West Nile virus cases spike after 7 Harris County resident infected, 520 mosquito samples test positive KPRC Click2Houston7 Harris Co. residents infected with West Nile Virus, county health officials say KTRK-TVFirst West Nile virus human case reported in Dallas: DCHHS NBC DFW7 cases of West Nile virus confirmed in Harris County residents; over 500 positive mosquito samples KHOU.comSeven people test positive for West Nile, officials warn of spike after Beryl Houston Chronicle