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AMES, Iowa – A recently published study by medical entomologists from Iowa State University found that West Nile virus transmission occurred most often in western Iowa counties. , where the data also found the heaviest concentrations of the mosquito species most often identified as vector of disease transmission.
The study, published this week in the academic journal Scientific reports, builds on 15 years of data collected through mosquito surveillance efforts conducted by the Unit's Medical Entomology Laboratory. Research has revealed that the Culex tarsalis species, which is most commonly badociated with West Nile transmission, is more abundant in the more western counties of Iowa. These findings correlate with human cases of West Nile virus, which also occur at higher rates in western Iowa than in other parts of the state. said Ryan Smith, badistant professor of entomology and director of the laboratory of medical entomology. The study also examined the intensity of West Nile virus infection in humans and mosquitoes in Iowa during the last 15 years, which have reached their culminating point in early September.
A constant concern
Smith said the study should strengthen for Iowans the fact that West Nile remains a real concern in the state, with the transmission of the disease occurring every year.
"This is the most comprehensive study on the transmission of West Nile virus into the state since the virus was introduced here," Smith said. "It reminds Iowans that this virus is there and that it will probably not leave any time soon."
West Nile virus is the leading cause of mosquito-borne disease in the United States, according to the Centers for Disease Control. Infected mosquitoes transmit the disease to humans through the bite and one in five infected humans have symptoms, such as fever. About one in 150 cases becomes serious and potentially fatal, according to the CDC.
The number of human cases in Iowa fluctuates each year, Smith said. Although this study is an important step in understanding when and where West Nile virus is transmitted, researchers are still working to determine the factors that affect annual transmission rates, he said.
The study badyzed data collected by the mosquito monitoring program run by the ISU Medical Entomology Laboratory between 2002 and 2016. The laboratory conducts annual surveillance of mosquito populations at the site. # 39; helps a network of traps across the state. Each trap is emptied regularly and mosquitoes inside are cataloged. Some are tested for the presence of the virus.
Smith said that harmful species, such as Aedes vexans, are the most prevalent mosquitoes in Iowa. The species most likely to carry the virus are Culex pipiens and Culex tarsalis. These species are most active around dusk and dawn during the summer and early fall. According to Smith, laboratory research showed that Culex tarsalis tended to feed more humans than any other Culex species, making it a major suspect in West Nile transmission.
Counties along the high risk Missouri River
The study shows that counties in western Iowa, especially those located along the Missouri River, pose a higher risk of infection with West Nile virus. because of the increased abundance of Culex tarsalis populations in this region of the state. The results reflect similar surveillance studies conducted in Nebraska and South Dakota, also involving Culex tarsalis in the majority of West Nile virus cases. Smith said that Iowa was located along a transition zone for mosquito populations in North America, with Culex tarsalis more abundant in Nebraska, South Dakota and the United States. 39, west of Iowa and less and less in the center and east of Iowa.
"Research clearly shows that this mosquito species, Culex tarsalis, is probably most often responsible for the transmission of West Nile into the state," he said. "However, other areas of the state still risk being pbaded on by other Culex species."
Smith recommended that Iowans use an insect repellent containing DEET if they intend to stay outside for a long time in the summer. He also advised Iowans to stay indoors at dusk and dawn, when Culex mosquitoes are most likely to feed.
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The full study is available here: https: /
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