Arizona Department of Health Services

Maricopa County Environmental Services is warning of the increased potential this year for West Nile cases.

A wetter-than-normal winter leads to ample vegetation, which can lead to more birds and more chances for the viruses they carry to spread.

West Nile and St. Louis encephalitis (SLE) is spread by mosquitoes that feed on infected birds and then transfer the disease to humans. John Townsend is the county’s vector control division manager.

“You get this amplification of either West Nile or SLE in nature and whenever it gets to a point, that’s when it spills over to the human population,” Townsend said.

Mosquitoes breed all year long in the desert, particularly in pooling water.