SAN DIEGO -- A 12-year-old Rancho Penasquitos girl is the latest known, local victim of West Nile Virus, the San Diego County Health and Human Services Agency announced Tuesday.

The child did not have to be hospitalized and is improving, according to the agency.

There have been a total of 31 victims in the county.

This 12-year-old is the 29th person to acquire WNV locally. One other was infected while traveling and and another one was diagnosed after donating blood, but displayed no symptoms.

Last year, 15 people contracted the virus.

The county has also discovered 535 dead birds, 15 sentinel chickens that tested positive for the virus, five infected horses -- of which four died, and 39 mosquito batches that tested positive.

Most people infected with West Nile virus do not show symptoms or become seriously ill.

Those who do suffer from headaches, fever, nausea, fatigue, skin rash or swollen glands.

About one in 150 cases turn into more serious neurological illnesses such as meningitis, encephalitis or myelitis.

The county recommends wearing mosquito repellent when outdoors at dawn or dusk, not sleeping outside unprotected by long sleeves and pants, ensuring window screens are fit properly and have no holes, checking your property regularly for mosquito breeding sources and reporting unattended pools that have turned green.