According to William K. Reisen, PhD, of the Center for Vectorborne Diseases at the University of California, Davis, and colleagues, the increase in West Nile cases is linked to the mortgage crisis. 

"A dramatic increase in home foreclosures and abandoned homes [has] produced urban landscapes dotted with an expanded number of new mosquito habitats," they report. "These new larval habitats may have contributed to the unexpected early season increase in West Nile virus cases in Bakersfield during 2007."

They feel that seemingly unrelated events can also trigger spread of a disease.

As a control measure, mosquito-control workers are trained to watch for neglected pools and spas. But these workers faced a tough time due to six-foot-tall fences and locked gates that local laws require around outdoor pools.

Aerial photographs showed that 17% of pools and hot tubs in some neighborhoods were green with algae. These would be a breeding ground for mosquitoes. The local authorities have stepped up the control measures but the problem persists.