The deadly flood that has swamped south Louisiana this week will likely mean more mosquitoes this summer as the floodwaters start to recede.
State health leaders say that also could mean an increase in West Nile cases and even potentially a bigger threat of Zika virus.
"We're going to have standing water all over south Louisiana," Gov. John Bel Edwards said this week, warning about the additional pitfalls that lie ahead as the flood-affected areas transition to recovery mode. "We're going to have more than our share of mosquitoes."
The historic flooding, which is the result of what experts are calling a one-in-1,000-year rain, has prompted federal disaster declarations in 20 parishes. Edwards has said he expects that declaration will grow to cover even more as the flood waters shift southward and local officials tally up the damage their areas have sustained.
As Louisiana residents look east to the Zika outbreak in Florida, local health and mosquito …
No human cases of West Nile have been reported in Louisiana this year, but the virus has been detected in non-humans, meaning mosquitoes, birds or other creatures here have tested positive in 2016. But that could quickly change with a spike in mosquito activity.
"Standing water is mosquito heaven," State Health Secretary Dr. Rebekah Gee said. "Given this is the height of mosquito season, we have to be really cautious."
Typically, officials warn people to empty containers and other receptacles for standing water to eliminate places where mosquitoes can breed. Those rules will still apply, there will just be more opportunities for standing water when as the flooding goes down, said Dr. Frank Welch, the medical director for community preparedness for the Louisiana Department of Health.
Twenty parishes are now covered under a federal disaster declaration in response to severe f…
Welch said that many larvae may have been washed away by moving water from the storm, creating a lull in the mosquito population, but it won't last long.
"We tend to see an increase two-to-four weeks after a flooding event," he said.
Leaders say that will put the state at risk for mosquito-borne illnesses, including West Nile.
A report published by the Centers for Disease Control and Prevention found that there was a sharp increase in West Nile cases in Louisiana after Hurricane Katrina that was likely attributable to the storm.
It could also potentially have an impact on the spread of Zika here, though less so than West Nile because of the specific types of mosquitoes that carry the virus. Those are more likely to be found near Lake Pontchartrain, but Welch warned that increased rain in the area could also cause a spike there. Louisiana, to date, has recorded no cases of mosquito-borne Zika cases.
The federal disaster declaration will provide additional assistance for those parishes covered.
One of the points Edwards repeatedly stressed to local leaders during a trip to Lafayette, Iberia and Vermilion parishes earlier this week was that federal assistance would be available for mosquito control and abatement through the federal declaration. He urged them to seek additional protection because of the additional threat.
FEMA will cover up to 70-90 percent of the costs of additional abatement measures — meaning any additional efforts to curb the mosquito population on top of normal control measures will mostly be covered by federal dollars.
"That will be instrumental in lowering our risk," Gee said.
Gee said that federal assistance will also help cover LDH's additional lab costs for testing for the viruses, as well as community outreach efforts to inform the public about the increased risks.
Some local officials said they are already bracing for an increase in non-disease carrying mosquitoes, commonly called nuisance mosquitoes. Those are the mosquitoes that bite and leave itchy welts but are unable to infect people with viruses like West Nile or Zika.
Tangipahoa Parish mosquito abatement director Dennis L. Wallette Jr. said mosquito control in Tangipahoa was closed for a couple of days during the flooding, and lots of road closures meant that trucks couldn’t get everywhere.
He said his biggest concern will be floodwater mosquitoes, which lay their eggs on damp soil. “Any egg that’s out there will have been flooded, and we do expect a sizeable hatch-off,’’ Wallette said.
But he noted that the floodwater may actually end up carrying some larvae further downstream, so it’s possible that it will not be as bad as they’ve seen after other events.
Vickie Taylor, director of St. Tammany Parish mosquito abatement, said she also expects an infestation of woodland and marsh mosquitoes.
“There are going to be a lot of floodwater mosquitoes," she said.
East Baton Rouge Parish mosquito abatement director Todd Walker said about a third of his staff has been affected by the flooding, creating some manpower issues.
He estimated that the area has had a smaller mosquito population this summer, compared to past years, based on the number of calls for service.
Aside from standing water left behind in homes, swimming pools and containers, Walker said that pastures could become a breeding ground for mosquitoes — even an indentation from a hoof can create a place for mosquitoes to breed.
Walker said that East Baton Rouge has the chemicals and equipment it needs. The plan will be to treat the area by plane, which can cover larger areas more quickly, he said.