What is West Nile?

  • West Nile virus is a mosquito-borne virus that in rare cases can cause high fever, encephalitis (inflammation of the brain), meningitis (inflammation of the lining of the brain and spinal cord), paralysis, and even death.
  • Although the majority of people infected with West Nile virus will never get sick or will only develop a mild flu-like illness, a small number of infected people will develop more serious symptoms, which can be life-threatening.
  • West Nile virus first appeared in North America in 1999 and El Paso reported its first case of West Nile virus disease in 2003. Every year people in El Paso are hospitalized with West Nile virus disease.
  • People of any age can be infected with West Nile virus and get sick but people over the age of 50 and people with chronic conditions are at greatest risk of developing serious complications.
  • People cannot be vaccinated against West Nile and options for treatment of the disease are very limited.
  • Preventing mosquito bites by reducing the number of mosquitoes around your home and by covering exposed skin and wearing insect repellant while outdoors are the most effective methods of preventing West Nile.


Got Mosquitoes?

Are you itching for relief from mosquitoes? Contact the Code of Compliance Division of the City of El Paso Environmental Services Department at phone number 3-1-1. The Code of Compliance Division oversees the city’s vector control program, which combats mosquito breeding in El Paso County. The mosquito abatement efforts are intended to reduce the spread of West Nile Virus and other mosquito-borne infections.

See what is being done to control mosquitoes in your area by clicking on the map below:




  • People are infected with West Nile when they are bitten by a mosquito carrying the virus.
  • Not all mosquitoes can pass the West Nile virus to people, only those belonging to the genus Culex.  And of those Culex mosquitoes only a very small proportion are actively carrying the virus at a given time.
  • While humans, horses, and some other mammals can get sick when infected with West Nile, they are not the primary hosts for the virus. The Culex mosquitoes that carry West Nile actually prefer to bite birds. Many infected birds will develop high levels of virus in their blood and can carry the virus long distances. When a mosquito bites an infected bird it can pick up the virus and become infectious. It is this passage of the virus between mosquitoes and birds that is responsible for the long-term transmission of the disease.
  • People are at greatest risk of being bitten by mosquitoes and infected with West Nile virus during the summer and early fall. Taking appropriate measures for preventing mosquito bites is especially important during this time of year.
  • In El Paso it has been shown that living close to irrigation canals increases a person’s risk of getting West Nile virus disease. People living near irrigation canals should take extra care to prevent mosquito bites.
  • In a very small number of cases, West Nile virus has been spread through blood transfusions, organ transplants, and from mother to baby during pregnancy, delivery, or breastfeeding. It should be noted, however, that transmission through any of these alternate mechanisms is exceedingly rare. The U.S. blood supply is now screened for West Nile virus.   



  • Most people who get West Nile virus will never get sick or know they were ever infected! Between 70 and 80% of people will successfully fight off the virus without ever experiencing any symptoms.
  • About 20% of people that get infected will experience a mild form of the disease.
  • People who do get sick from West Nile usually will begin to show symptoms between 3 and 14 days after initial exposure to the virus.
  • In less than 1% of people who are infected with West Nile virus a very serious disease will develop. Symptoms of this serious form of West Nile may include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis.
  • About 10% of cases in which these serious complications develop are fatal.
  • People experiencing these severe symptoms need to seek immediate medical attention.


Preventing Mosquito Bites & West Nile:

  • The most effective way to prevent West Nile is to prevent mosquito bites while outside and to reduce the number of mosquitoes around your home.
  • Don't stop enjoying outdoor activities! Just learn some simple and effective prevention measures to reduce your risk of getting West Nile.
  • Mosquitoes are most active during dawn and dusk hours. If you know you will be outside during these hours, plan ahead and take appropriate measures to prevent mosquito bites.
  • Try to limit the amount of skin you have exposed while outside by wearing long-sleeved shirts and long pants.
  • Use insect repellant whenever you go outside!
  • Repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus, and para-menthane-diol are known to be effective at deterring mosquitoes.
  • Not all repellants are created equal: Repellants containing a high percentage of DEET are safe, effective, and provide long-lasting protection against mosquitoes.
  • Remember to apply repellant only to exposed skin and to avoid contact with your eyes, mouth, or any open cuts. Apply repellant sparingly around your ears.
  • You can use both sunscreen and insect repellant together. Just make sure to apply sunscreen first and the repellant second.
  • Most insect repellants can be used on children. However, always refer to the label instructions and never let young children apply their own repellant. When using on children, apply repellant to your own hands first and then put it on the child.
  • Reducing the number of areas where mosquitoes eggs and larvae can develop is the first step toward keeping your home and yard mosquito-free.
  • Try to empty standing water from containers such as flowerpots, gutters, pool covers, pet water dishes, birdbaths, or fountains at least once every week.
  • Items that can collect rainwater such as wheelbarrows, flowerpots, buckets, discarded tires, or hubcaps should be turned over or stored inside when not in use to prevent the accumulation of stagnant water.
  • Keep mosquitoes out of your home by installing and maintain window and door screens and by keeping doors closed, especially during dawn and dusk hours.


For Pet Owners:

  • West Nile virus is not known to cause illness in dogs or cats.
  • Most other mammals also will not get sick if exposed to West Nile virus.
  • Horses, like humans, can be infected with West Nile virus and rarely will develop a serious disease.
  • However, an effective vaccine against West Nile virus does exist for horses. Horse owners should consider getting their animals the appropriate vaccinations and booster shots prior to peak mosquito season.
  • Concerned pet owners should consult with their veterinarian if their pets are exhibiting any unusual symptoms.


West Nile Virus Interactive Map

See El Paso areas where West Nile virus disease has been reported since 2009 by clicking on the map below:


Dengue & Chikungunya Viruses:

  • In many parts of the American Tropics, mosquitoes can also transmit Dengue and Chikungunya viruses to people.
  • Infection with the Dengue virus can lead to Dengue Fever or Dengue Hemorrhagic Fever. People with Dengue Fever usually have a high fever, headache, joint and muscle pain, rash, and sometimes mild bleeding. Dengue Hemorrhagic Fever is more serious and can cause vomiting, severe abdominal pain, difficulty breathing, and sometimes death.
  • Chikungunya infection is not life threatening but can initially lead to fever, headache and muscle and joint pain. In some cases, severe joint and muscle pain can persist for many months.
  • Mosquitoes in El Paso do not currently carry Dengue or Chikungunya, however, there are species of mosquitoes capable of carrying these viruses in our area.
  • Currently the risk of getting infected with either of these viruses near El Paso is very small. However, in future years there could be local transmission of these viruses in the El Paso area.
  • The same measures for preventing West Nile can also be applied to Dengue & Chikungunya! Apply insect repellant, cover exposed skin, and don’t let mosquito eggs and larvae develop near your home.
  • Both Dengue & Chikungunya viruses are only able to infect humans and other primates. These viruses do not typically pose a risk to dogs, cats, and other pets.
  • Travelers to areas where Dengue & Chikungunya are transmitted should be aware of any mosquito bites and should watch for any symptoms for two weeks following their return home. If any symptoms develop, contact your doctor and inform them of your recent travel.


Want more information? Check out these fact sheets, links, and educational materials!

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