SAN DIEGO -- A San Diego County boy has contracted West Nile virus -- the county's first human case this year -- although the child was infected in another state, health officials said Friday.

The boy apparently contracted the disease while vacationing in Idaho, according to a statement released by the county Health and Human Services Agency.

"The child was hospitalized but has been discharged," San Diego County Public Health Officer Nancy Bowen said.

Four dead birds have tested positive for West Nile virus in San Diego County so far this year, but until now, there had been no human cases reported, according to Leslie Ridgeway of the county health and human services agency.

The public can protect against the virus by limiting outdoor activity at dawn and dusk, wearing long sleeves and pants, using insect repellent with DEET or Picaridin, removing standing water from the perimeter of homes and installing tight-fitting screens in windows and doors.