West Nile Virus
West Nile virus is a strain of encephalitis similar to Saint Louis encephalitis, which reached epidemic proportions in the 1950´s and 60´s. West Nile virus, like encephalitis, is transmitted by mosquitos. There are several species of mosquitos that have been identified as vectors for West Nile, and more species are constantly being identified. One of the most common species, Culex pipiens or house mosquito, is a carrier as is the Tiger mosquito. These two species are common in and around residential areas which makes the disease that much more dangerous.
West Nile virus was first isolated in 1937 in a woman´s blood in the West Nile province of Uganda. Since then there have been outbreaks of epidemic proportions in Israel in the 50´s, France in the 60´s, thousands of cases in South Africa in the 70´s, and found in New York City in 1999. As of December 2002 there are 3,775 reported cases in the United States.It is not known how West Nile arrived in New York, but speculation ranges from an increase of human world travel to terrorist attempts at biological warfare. These speculations were prior to 9/11 and the anthrax threats. We still do not know how West Nile arrived but the latter is a more viable possibility then it was in 1999.
2002 brought 216 fatalities throughout the United States and 3,775 reported cases. The fatalities were nearly all elderly. Most people who become infected with the virus will have either no symptoms or mild ones, which indicates reported case numbers are much lower than actual cases. Most people who are infected with the virus will not have any type of illness. It is estimated that 20% of the people who become infected will develop fever: mild symptoms, including fever, headache, and body aches, occasionally with a skin rash on the trunk of the body and swollen lymph glands.The symptoms of severe infection include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis. It is estimated that 1 in 150 persons infected with this virus will develop a more severe form of disease. (From the C.D.C. website)The speed of the spread of this disease across country is attributed to wild and domestic birds. They are the most common vertebrae host for the disease thus making it extremely mobile. Crows, blue jays, pigeons, chickens, and hawks are among those carriers of the virus which once bitten and infected, cross state lines and are bitten by a local mosquito which in turn bites a local bird etc. The point is, movement is rapid and quarantine is next to impossible.
In an attempt to put a stop to the virus in the early stages resulted in mass fogging in New York City in 1999. It did little to stop the spread of the virus but caused an uproar among the human population. These treatments were done with the blessing of both the E.P.A. as well as the C.D.C. From what information I have pieced together about 70% of the population was in favor of the treatment and thirty adamantly opposed. Those in opposition were substantially more verbal. New York City was sued by a variety of environmental groups claiming the city was illegally spraying pesticides and contaminating water. ( I can only assume these groups never bothered to actually look at the Hudson River or other water bodies in the city.) As of December 3, 2002, a federal judge dismissed the lawsuit and ruled in favor of the New York City.Horses are also affected by the disease. As of June 2002 there is an effective vaccination for horses. There is also an approved larvicide that can be used in horse troughs. The larvicide is called Pre-Strike and is Altosid in a granular form. The vaccination is expensive and has to be applied by a veterinarian.What can be done for people? The states and counties that do not have a mosquito commission are rapidly getting one. Surveillance will increase. Mosquito control will become more prevalent especially with an increase of larviciding. The C.D.C. recommends that you try to avoid getting bit by avoiding heavily infested areas, using a repellent when you go outside, staying inside at peak mosquito times (dawn and dusk) and most importantly limit the number of places available for mosquitoes to lay their eggs by eliminating standing water sources.
You can find more great information and resources like this on the ScaPest web site http://www.scapest.com
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