Floods, Rainfall Bring Abundance of Mosquitoes to Nebraska This Summer


June 28th, 2019

Photo: Anders bjurnemark/Wikimedia Commons

OMAHA, Neb. – It’s National Mosquito Control Awareness Week, and health officials both here and nationwide hope to further educate the public about what they can do to protect themselves and others against mosquito-borne diseases like West Nile virus.

Last year, Nebraska had more human cases of West Nile than any other state, reporting 245 cases, 11 of them fatal. Douglas County had a record 71 of those cases with one death. 

Standing water is a breeding ground for mosquitoes, and the flooding and rainfall in the Midwest this spring has led to a lot of standing water and, thus, an increased number of breeding sites. 

“There is more of a population this year than what we had going into last year and that’s pretty much to be expected with the amount of rainfall that we’ve had. It’s been pretty good conditions for mosquitoes,” says Russ Hadan, an environmental supervisor with the Douglas County Health Department.

“If we continually have this rain every week or so with an inch or two and the ground’s already kinda saturated, you end up just having a whole bunch of breeding grounds for those mosquitoes that like the flood-type waters.”

Naturally, these flood-type species of mosquitoes, says Hadan, are abundant in Nebraska this year, and there have been several species of the Culex genus reported by health departments across the state. Certain species of Culex are frequent vectors of West Nile.

Douglas County has been trapping and testing mosquitoes since late March and testing dead birds since June 1 for signs of West Nile. Hadan says the virus has not been found in either of these test groups; further, data shows that no instances of West Nile have been found statewide so far in 2019.

And while mosquito populations may be higher than normal due to floodwaters and rainfall, Hadan explains why wetter conditions may not necessarily lead to increased cases of West Nile.

“A lot of times when you have a drier year, there’s less areas for birds to congregate and so they’ll start going in one area,” he says. “The Culex mosquito actually likes to feed on birds – that’s the first step in West Nile, is that it feeds on a bird, gets the West Nile virus, and then feeds on humans. There’s that possibility with more water sitting around that birds won’t congregate together as much and maybe the instance of West Nile may go down.”

In fact, several scientific studies in recent years have shown that West Nile epidemics are most severe in drought conditions, and this congregation of birds and mosquitoes around limited sources of water could indeed be a contributing factor.

Nevertheless, people should still take care throughout the summer to protect themselves from mosquito-borne diseases. To guard against mosquito bites, the American Mosquito Control Association recommends following the Three Ds: drain water containers at least once a week, dress in long, light-colored and loose-fitting clothing, and defend against the insects using a CDC-approved repellent. 

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