California reports early West Nile virus.

The West Nile virus season is getting an early jump-start this year due to unusually high temperatures, according to California health officials.

As of mid-May, California had yet to report any human cases of the virus, but health officials reported that mosquitoes that carry West Nile virus are breeding earlier this year because of warmer weather.

"While no predictions can be made about the severity of West Nile virus this season, Californians should begin taking precautions to protect themselves from mosquito bites by eliminating all sources of standing water that can support mosquito breeding and applying insect repellent containing DEET," said California Public Health Officer Mark Horton, MD, MSPH, in a California Department of Health Services news release.

California experienced almost 300 cases of human West Nile virus in 2006, including seven deaths. This year, the first two U.S. cases of human West Nile virus were confirmed in Mississippi in April, reported the Mississippi Department of Health. In 2006, a total of 4,261 cases of West Nile virus were detected nationwide, according to the Centers for Disease Control and Prevention, including 174 deaths. The disease was most prevalent in Idaho, where there were almost 1,000 human cases and 21 deaths.