides.

The district generally spends about $2 million a year on mosquito control chemicals. This year, it has also purchased 275 pounds of larvicide, which cost $9,200 and could cover one square mile.

"If we have some (cases of local Zika transmission throughout the county), we'd have to order a lot more of that material," Redovan said.

Public education

Gov. Rick Scott declared Zika to be a public health emergency in February, shortly after its discovery in several Florida counties, including Lee.

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Scott will travel to Washington next week to urge lawmakers to accept the Obama administration's request for $1.9 billion to combat Zika.

"We are now headed into summer, when heat and rainfall cause our mosquito population to grow," Scott said Wednesday. "Simultaneously, the Olympic games in Brazil will heavily increase travel to a country where the Zika virus is spreading rapidly."

It's unclear how much of that money Florida would get, though it would like be divided based on Zika risk, according to the Florida Department of Health.

Dr. Phillip, the interim surgeon general, said the funds would likely be used to expand mosquito laboratory capacity, studies to determine what Florida regions have the biggest the mosquito threat and to support mosquito control districts in areas hard-hit by any local Zika transmissions.

In the meantime, health departments offices in Lee and Collier have provided educational lectures on Zika to county employees and first responders, said spokeswoman Mara Gambineri. She said they have also created educational brochures for outreach to the local Hispanic community using WIC clinics, and worked with local hospitals on rules for collecting test samples.

Lee Memorial Health System, which operates nearly 95 percent of Lee County's acute-care hospital beds and scores of specialty and outpatient throughout Southwest Florida, has instructed hospital and clinic staff to question patients with Zika symptoms about their recent travel, said Steve Streed, the organization's director of infections control.

Preventing secondary infections are the priority, Streed said.

“I am concerned because, if we have a lot of people come in and some don’t present (symptoms) and they’re sitting on their lanai next to the pool, there could be secondary (infections)," Streed said. “Their disease might be minor, but the secondary cases — it might be a neighbor who gets bitten and she might be pregnant.”

Big budget, wrong pest

The Lee County Mosquito Control District is the largest district in Florida, with an annual budget of $17.5 million and 87 full-time employees. But it was not set up to fight disease-spreading pests.

Rather its vast resources, including 15 aircraft (11 helicopters and four planes) and more than 100 ground vehicles (20 are dedicated to mosquito control), largely fight another menace: the salt-marsh mosquito, an aggressive but non-disease-spreading pest.

Lee County has 60,000 acres of salt marsh, more than the combined amount of five counties directly to the east.

"They are vicious, they grow in bazillions of numbers and they can fly 40 miles," said T. Wayne Gale, executive director of the Lee County Mosquito Control District. “The Zika mosquitoes — the Aedes aegypti and Aedes albopictus — they might fly a couple of blocks. Salt marsh mosquitoes can cover the whole county.”

Still, the district has adjusted to its growing public health role.

It is the only district to have its own laboratory to test mosquitoes for the presence of disease. Aside from traps to monitor Zika, it deploys "sentinel" chickens in various locations to look for signs of West Nile,St. Louis Encephalitis, and Eastern Equine Encephalitis that circulate in avian populations.

Given that, Gale said he's not worried about this summer.

“I’m no more concerned about Zika than I am about dengue or some of these other diseases," Gale said. "These things seem to be somewhat cyclic in nature.”

Connect with this reporter: @FrankGluck (Twitter)

Keeping mosquitoes at bay

Start, by preventing them from coming indoors: Mosquito control experts say the best way to do that is to use air conditioning, keep doors and windows shut and repair any holes in door and screens.

Stop them from breeding: Disease-spreading mosquitoes breed by laying eggs in and near standing water. They need as little as one teaspoon (or bottle cap-full) of water undisturbed for about a week. Turn over and cover tires, buckets, toys, roof gutters, birdbaths and anything else that can hold water.

Know your garden: Flower pots and saucers should be clear of standing water. Some common plants, such as bromeliads, hold water too and should be flushed out with a hose at least once a week.

Zika symptoms and treatment

Only one in five people infected with the Zika virus show any symptoms. When symptoms do show up they tend to be mild in nature.

They include acute onset of low-grade fever, rash, joint pain, conjunctivitis (reddening of eye), body aches, headache, eye pain, and vomiting. There is no treatment for Zika, but the illness usually goes away after a week.

Recommendations for pregnant women

Pregnant women should avoid traveling to countries where Zika is spreading and should use a condom with a partner who has recently traveled to such a country.

If they have returned from such countries or had unprotected sex with a person who has, they should see their doctors if they exhibit any Zika symptoms.

Even those not traveling should take steps to avoid mosquito bites, including wearing insect repellent and protective clothing while outdoors.

Sources: Florida Department of Health, Centers for Disease Control and Prevention

Tom Miller, an employee of the Lee County Mosquito Control leaves a mosquito trap in a neighborhood off of Palm Beach Boulevard near Ortiz Avenue on Wednesday 4/28/2016.  The trap catches the types of mosquitos that could carry the Zika virus.
Tom Miller, an employee of the Lee County Mosquito Control leaves a mosquito trap in a neighborhood off of Ortiz Avenue  on Wednesday 4/28/2016.  The trap catches the types of mosquitos that could carry the Zika virus.
Tom Miller, an employee of the Lee County Mosquito Control leaves a mosquito trap in a neihborhood off of Palm Beach Boulevard near Ortiz Avenue on Wednesday 4/28/2016.  The trap catches the types of mosquitos that could carry the Zika virus.