VALPARAISO | Health officials are urging residents to take precautions to protect themselves from mosquitoes after a mosquito pool in Porter County tested positive for the West Nile virus.

Keith Letta, Porter County health administrator, said the finding is nothing new for Porter County, where the virus has been found every year since 2001. He said the mosquito that carries the virus is more of a city mosquito than a country mosquito, and likes to live and breed in catch basins and drains.

West Nile virus is transmitted to humans by mosquitoes that have first bitten an infected bird. A person bitten by an infected mosquito may show symptoms three to 15 days after the bite.

The virus usually results in a mild illness known as West Nile fever, which can cause fever, headache, body aches, swollen lymph glands or a rash. However, a small number of individuals can develop a more severe form of the disease with encephalitis or meningitis and other neurological syndromes.

"In previous years, most human cases of West Nile virus were reported between mid-July and mid-September," said Gary Babcoke, Porter County health officer.

Residents are urged to take the following steps when they are outdoors:

-- Avoid being outdoors during prime mosquito biting times, dusk to dawn.

-- Apply insect repellent containing DEET, picaradin or oil of lemon eucalyptus to clothes and exposed skin.

-- Wear long--sleeved shirts and pants.

Residents can get rid of potential mosquito breeding grounds through the following steps:

-- Repairing failed septic systems.

-- Drilling holes in the bottom of recycling containers left outdoors.

-- Keeping grass cut short and shrubbery trimmed.

-- Disposing of old tires, cans, pots or other unused containers that can hold water.

-- Cleaning clogged roof gutters and drains.

-- Aerating ornamental pools or stocking them with predatory fish.