San Diego County hasn't seen any human cases of West Nile virus so far in 2015.
But county officials say it's too soon to let our guard down.
Seventy three dead birds infected with West Nile virus have been discovered in San Diego County so far this year. That’s more dead birds than were found in all of 2014.
Greg Slawson, a senior vector ecologist with the County Department of Environmental Health, said West Nile is generally a late summer disease, when mosquito activity is highest.
"The lion's share of the positives are usually between right about now, August through September, and even into October sometimes," Slawson said.
As of Aug. 9, there have been 19 Californians infected with West Nile virus in 2015. Statewide, there has been only one death linked to the disease this year.
