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Carrington College Blog

West Nile Virus Spreads in the United States

July 15, 2014

West Nile has become common in the US.Since the disease entered the country in 1999, West Nile virus has been a regular summer concern for those in the United States. The flavivirus, which is indigenous to Africa, Asia, Europe and Australia, is believed to have entered the U.S by an infected traveler or animal. Reports of West Nile are generally found in birds or mosquitos, but the disease can be found in humans or horses as well. Though only a minute number of cases of West Nile virus result in serious sickness – and, in rare cases, death – in humans it is important to prevent the spread of West Nile virus in the hot summer months when mosquitoes are most prevalent. In the summer of 2014, the virus has been documented in a total of 28 states, including New York, Nebraska, California, Arizona, Michigan, Ohio, Louisiana, Tennessee, Mississippi and Texas, according to the Centers for Disease Control.Though human infections have not been found in all of the states, non-human West Nile activity has become widespread across the country, not limited to any particular geographical area.  

What is West Nile Virus?

West Nile Virus (WNV) is an infectious disease most commonly spread to humans by mosquitoes. The virus has a transmission cycle between mosquitoes and birds, therefore the disease is often more prevalent in areas in which birds migrate. In North America there are four major migratory routes for birds: the Pacific, the Central, the Mississippi, and the Atlantic.Mosquitoes get the virus from infected birds and spread the disease to humans and horses. When a horse or human gets the disease, they are considered a dead-end host as they cannot spread the disease by touch or proximity. However, a very small number of WNV cases have been caused by blood transfusions or organ donations.

Though the disease has only been present in the U.S. for a decade and a half, the first human case of WNV was in the West Nile region of Uganda in 1937.3 Infected birds and sometimes horses tend to serve as harbingers that WNV is present in a specific geographical area. It is possible to report dead birds, but many states have stopped testing birds for West Nile as the virus has become well established throughout the continental United States. There is no evidence that handling infected dead birds can result in infection.4 However,  it is good practice to wear gloves when handling any dead animal.

Symptoms of West Nile 

Only around 20 percent of humans exposed to West Nile virus will ever exhibit symptoms.Those that do have symptoms generally experience what is commonly referred to as West Nile fever, an aguing, febrile condition. Symptoms of West Nile fever include headaches, body ache, back pain, fatigue and fever, as well as occasional cases of eye pain, skin rash and swollen lymph glands.There is no current cure for West Nile virus, so those experiencing symptoms are advised to take ibuprofen and simply wait it out.7 However, fatigue can last for weeks after the other symptoms of the infection have subsided.

In less than one percent of all human cases, West Nile virus can cause a serious neurological infection.8 This can result in inflammation of the spinal chord or brain, which can be potentially life threatening. If experiencing symptoms such as muscle twitching, a lack of coordination, convulsions, a stiff neck, severe headache or extreme muscle weakness, see a doctor immediately.Severe cases of West Nile virus generally require hospitalization.

Prevention Methods

It is important to remember that not all mosquito bites result in West Nile virus. However, there are a number of precautions people can take when enjoying the outdoors during the summer months. Here are several tips for mitigating your chances of becoming infected with West Nile virus:

  • Mosquitoes are most active around dawn and dusk, so whenever possible limit your time outdoors during these times of day.
  • Use a spray bug repellent to ward off mosquitoes. Spray yourself regularly before going outdoors, especially when doing physically demanding activities such as gardening or hiking. Apply bug repellent to clothes as well as skin to ensure you are evenly protected.
  • Keep doors closed and make sure window and door screens are patched to prevent mosquitoes from entering your home.
  • Make sure there is no standing water around your home. Empty flowerpots and trash cans collect rain water that can attract mosquitoes. Empty such receptacles to keep away bugs. 
  • Regularly change the water in birdbaths and other containers.
  • At the beginning of the summer, make sure roof gutters and drains around your house are unclogged to ensure there is no standing water after it rains.
  • Cut your grass and weed wack regularly to eliminate spots for mosquitoes to hide out during the day.9

1“West Nile Virus Activity by State – United States, 2014 (as of July 15, 2014)” by Center for Disease Control. July 15, 2014.

2“West Nile Virus Human Infections Now in Seven States” by Beth Balen. Guardian Liberty Voice. July 15, 2014.

3“West Nile Virus Human Infections Now in Seven States” by Beth Balen. Guardian Liberty Voice. July 15, 2014.

4“FAQ: West Nile Virus & Dead Birds” by Center for Disease Control.

5“Symptoms” by Mayo Clinic Staff.

6“Symptoms” by Mayo Clinic Staff.

7“West Nile virus is making a comeback” by Jessica Firger. CBS News. July 11, 2014.

8“Symptoms” by Mayo Clinic Staff.

9“County alerts residents of confirmed West Nile virus” by Wasau Daily Herald. July 11, 2014.