BOISE, Idaho -

Gem County in southwestern Idaho is the latest place in the state to report mosquitoes that tested positive for carrying the West Nile virus.
   
Tuesday's announcement from public health department officials follows a report that a Twin Falls woman contracted the potentially dangerous illness.
   
That woman, in her 40s, has recovered. She was the first human case reported this year.
   
Officials aren't sure where she contracted the virus.
   
Along with Gem County, West Nile-carrying mosquitoes have been documented in Ada, Canyon and Payette counties this year.
   
Idaho led the nation in West Nile cases in 2006, with 1,000 infections reported and 23 deaths. Last year, there were three reported cases in humans, and no deaths.
   
The illness is of particular concern to older people or those with weakened immune systems.