West Nile Virus
Mosquitos role in the west nile virus
The West Nile virus (WNV) is most often spread to humans from the bite of an infected mosquito. The virus can also be transmitted in other ways–through organ transplants, blood transfusions, breast milk, and from mother to fetus–but the risk of such transmission is very low. WNV was first reported in the United States in 1999, and occupational exposures have been documented. Today, the virus is reported throughout the continental United States.
Testing for WNV infection is available, however, no vaccine is currently available to prevent WNV infection in humans. Most WNV infections occur from July through September.
Symptoms of West Nile Virus
About 80% of WNV cases have no symptoms. About 20% cause flu-like symptoms, including fever, fatigue, headache, and muscle or joint pain.
Fewer than 1% of humans infected with WNV become severely ill. Severe symptoms include high fever, stiff neck, disorientation, tremors, muscle weakness, and paralysis. Severely affected persons may develop encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes of the brain or spinal cord). Severe cases may be fatal.
Workers at the greatest risk of exposure to WNV include those working outdoors when mosquitoes are biting, including farmers, foresters, landscapers, groundskeepers and gardeners, painters, roofers, pavers, construction workers, laborers, mechanics, and other outdoor workers. In addition, laboratory, field, and clinical workers who handle tissues or fluids infected with WNV are at risk. People above age 50, and individuals who have had organ transplants or who have a compromised immune system also have a high risk of severe illness from WNV infection.
