A study led by UC Santa Cruz researchers has found that drought dramatically increases the severity of West Nile virus epidemics in the United States, although populations affected by large outbreaks acquire immunity that limits the size of subsequent epidemics.
The study, published February 8 in Proceedings of the Royal Society B, involved researchers from UC Santa Cruz, Stanford University, and the New York State Department of Health.
They analyzed 15 years of data on human West Nile virus infections from across the United States and found that epidemics were much larger in drought years and in regions that had not suffered large epidemics in the past.
"We found that drought was the dominant weather variable correlated with the size of West Nile virus epidemics," said first author Sara Paull, who led the study as a post-doctoral researcher at UC Santa Cruz and is now at the National Center for Atmospheric Research.
In the new study, Paull and Marm Kilpatrick, an associate professor of ecology and evolutionary biology at UC Santa Cruz, analyzed patterns in the number of severe West Nile virus infections each year in each state and nationally.
Model projections indicated that increased drought could double the size of future West Nile virus epidemics, but that outbreaks would be limited to regions that have yet to sustain large numbers of cases.
"Drought identified as key to severity of West Nile virus epidemics: Study finds transmission of West Nile virus is higher in drought years, but after large outbreaks acquired immunity limits the size of subsequent epidemics."
ScienceDaily, 7 February 2017.
Drought identified as key to severity of West Nile virus epidemics: Study finds transmission of West Nile virus is higher in drought years, but after large outbreaks acquired immunity limits the size of subsequent epidemics.
"Drought identified as key to severity of West Nile virus epidemics: Study finds transmission of West Nile virus is higher in drought years, but after large outbreaks acquired immunity limits the size of subsequent epidemics."