High bird diversity reduces risk of West Nile virus to humans
June 25, 2008
Areas with higher levels of bird diversity have lower incidences of West Nile virus infection in human populations, reports a new study published in the open-access journal PLoS ONE.
While the reasons for the findings are still being studied, the results support other research linking biodiversity to human health — specifically the “dilution effect” or the pattern “whereby increased biodiversity in wildlife results in lower risks of humans becoming infected by animal disease,” according to a statement from the University of California at Santa Barbara.
“We don’t yet know the precise mechanism that drives this pattern, but it’s likely to be due to diverse areas having relatively few of the bird species that are particularly competent hosts and reservoirs for the virus,” said John P. Swaddle, lead author of the study.
Swaddle and co-author Stavros E. Calos say that the species most likely to pass on the virus — rows, jays, thrushes and sparrows — are found in lower densities when overall bird diversity is high.
Swaddle says the findings suggest that small changes in land management could reduce the risk of West Nile by boosting bird diversity.
“Biodiversity is giving us a public health service that people have rarely considered and the value of this service should be considered when developing land and managing bird populations in the future,” Swaddle said.
According to the Centers for Disease Control and Prevention (CDC), between 2002 and 2007 there were more than 27,000 cases of West Nile reported in the United States, including over 1,000 fatalities.