West Nile Virus (WNV) has spread rapidly across the United States and Canada since its arrival in North America in 1999.

It infects over 150 species of birds as well as mammals including squirrels, dogs, wolves, horses and mountain goats.

Different types of mosquitoes are responsible for risk of disease in humans. One type feeds on birds and transmits the virus to other birds, which creates a large reservoir of WNV infection that starts to build in early spring. Another type of mosquito feeds on both birds and humans and can transmit the virus to humans.

While mosquitoes represent the most common route for transmission of the disease to humans, WNV can also be spread through blood or organ donation, pregnancy, lactation, needle-stick injury and exposure to infected laboratory specimens.

Symptoms of WNV range from fever accompanied by malaise, headache, myalgia, rash, lymphadenopathy, eye pain, anorexia and vomiting lasting for three to six days, to severe meningo-encephalitis. Severe muscle weakness and flaccid paralysis have also been experienced.

A large part of preventing the transmission of WNV relies on the elimination of mosquito breeding sites and the use of personal protection.

Public education can promote personal protection, but further control measures, including the use of larvicides and adulticides, have also been used to reduce mosquito populations.

Larvicides are used in the spring and early summer to reduce the number of emerging mosquitoes. They are often in granular, pellet or teabag formulations and are placed in catch basins and standing water sites that are close enough to human populations to pose a risk.

Adulticides are used to kill adult mosquitoes and are applied from equipment mounted on aircraft or trucks. They are used as a final measure when other methods to reduce mosquito populations have failed.

Canadian Medical Journal May 27, 2003;168 (11)

Dr. Mercola's Comments:

The pesticides that are being used to fight the West Nile Virus are surely going to contribute to a number of other diseases. Spraying for mosquitoes is a major problem across the country. Pyrethrum insecticides, a type of insecticide being used to combat the virus, have been shown to cause birth defects in animal studies (Abstract). They may also interfere with the immune and endocrine systems and toxicology testing has shown other adverse chronic effects, including effects on the liver and thyroid. Releasing toxic chemicals into the environment can have devastating effects. The major tragedy of the West Nile Virus is not the virus itself--it has not spread to epidemic proportions like a number of other chronic diseases--but rather the damage that is being done to people and their young and unborn children through exposure to these toxic chemicals. Further, pesticides, including commonly used lawn care chemicals, are causing more bird deaths than the West Nile Virus. In one study on the West Nile Virus, more of the collected birds had died from pesticide poisoning than from the virus itself. The symptoms of pesticide poisoning in humans are similar to the rather vague symptoms of the West Nile Virus itself, which are inflammation of the brain, weakness and neuropathy (peripheral nerve damage), leading to symptoms such as numbness. These could be mistakenly diagnosed as West Nile Virus, therefore creating more cases and a call for more intense spraying of pesticides. Related Articles: Pesticides, NOT West Nile Virus, are the Leading Cause of Bird Deaths Pesticides Targeting West Nile-Carrying Mosquitoes May be a Thyroid Danger Blowing the Whistle on West Nile West Nile Virus - Does it Exist?