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The West Nile virus (WNV) is most often spread to people from the bite of an infected mosquito. The WNV normally cycles between mosquitoes and birds. However, people may be infected if they are bitten by a WNV-infected mosquito.

Outdoor workers are at risk of WNV infection from the bite of infected mosquitoes. Workers at risk include farmers, foresters, landscapers, groundskeepers and gardeners, painters, roofers, pavers, construction workers, laborers, mechanics, and other outdoor workers. Entomologists, wildlife biologists, and other field workers are also at risk while working outdoors.

mosquito biting finger

NIOSH Fast Facts Card

Fast Facts: Protecting Yourself from Ticks and Mosquitoes NIOSH Fast Facts Card: Protecting Yourself from Ticks and Mosquitoes (En Español) Print or order this free card for easy access to important safety information.

Laboratory, field, and clinical workers who perform necropsies of infected birds or handle WNV-infected tissues or fluids are also at risk of WNV infection if their skin is penetrated or cut. The virus can be transmitted through contact with the blood or other tissues of infected animals.

Workers at risk should receive training that describes and reinforces the potential occupational hazards and risks of WNV exposure and infection. The importance of the timely reporting of all workplace injuries and illnesses should be emphasized. A medical surveillance system should be in place which includes the reporting of symptoms consistent with WNV infection, laboratory incidents or accidents involving possible WNV exposures, and employee absenteeism.

NIOSH Publications

CDC Resources

CDC West Nile Virus

CDC Insect Repellent Use and Safety

BioSafety in Microbiological and Biomedical Laboratories (5th edition, 2009).

CDC [2002]. Laboratory-Acquired West Nile Virus Infections — United States, 2002. MMWR 51(50): 1133-1135.

CDC [2003]. West Nile Virus Infection Among Turkey Breeder Farm Workers --- Wisconsin, 2002. MMWR 52(42): 1017-1019.

CDC West Nile Virus in the United States: Guidelines for Surveillance, Prevention, and Control [PDF - 1.66 MB]

Other Resources

New York State Department of Health, West Nile Virus Fact Sheet for Outdoor Workers

U.S. Geological Survey (USGS) National Wildlife Health Center, West Nile Virus Site

USGS National Wildlife Health Center Guidelines for Handling Birds

National Institutes of Health, National Institute of Allergy and Infectious Diseases, West Nile Virus Site

National Library of Medicine, MedlinePlus West Nile Virus Site


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  • Page last reviewed: August 27, 2012
  • Page last updated: August 27, 2012 The U.S. Government's Official Web PortalDepartment of Health and Human Services
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