A mosquito pool sample collected from the 1200 block of Zion Road has tested positive for West Nile virus, Atlantic County officials say.The sample was collected July 29 and is the fourth positive sample in the county this year.Other positive samples were collected from the 300 block of Royal Avenue in Linwood, the 700 block of West Park Avenue in Pleasantville and the 600 block of Kingsley Avenue in Ventnor.