West Nile Virus-Environmental Health & Safety - Carnegie Mellon University

West Nile Virus

Warm, damp weather often results in a large hatch of mosquitoes. Along with the mosquitoes we usually see an increase in the number of mosquito-borne illnesses, such as West Nile Virus. It is important that you know how to protect yourself.

First, you should know that few who become infected will  develop symptoms.  Some may show minor flu-like symptoms, but only in rare cases will the infection result in severe illness.  Those who are susceptible to severe cases, usually the elderly or those with depressed immune symptoms, can develop West Nile encephalitis, a potentially fatal brain inflammation.  Less than 1% of those infected will develop severe illness, however, and fewer still will die.  Also, those who are infected are believed to develop a lifelong immunity.

The virus is not spread from human to human, although there is rising suspicion that it could spread through organ transplants.  It is not spread by contacting dead birds, either, as many fear.  In the past we were asked to gather dead birds for the Board of Health, but that was only to determine if the virus had reached our area.

To avoid mosquito bites, stay indoors at dawn and dusk when mosquito activity peaks.  When outside, wear long sleeved shirts and long pants, and apply an insect repellent containing at least 35% DEET.  According to a study reported in the July 4, 2002, edition of the New England Journal of Medicine, “Only products containing DEET are dependable for long-lasting protection after a single application.”  The study also noted that when label directions are followed, DEET will not pose unreasonable risks or adverse effects to humans, so there is no reason to be afraid to use it.  DEET works by disrupting the ability of biting insects to detect the source of carbon dioxide—the gas naturally given off by our skin and in our breath— which is what attracts mosquitoes to us.  In other words, it doesn’t kill the insects—it just makes it impossible for them to locate their prey.

To reduce exposure, repair broken window screens, keep doors and windows closed, and eliminate any standing water sources.  Puddles, tires, or even lamp posts can contain standing water, perfect breeding grounds for mosquitoes.  Be watchful for these places and eliminate them. 

By following these simple precautions, and by knowing the truth about West Nile Virus, you can protect yourself and eliminate a lot of worry.