West Nile Virus

Introduction

West Nile Virus is, as its name implies, a virus. The virus is transmitted through the bite of the mosquito. The first reported human case was a Ugandan woman in 1937. Over time it has become prevalent in Africa, Asia, the Middle East and parts of Europe. In 1999, the first case(s) of West Nile Virus (WNV) were discovered in the New York City area and it has since spread across the United States. As of 2006, 43 species of mosquitoes have been identified as carriers of the disease. WNV is just one of the family of flaviviruses. Other members of the family are responsible for Yellow Fever, Japanese Encephalitis and Dengue Fever.

NWV primarily affects birds with crows being the most prominent avian host. Humans and other animals are considered "incidental" hosts. But, it is the high number of "incidental" hosts available and the large number of mosquito-carrier species that has caused the wide-spread transmission across the US. According to the CDC's 2008 report, WNV in humans has been identified in 44 of the lower 48 states with no cases (avian or human) reported for Alaska or Hawaii.^[1][2]

Prevention

• When outdoors, use insect repellent containing 35% DEET for adults and 10% DEET for children. Follow the directions on the package.
• Many mosquitoes are most active at dusk and dawn. Be sure to use insect repellent and wear long sleeves and pants at these times or consider staying indoors during these hours.
• Avoid wearing dark coloured clothing.
• Avoid wearing perfume/cologne and scented cosmetics.

Pre-Exposure Vaccines

NO pre or post-exposure vaccines are available.

Symptoms and Treatment

Symptoms

• Statistics have shown that out of every 150 people infected with WNV, 80% will develop no symptoms and recover from the disease on their own.
• Of the remaining 20%, 19.6% will suffer mild symptoms. These will manifest themselves as fever, head and body aches, vomiting, swollen lymph nodes, possible body rashes and will last for a few days.
• The remaining 0.4% (or 1 out of 150 people) will develop severe symptoms which include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness and paralysis. All (or most) of these symptoms occur when the virus has entered the spinal column (meningitis) and/or brain (encephalitis).^[3][1]

Treatment

At this time there are no specific treatments nor human vaccines for WNV. Those requiring medical attention will be treated symptomatically. Using preventative measures against mosquitoes is the best defense.