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Are Pesticides the Cure or the Cause for West Nile Virus?

petnews
June 16th, 2003, 01:06 AM
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