Minnesota has recorded its first death from West Nile virus this summer.
Department of Health epidemiologist Dave Neitzel said an elderly man developed a fatal case of encephalitis last month after being bitten by an infected mosquito.
"This is a patient that lived in the more open, agricultural part of Minnesota, which is typically our highest risk area for West Nile virus. The mosquito that does most of the virus transmission is a mosquito that really likes that open farm country," Neitzel said.
So far there have been 16 confirmed cases of the infection. In addition, two blood donors also had evidence of the virus in their blood.
Neitzel said people who are sick now were likely infected following a stretch of warmer weather in July, when the heat amplified the virus in the mosquito population.
"The virus grows more quickly in real hot conditions - grows more quickly both in mosquitoes and in birds," Neitzel explained. "So cooler weather is not only nice for us to get out and walk around a little bit, but it slows down the growth of the virus."
Neitzel said hot and dry years tend to produce the most West Nile cases in humans.
Even though August is typically the peak month for transmission, mosquitoes can still infect people well into the fall if the weather is mild.
Since tracking of West Nile began in 2002, Minnesota has recorded 17 deaths from the virus.