Last year, California experienced a record number of deaths due to the mosquito-borne West Nile virus. Health officials believe the spike in deaths is linked to the ongoing severe drought the state is experiencing.
There were 31 people who died from West Nile virus in 2014 in California, according to the state's Department of Public Health. This is the highest number of cases since the state started collecting information about West Nile in 2003.
The drought has lowered the level of water in reservoirs, lakes, rivers, and streams in the state, in some cases to historically low levels. West Nile virus is spread through birds and mosquitoes. As water sources shrink, birds and mosquitoes come into closer contact with each other and the mosquitoes pick the virus up from birds. An infected mosquito can then transmit the virus to people and animals through a bite.
The drought is also causing smaller bodies of water and streams to stagnate, and mosquitoes breed best in stagnant water.
Although the number of deaths due to West Nile in 2014 was a record for California, the number of overall cases was not. There were 801 residents of the state who tested positive for West Nile, but the record was 880, set several years ago. Orange County, in Southern California, had 263 cases, the highest in the state.
West Nile virus causes flu-like symptoms. Most people who are infected with the virus do not get seriously ill, but older people and those with other underlying illnesses have a greater risk of developing complications. A very small percentage of people who become infected with West Nile can develop encephalitis or meningitis.
Residents of California have been told to use insect repellant and wear protective clothing when outside especially at dawn and dusk to reduce the risk of being bitten by mosquitoes. They have also been told to drain any stagnant pools of water near their homes.