West Nile season has been mostly unaffected by drought, but hot weather plays a factor

While populations of floodwater mosquitoes, which do not carry the virus, were down, the species of mosquito that carries the virus, Culex tarsalis, lays eggs in standing water and maintained average populations throughout the summer.

Al Schoepp, left, and Jason Klug spray a chemical barrier onto a tree line in 2020, north of Cass County Highway 20 to limit the spread of mosquitoes. Michael Vosburg / Forum Photo Editor
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GRAND FORKS -- This season of West Nile virus has been largely unaffected by the ongoing drought in the Upper Plains.

While populations of floodwater mosquitoes, which do not carry the virus, were down, the species of mosquito that carries the virus, Culex tarsalis, lays eggs in standing water and maintained average populations throughout the summer.

According to Amanda Bakken, North Dakota Department of Health West Nile virus surveillance coordinator, this year’s weather still may have led to an uptick in cases since last year.

“Research has shown in the past that milder winters and drought-like conditions with higher temperatures has increased West Nile virus activity for the proceeding summer,” said Bakken.

Bakken explained that higher temperatures mean more chances for mosquitoes to breed and accelerated egg development, which leads to higher populations of mosquitoes. Warmer spring temperatures can also impact bird migration patterns, bringing infected birds for mosquitoes to feed on to the area earlier.


The North Dakota Department of Health reported the state’s first West Nile virus-related death on Sept. 10. Officials from the Department of Health say the individual was a resident of southwest North Dakota over the age of 60.

This year, there have been 20 cases of West Nile virus reported in North Dakota. In Minnesota, there has been one reported case and in South Dakota, there have been 21 reported cases. South Dakota, which has historically had the highest rates of West Nile virus cases in the U.S., reported its first death on Aug. 31.

As of Sept. 7, there have been 210 cases and nine West Nile virus-related deaths across the United States. There are currently no vaccines or medications to prevent or treat the virus in humans, so according to the CDC, the best way to protect yourself is taking preventative measures against mosquito bites. Using insect repellant, wearing long sleeves and pants and limiting time outside around dusk and dawn can reduce the risk of being bit by an infected mosquito.

Because the mosquito that carries West Nile virus lays eggs in standing water, frequently emptying or covering buckets, tires, birdbaths and other water-holding items prevents mosquitoes from laying eggs.

According to the CDC, most people who contract West Nile virus never show symptoms. About one in five people infected show mild symptoms like a fever accompanied by headaches, body aches, joint pain and vomiting. One in 150 people develop severe illnesses that impact their nervous systems such as encephalitis (inflammation of the brain) and meningitis (inflammation of the membranes surrounding the brain and spinal cord).

People above the age of 60 or those with preexisting conditions are at the highest risk for developing severe illness. Recovering from a severe case of the virus can take weeks or months, and some damage to the central nervous system may be permanent.

Bakken says the most important thing to do if you have any West Nile virus symptoms is to get tested by a doctor. Because West Nile symptoms with many other common illnesses, it is impossible to know the best treatment plan without getting tested.

“This is the time of year where you’re in the West Nile virus season, you also are potentially in the Lyme disease season, which can have similar symptoms, and you’re going into flu season,” said Bakken. “There are all these other things that can be tested for that I think people are forgetting about because it's been ingrained in us now to think about COVID.”


Bakken also suggested staying up to date with West Nile virus information in their area. The North Dakota Department of Health also posts weekly reports of West Nile numbers in each county and statewide.

Ingrid Harbo joined the Grand Forks Herald in September 2021.

Harbo covers Grand Forks region news, and also writes about business in Grand Forks and the surrounding area.

Readers can reach Harbo at 701-780-1124 or Follow her on Twitter @ingridaharbo.
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