WEST NILE VIRUS

Overview

The West Nile virus (WNV) is most often spread to humans from the bite of an infected mosquito. The WNV normally cycles between mosquitoes and birds. However, people may also be infected if they are bitten by a WNV-infected mosquito. Most cases of WNV are probably not acquired in the workplace but there are some workers at risk of WNV infection. Outdoor workers are at risk of WNV infection from the bite of an infected mosquito. 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.

Workers at risk of exposure to WNV include those working outdoors when mosquitoes are biting. Outdoor workers at risk include farmers, foresters, landscapers, groundskeepers and gardeners, painters, roofers, pavers, construction workers, laborers, mechanics, and other outdoor workers. Entomologists and other field workers are also at risk while conducting surveillance and other research outdoors.

Although WNV is most often transmitted by the bite of infected mosquitoes, the virus can also be transmitted through contact with infected animals, their blood, or other tissues. Thus laboratory, field, and clinical workers who handle tissues or fluids infected with WNV or who perform necropsies are at risk of WNV exposure.

Workers at risk should receive training that describes and reinforces the potential occupational hazards and risks of WNV exposure and infection. The importance of timely reporting of all injuries and illnesses of suspected occupational origin 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.

CDC Resources

CDC Interim Guidance for States Conducting Avian Mortality Surveillance for West Nile Virus and/or Highly Pathogenic H5N1 Avian Influenza VirusPDF only [PDF - 38 KB]

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.

Other U.S. Government Resources

Occupational Safety and Health Administration, Workplace Precautions Against West Nile Virus

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

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

National Library of Medicine, MedlinePlus West Nile Virus Site

Related NIOSH Publications

NIOSH Brochure: Recommendations for Protecting Outdoor Workers from West Nile Virus Exposure
DHHS (NIOSH) Publication No. 2005-155

NIOSH Brochure: Recommendations for Protecting Laboratory, Field and Clinical Workers from West Nile Virus Exposure
DHHS (NIOSH) Publication No. 2006-115

NIOSH Alert: Preventing Needlestick Injuries In Health Care Settings
DHHS (NIOSH) Pub No. 2000-108 November 1999

NIOSH Brochure: How to Protect Yourself From Needlestick Injuries
DHHS (NIOSH) Pub No. 2000-135

NIOSH Alert: Preventing Allergic Reactions to Natural Rubber Latex in the Workplace
DHHS(NIOSH) Pub No. 97-135 June 1997

Working in Hot Environments, DHHS (NIOSH) Publication No. 86-112