Grand Forks health officials are warning the public to protect themselves against mosquito bites after the first North Dakota case of West Nile virus was found Tuesday and the number of mosquitoes that can transmit the disease has risen.
The percentage of culex mosquitoes, the most common species to transmit the virus and one of the most common mosquitoes in the region, jumped from an average of 15 percent of total mosquitoes to 58 percent on Monday, said Todd Hanson, supervisor of Grand Forks Mosquito Control.
A crow had been found with the virus in Grand Forks on Monday, and test results came back positive Tuesday, but Hanson would not identify exactly where the bird had been found.
After a mosquito feeds on an infected bird, it can pick up the virus and transmit it to humans and other mammals as well as noninfected birds, according to the Grand Forks Health Department.
Most people infected with the West Nile virus, which can be fatal, do not develop symptoms.
Still, a mild illness with symptoms such as fever, headache, body aches and swollen lymph nodes can develop in some people one to two weeks after exposure, the health department said.