Climate change is expanding the reach of insect-borne diseases. Las Vegas' exploding mosquito population offers a case study of what's to come.A record number of mosquitoes are testing positive for West Nile virus in and around Las Vegas amid a surge in the area's overall mosquito population.fever, headaches, vomiting and diarrheaSign up for NBC San Diego newsletters.
Health officials have also identified six pools in the Las Vegas area that tested positive for St. Louis encephalitis virus, a mosquito-borne disease that can cause fatal inflammation of the brain. Las Vegas’ mosquito surge has been giant: Last year, district health officials measured 6,000 mosquitos in traps across Clark County from April to June. This year, counts have already exceeded 24,000.