A recently published study from Iowa State University medical entomologists found transmission of West Nile virus most often occurs in Iowa’s western counties, where the data also found the heaviest concentrations of the mosquito species most often identified as the vector of disease transmission.

The ISU Medical Entomology Laboratory identifies thousands of mosquitoes every year collected in traps across Iowa. A recent study based on 15 years of mosquito surveillance data reveals insights about the transmission of West Nile virus in Iowa.
Image/Iowa State University News Service

The study, published this week in the academic journal Scientific Reports, drew on 15 years of data collected by mosquito surveillance efforts led by the ISU Medical Entomology Laboratory. The research found the species Culex tarsalis, which is most often associated with transmission of West Nile, is more abundant in Iowa’s western-most counties. 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, assistant professor of entomology and director of the medical entomology laboratory. The study also examined the intensity of West Nile virus infection in humans and mosquitoes in Iowa over the last 15 years, which peaks in early September.

An ongoing concern

Smith said the study should reinforce for Iowans that West Nile remains a real concern in the state, with transmission of the disease occurring every year.

“This is the most comprehensive study of West Nile virus transmission in the state since the virus was first introduced here,” Smith said. “It’s a reminder to Iowans that this virus is here and probably isn’t going away anytime soon.”

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