Warmer Weather Could Bring More West Nile Virus to U.S.

News Picture: Warming World Could Alter West Nile Transmission in U.S.
TUESDAY, Sept. 29, 2020

Climate change could give West Nile virus a boost in some areas of the United States, but reduce its spread in other regions, a new study suggests.

The mosquito-borne virus spreads most efficiently in the United States at temperatures between 75.2 and 77 degrees Fahrenheit, according to a study published Sept. 15 in the journal eLife.

"As the climate warms, it is critical to understand how temperature changes will affect the transmission of mosquito-borne diseases," lead author Marta Shocket said in a journal news release. She conducted the research while at Stanford University, and is now a postdoctoral researcher at University of California, Los Angeles.

Shocket and colleagues performed laboratory experiments to assess how temperature affects West Nile. They found it's transmitted most readily at moderate temperatures.

The findings suggest that West Nile could take a greater toll in the United States as temperatures rise due to climate change, according to Shocket.

She explained that 70% of Americans live in areas that are currently below the optimal summer temperature for the spread of West Nile, but will likely have increased transmission with climate warming.

About 30% of the U.S. population live where summer temperatures are above the optimal temperature, meaning transmission will likely decrease with climate warming.

Climate change-caused temperature increases could also extend virus transmission seasons earlier into the spring and later into the fall, according to the researchers.

"Climate change is poised to increase the transmission of West Nile and other mosquito-borne viruses in much of the U.S.," said study senior author Erin Mordecai, an assistant professor of biology at Stanford University.

"But these diseases also depend on human contact with mosquitoes that also contact wildlife, so factors like human land use, mosquito control, mosquito and virus adaptations, and the emergence of new viruses make predicting the future of mosquito-borne disease a challenge," Mordecai added in the release.

-- Robert Preidt

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SOURCE: eLife, news release, Sept. 15, 2020.