Rationale:

• Clothes that cover extremities can prevent mosquito bites.
• Standing water allows mosquito larvae to develop; small holes in screens can allow mosquitoes indoor access.
• DEET and permethrin repel mosquitoes.
• The peak biting times of Culex mosquitoes, the most common WNV vector, are before dawn and after dusk.
• Integrated mosquito control programs decrease mosquito populations and, therefore, transmission of WNV.

Evidence:

• A recent clinical review article stresses that covering extremities should decrease risk for mosquito exposure per expert recommendation (1).
• Mosquitoes in the home, mosquito bites, and standing water were associated with WNV infection in two case-control studies of 393 cases of WNV meningoencephalitis in Romania in 1996 (2)
• Classic work indicates that environmental monitoring and maintenance is associated with decreased arthropod-borne virus exposure (3).
• In a household-based, seroepidemiologic survey conducted in New York in 1999, using a cluster sample of 677 individuals, more than 2 hours spent outdoors after dusk or before dawn was associated with increased WNV seropositivity; DEET use was associated with decreased WNV seropositivity (4).
• DEET-based repellents provide longer protection against mosquitoes than other available products from a 2001 comparison of 16 available products (5).
• Effective prevention depends on integrated arboviral surveillance and control programs per expert recommendation (6).

Comments:

• Much of the research regarding the efficacy of decreasing mosquito bites as a primary prevention tool is derived from older studies of malaria, Japanese encephalitis, and St. Louis encephalitis and has not been specifically evaluated for WNV.
• No vaccine for WNV currently exists for humans.
• In addition to the preventive efforts of individuals, physicians, and patients, local jurisdictions implement vector control programs.