These are the highest risk areas for West Nile virus in Minnesota

Late summer and early fall are high-risk times for the virus.

The risk of getting West Nile virus is higher than ever this time of year.

That's a reminder from Minnesota Department of Health: late summer and early fall are high-risk times for West Nile virus infections, because infected mosquito populations are at their highest levels.

The department says areas with open farm land and prairie are the most at-risk parts of Minnesota, because they provide the best habitat for Culex tarsalis, the mosquito that carries the virus. 

The mosquitos like to breed in semi-permanent wetlands and stagnant drainage ditches.

The map below shows western and central Minnesota have the most at risk counties.

Traverse County is the most at-risk area of the state, with 30.90 average cases per 100,000 between 2002-2016. That's followed by Big Stone County, with 24.06 cases.

People most at risk

Farmers, outdoor workers, and outdoor enthusiasts are most at risk of being bitten by an infected mosquito, simply because they spend the most time outside, the Minnesota Department of Health says.

Most reports of West Nile virus cases tend to be in men between 60 to 65 years old. The department says that could be because older men spend more time outdoors. 

Men actually have more reported cases of West Nile virus than women for all age groups, except for those under age 5. 

Middle-aged to older adults see the most cases in general, which can be very dangerous, because the department says older adults are also more likely to develop severe symptoms from the virus, like encephalitis (brain swelling).

People who get sick usually start showing flu-like symptoms 3-15 days after being bitten. They may also develop a rash that lasts a few days. In rare cases, the virus can cause muscle weakness, stiff neck, disorientation, tremors, convulsions, paralysis, coma, or even death.

A human West Nile vaccine is still in development, the department says (there is one available for horses).

West Nile virus in Minnesota

West Nile virus cases were first found in Minnesota in 2002, the department says. The worst year so far was 2003, which saw 148 cases.

The number of cases varies each year, and is influenced by environmental factors like temperature and precipitation. Warm, dry conditions are ideal for the mosquito to breed and the virus to reproduce.

As of Sept. 5, 13 Minnesotans had been infected with the virus this year, according to this chart from the Centers for Disease Control and Prevention (CDC). 

There have been a total of 526 cases across the country this year. 

Prevent mosquito bites

The state Department of Health offers these tips to prevent getting bitten by infected mosquitoes:

  • Avoid outdoor activity at dusk and dawn.
  • Wear long-sleeved shirts and long pants.
  • Install or repair screens on windows and doors.
  • Remove small pools of standing water from around your home.
  • Use a bug repellent with 30 percent DEET.

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