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West Nile Virus

There has been a huge increase in the number of reported West Nile Virus infections across the United States since 1999.  

It was first detected in 1999 in New York and then in Pennsylvania in 2000. There have been reports of more than 35,000 cases of West Nile Virus infections in humans in over 45 US states between 1999 and 2012. 

Most cases occur primarily in the mid summer or early fall, although mosquito season is usually April - October. 

The image below illustrates where human cases of West Nile Virus were reported in the United States during 2012. 

West Nile Virus activity in the United States during 2012

Image Source: United States Centers for Disease Control and Prevention

Transmission of the West Nile Virus

The transmission of West Nile Virus is primarily through the bite of an infected female mosquito, as only the females feed on blood. The virus is most commonly transmitted by Culex pipiens, Culex tarsalis and Culex quinquefasciatus in the United States.

The West Nile Virus not only infects humans, but also birds and mosquitoes. Bird species like pigeons and starlings are the most commonly infected animals that serve as hosts of this virus.

West Nile Virus Symptoms

The majority of infections in humans do not cause any symptoms. Where symptoms do occur, the incubation period is typically between 2 and 15 days.

West Nile Virus symptoms may include:

  • anorexia
  • fatigue
  • fever
  • headaches
  • muscle pain or aches
  • nausea
  • rashes
  • vomiting

The elderly, the very young and those with pre-existing medical conditions that affect immunosuppression, e.g. HIV infection, are most susceptible to contracting this virus and other mosquito-borne diseases

The image below illustrates the incidence rates by county of West Nile Virus in the United States during 2012. 

West Nile Virus incidence in the United States during 2012

Image Source: United States Centers for Disease Control and Prevention

There is currently no vaccine available against West Nile Virus infection.

Preventing the spread of West Nile Virus

The best way of preventing and reducing the rates of infection in residential and commercial areas are via mosquito control measures such as the elimination of mosquito breeding sites (standing pools of water, sides of water-filled containers, moist soil in flood-prone areas, etc) by source reduction and habitat modification, barrier treatments and mosquito larviciding. An empty container that can hold as little as a cup or more of water can be used as a breeding ground by mosquitoes. Without water, mosquito eggs cannot hatch.

To protect yourself against mosquito bites you should avoid areas where mosquitoes are more likely to congregate, like areas with dense vegetation - especially between dusk and dawn - as well as ensure that you use a mosquito repellent.

Professional Mosquito Control

Ehrlich Pest Control offers a range of affordable and efficient mosquito control solutions to both residential and commercial customers. Please call us now on or contact your nearest local office.

We provide season-long mosquito control by creating a mosquito-free barrier around your property and by targeting adult mosquitoes where they rest using conventional or all-natural materials.

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