GOOSE CREEK, S.C. (AP) — Some mosquitoes captured at the Charleston Naval Weapons Station in South Carolina have tested positive for the West Nile virus.

Officials at Joint Base Charleston announced Monday that tests confirmed some recent samples were positive. No cases of the illness in humans have been reported.

The state Department of Health and Environmental Control, says 75 percent of people who contract West Nile suffer no symptoms.

In about 25 percent of cases, health officials say, patients may suffer mild illness with fever and aches. Less than 1 percent of those who contract the virus suffer a severe form of encephalitis that, in a few cases mostly among the elderly, can cause death.

The tests on the mosquitoes were performed at the U.S. Air Force School of Aerospace Medicine in Ohio.