The Dangers of West Nile Virus – Symptoms & Treatment Tips

First reports of the West Nile virus rearing its ugly head in the U.S. were in 1999. In New York 62 contaminations and 7 deaths were confirmed.

Since then the virus has caused hundreds of deaths. The CDC not only reports thousands of cases of West Nile virus throughout the US but also Dengue Fever is taking its toll. Malaria outbreaks are still scarce in the US but the mosquito is wreaking havoc as it is.

In 2008 alone, the CDC reported 1,356 cases of West Nile throughout the U.S. and 44 deaths. In 2009 and 2010, outbreaks of dengue fever were reported in the U.S.

What exactly is West Nile Virus?

West Nile Virus is caused in humans by being bitten by an infected mosquito and symptoms can range from being completely non-existent, to cold and flu like, to brain inflammation and death.

It’s been seen in Europe, Africa, Australia and West Asia and made its first appearance in the US in 1999 and infection rates are steadily spreading.

It affects animals as well as humans, and so farmers need to take preventative steps for not only themselves and their family, but their livestock too.

It’s important to be armed with the knowledge of what West Nile Virus is, the symptoms, how to treat it and how to prevent it.

West Nile Virus in the US

The CDC estimates that over 3 million people in the US have been infected by the West Nile Virus, although most of them wouldn’t have even known, as the majority of cases don’t exhibit any symptoms.

The virus was first discovered in the West Nile region of Uganda in 1937 made its first appearance in the US when it appeared in the state of New York in 1999, likely carried by an infected mosquito that found its way onto a plane or cargo ship.

In 2014 over two thousand cases of West Nile virus were reported to the CDC, with human infections being reported in forty seven states, with eighty four fatalities.

While this is not as serious as infection rates in some previous years, with over nine thousand cases being reported in 2003 and a huge two hundred and sixty four fatalities, the virus is still highly infectious and prevention and understanding of the West Nile Virus are crucial.

interactive map West Nile incidences in the US
click the image for an interactive map (credit USGS)

How weather and climate increase your risks

While the CDC is not necessarily noticing an increase in cases over the last few years, outbreaks of West Nile Virus in the US are heavily dependent on the weather and climate each year.

A milder winter will often mean a more severe outbreak in the summer. Regions with weather conditions that a little kinder to mosquitoes tend to have more severe outbreaks, with Dallas being the city that has historically been hit the hardest by West Nile Virus.

Transmission: how do you get infected?

So far, the only known way to contract West Nile Virus for both humans and livestock is to be bitten by an infected mosquito.

No human-to-human, livestock-to-human, or human-to-livestock transmissions have been reported to date.

West Nile Virus Symptoms

Most people who become infected with West Nile Virus, an estimated 70-80% won’t even know that they have it, and experience no symptoms at all.

  • Around 20% of infected people may be experience ‘West Nile Fever’ which is characterized by cold and flu like symptoms, vomiting, diarrhea or a rash.


While most people with West Nile Fever will recover in a week or so they may remain fatigued and weakened for as long as several months.

Less than 1% of people will experience severe neurological symptoms, known as West Nile Neuroinvasive Disease. 20% of these severe cases result in death.

Symptoms of West Nile Neuroinvasive Disease include:

  • Encephalitis(a rare and acute brain infection) is the most common symptom of West Nile Neuroinvasive Disease and is characterized by fever, headaches, altered mental status, paralysis and muscle weakness
  • Meningitis ( inflammation of the protective membranes covering the brain ) which is normally diagnosed when the patient is experiencing a fever, headache and stiff neck and is characterized by the swelling of membranes covering the brain and spinal cord.
  • Poliomyelitis, (polio-like syndrome) characterized by sudden asymmetrical paralysis, weakness or loss of sensation.
  • Severe non-neurological symptoms of West Nile Virus which are again, present in less than 1% of cases, can include kidney disease, hepatitis, cardiac dysrhythmia, pancreatitis and myocarditis.


While it’s important not to panic and remember that most cases of West Nile Virus go completely unnoticed with no symptoms at that the mortality rate for West Nile Virus is far less than 1%, if you or anyone in your household is experiencing severe symptoms, it’s important to seek medical help.


In most cases where West Nile Virus is exhibiting minor symptoms (rash, headaches, etc) in an infected person, over-the-counter painkillers and bed rest are sufficient treatments.

In severe cases, patients may need to be hospitalized in order to receive some treatments and so that their condition can continue to be monitored.

How to prevent getting infected

No vaccine or specific anti-viral treatments exist for humans at this stage, although several have been developed for horses. It’s unlikely that a vaccine will be developed in the near future, as outbreaks are hard to predict and testing the vaccine would be difficult and definitely not cost-effective.

If a person has been infected once, even unknowingly, it’s believed that they’ll be immune from later infection.

While there is a test to see if you are immune to West Nile Virus, it’s very unreliable, so unless you are positive you’ve had West Nile Virus before, it’s best to assume you’re not protected and to take preventative measures.

These include:

  • Apply insect repellent and if wearing sunscreen as well, be sure to apply the repellent after the sunscreen.
  • To protect infants, use a carrier draped with mosquito netting
  • Wear long sleeves and pants when possible and spray insect repellent over the top of clothes.
  • Use insecticides around and inside your property when possible. If it’s not possible to keep mosquitos out of your home, drape mosquito netting over your bed at night. Despite abundant reviews praising natural repellents, DEET is still the most efficient, and thus your safest option. Picaridin is a good second repellent.  Be cautious with ‘DEET-free’ products.
  • Make your yard less attractive to mosquitoes. You spend most time at home. Especially if your yard is a breeding ground you will be overrun by the sickness causing bugs.
  • Stay informed, be on the lookout for new prevention methods, keep informed about outbreaks.



Mayoclinic, West Nile Definition.
Pennsylvania’s West Nile Control Program.
NPR West Nile on the Rise.

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