Bob Decker was ready to start playing golf early one morning this summer when he headed to Steve Hogan Golf Course in Omaha.
Instead, he provided swarms of mosquitoes with breakfast, lunch and dinner during his round on the nine-hole course.
“I was knocking mosquitoes off my legs the whole time,” he said. “That’s the reason for my bad result…”
Decker isn’t imagining it. Compared to last year, mosquito numbers across Nebraska are up significantly, nearly doubling in mid-July. But what many people consider a nuisance could have serious consequences, especially as Nebraska enters peak season for the mosquito-borne West Nile virus.
The numbers have caused concern among health authorities, but the future is even more worrying.
Human-caused climate change is extending the season and range of mosquitoes worldwide. Mosquitoes are the world’s deadliest animal and are feared for the diseases they spread in tropical regions. But even places like Nebraska provide fertile habitat for certain disease-carrying species. And the situation is expected to get worse.
“When we talk about climate change, it obviously plays a role in the number of mosquitoes,” said Justin Frederick, deputy health director for the Douglas County Health Department. “The warmer the climate gets, the more these viruses spread.”
This year, the number of mosquitoes caught in traps in Nebraska is 66% higher than last year and remains above the five-year average, according to the Nebraska Department of Health. In mid-July, the numbers were up about 90%, according to the state.
The numbers are significant because mosquitoes, like ticks, can transmit debilitating and even fatal diseases, says Jody Green, an urban entomologist and lecturer at the University of Nebraska-Lincoln Extension in Douglas and Sarpy counties.
“Those two things are really important. Those are two things that can make people sick — they can really affect the health of Nebraskans,” she said. “That’s an important story, that’s why I have this job. I can help save people’s lives, I can help protect their health.”
The biggest mosquito-related concern in Nebraska is West Nile virus, but the state also monitors other dangerous mosquito-borne viruses for the potential for them to enter the state.
Most people who become infected with West Nile don’t know it. According to the U.S. Centers for Disease Control and Prevention, an estimated 70 to 80 percent of people with West Nile show no symptoms.
However, in a few cases, the disease can be fatal. Of the 2,566 cases reported nationwide in 2023, 1,840 required hospitalization and 182 died, according to the CDC.
Omaha resident Jenna Everhart is still mourning the loss of her friend Crystine Dozier, who was immunocompromised and died of West Nile in 2020. Everhart said she doesn’t spend as much time outdoors in the summer anymore.
“You don’t think that a mosquito could kill you until it happens to someone you know,” she said.
This year, the Culex mosquito, which carries West Nile virus, appeared in the Omaha area in June, much earlier than the usual mid- to late August, Frederick said. Douglas County also documented the state’s first West Nile case of the year in June.
During the week ending August 3, 14 cases of West Nile infection were reported in Nebraska. Eight of these cases required hospitalization.
At the state level, the Nebraska Department of Health and Human Services assesses the current threat from West Nile virus as moderate, but in southeastern and northern Nebraska the threat is high.
In recent years, mosquito-borne viruses have made headlines in Nebraska.
After Aedes aegypti, a species native to tropical regions, was discovered in traps in York in 2019 and Fairbury in 2020, public health officials launched concerted eradication campaigns.
Because this tropical mosquito species can transmit diseases such as chikungunya, dengue fever, Zika and yellow fever, authorities acted quickly to eradicate it. The species has not appeared in Nebraska since, “so there is no reason to panic,” Green said.
In July, the Jamestown Canyon virus was detected in Douglas County for the first time in the state’s history. The virus, which is transmitted by mosquitoes, often has a mild course but can cause serious illnesses such as inflammation of the brain and spinal cord.
Nebraska’s recent series of predominantly wet years and the trend toward warmer-than-average years have given the state an idea of how climate change can boost mosquito populations.
According to studies by the U.S. Environmental Protection Agency, in a warming world, mosquitoes mature and reproduce more quickly, bite more often and transmit diseases more easily.
Researchers suspect that above-average humid weather in Nebraska five years ago contributed to the introduction and survival of Aedes aegypti in York.
Studies have also found a link between alternating rainy and dry periods and West Nile outbreaks.
This wet-dry pattern was suspected of contributing to the rise in West Nile cases in Nebraska in 2018. That year, Nebraska was among the few states that recorded the most West Nile cases nationwide. According to the state, 13 people died from the virus, 113 were hospitalized, and a total of 251 were confirmed infected.
