One late summer day, fresh out of residency and seeing patients for the first time as a full-fledged family physician, I examined a young man who had a fever, fatigue, and a bad headache. Considering the time of year, influenza was low on the list of possibilities, and COVID-19 did not yet exist. After a physical exam and listening to his story, I ordered some tests, which resulted in a diagnosis of West Nile virus.

Now that we are entering the later half of the summer, the weather and environment are prime for West Nile virus. When the weather becomes hotter and drier, the mosquito species Culex thrives and has the potential to harbor West Nile virus in its saliva.

The first reported case of West Nile virus in the United States was in 1999. Now, it’s here to stay. There is no vaccine for West Nile virus for humans. The treatment is largely supportive, rest, fluids, and time.

Thankfully, most people who become infected with West Nile virus have mild or no symptoms. About one in five of those infected develop a fever, headache, rash, muscle aches, joint pains, vomiting, or diarrhea. About one in 150 may develop a severe case that affects the central nervous system, resulting in encephalitis which is inflammation of the brain, or meningitis known to cause inflammation of the membranes around the brain and spinal cord. Some of those cases can be fatal, which equates to an average of 130 deaths in the United States from West Nile virus each year. 

You cannot get West Nile virus from another person. The key to prevention is to avoid getting bitten by a mosquito. This late summer and early fall, remember the mosquito repellent, avoid going outside at dawn or dusk, consider wearing pants and long-sleeved shirts, and consider treating your clothes with permethrin which can kill or repel mosquitoes. Avoid having areas or containers outside that can collect water and create spaces for mosquitoes to lay eggs. 

It took a couple of weeks, but thankfully my patient fully recovered. Nowadays, if it is late summer or early fall, and someone has a fever, headache, and fatigue, there is a good chance it is COVID-19. However, one must remember other causes, and West Nile virus is certainly a possibility. 

Richard P. Holm, MD passed away in March 2020 after a battle with pancreatic cancer. He is founder of The Prairie Doc®. For free and easy access to the entire Prairie Doc® ® library, visit wwww.prairiedoc.org and follow Prairie Doc® on Facebook. Andrew Ellsworth, M.D. is part of The Prairie Doc® team of physicians and currently practices family medicine in Brookings, South Dakota.