Two new human cases of West Nile virus were reported in San Bernardino county Wednesday.
The latest reports bring the county's total to three this year, and just a day after a second human case of the virus was reported in neighboring Riverside county.
The Centers for Disease Control and Prevention says the number of cases around the country are up 25 percent in just the past week alone.
87 people have died from the infection this year nationwide.
The hardest hit states are Texas, South Dakota, Mississippi, Oklahoma, Louisiana and Michigan.
West Nile Virus is transmitted through the bite of an infected mosquito that has fed on an infected bird.
San Bernardino County's Department of Public Health says signs and symptoms may include fever, body aches, rash, nausea, vomiting and headache.
Most people infected with the virus have no symptoms.
But some may develop severe symptoms which can lead to meningitis or encephalitis.
The public should takes appropriate precautionary measures to protect themselves against mosquitoes.
People over 50 years old should be especially cautious, as they are more likely to develop serious illness if they contract the virus.
The following precautions can help keep you safer.
1) Avoid spending time outside when mosquitoes are most active at dawn and dusk.
2) Wear shoes, socks, long pants and long-sleeved shirts that are loose fitting and light colored.
3) Remove or drain all standing water around your property where mosquitoes lay eggs such as birdbaths, ponds, old tires, buckets, clogged gutters or puddles from leaky sprinklers.
4) Apply insect repellent containing DEET. When using DEET, be sure to read and follow the label instructions.
5) Make sure doors and windows have tight-fitting screens. Repair or replace screens that have tears or holes to prevent mosquitoes from entering the home.
San Bernardino county encourages the public to participate in the West Nile Virus surveillance program by reporting dead birds to the State West Nile Virus toll-free hotline at (877) WNV - BIRD or on-line at www.westnile.ca.gov.