Thomas A. Sharon, R.N., M.P.H.

West Nile Virus is an infectious communicable disease contracted from Mosquito bites (Tabachnick, W.J. 2012). The mosquitoes act as vectors transmitting the virus from dead birds to indigenous animals and humans. Tabachnick conducted a survey and found that 20% of infected persons develops clinical West Nile Virus syndrome with a risk of encephalitis. Petersen, L.R. et al reported that there were over 3 million infections in the United States between 1999 and 2010 with approximately 780,000 cases of clinical disease. Therefore when there is an outbreak and suspected mosquito infestation 18-20 percent of the local population is at risk.

West Nile virus causes severe neurological disease. One study showed that there is increased risk of death with age over 54 and with underlying diabetes and Cardiovascular disease as an additional risk factor (Sejvar, J.J. et al 2011). These authors suggested that the neuroinvasive nature of this disease requires primary prevention actions among person over 50 years of age with close monitoring for pulmonary and cardiac complications in those who are positive for symptomatic infection.

Vaccines for West Nile Virus have been available since 2009 but safety and efficacy required further study. Recent double-blind, placebo-controlled study results have demonstrated that chimeric West Nile virus (WNV) vaccines are both relatively safe and effective in establishing immunity prior to infection (Biedenbender, R., et al 2011). The extent of side effects if any is unknown as of this writing. However, in view of the foregoing information, the particular activities required to reduce the risk of clinical infection in the target population are to reduce exposure to mosquito bites and encourage members of the target community to obtain WNV vaccines at the public health clinic.

West Nile virus causes severe neurological disease often resulting in chronic fatigue and paralysis. One study showed that there is increased risk of death with age over 54 and with underlying diabetes and Cardiovascular disease as an additional risk factor (Sejvar, J.J. et al 2011). These authors suggested that the neuroinvasive nature of this disease requires primary prevention actions among person over 50 years of age with close monitoring for pulmonary and cardiac complications in those who are positive for symptomatic infection.

Vaccines for West Nile Virus have been available since 2009 but safety and efficacy required further study. Recent double-blind, placebo-controlled study results have demonstrated that chimeric West Nile virus (WNV) vaccines are both relatively safe and effective in establishing immunity prior to infection (Biedenbender, R., et al 2011). The extent of side effects if any is unknown as of this writing. However, in view of the foregoing information, the particular activities required to reduce the risk of clinical infection in the target population are to reduce exposure to mosquito bites and encourage members of the target community to obtain WNV vaccines at the public health clinic.

Prevention

There are two ways to prevent WNV: 1) Take the vaccine; 2) Prevent mosquito bites.

The vaccine is especially important to people over 50 years of age and to anyone with diabetes and heart disease.

Prevention of mosquito bites requires the following actions:

1. Cleaning up mosquito breeding areas;
2. Wearing long sleeves and using insect repellents appropriately;
3. Checking window and door screens for holes and repairing or replacing them;
4. Providing mosquito netting for toddlers and infants.

References:

Biedenbender, R., Bevilacqua, J., Gregg, A.M., Watson, M., Dayan, G. (2011). Phase II, randomized, double-blind, placebo-controlled, multicenter study to investigate the immunogenicity and safety of a West Nile virus vaccine in healthy adults.  Journal of Infectious  Disease. 203(1), Pp. 75–84.

L. R. Petersen, P. J. Carson, B. J. Biggerstaff, B. Custer, S. M. Borchardt and M. P. Busch (2012). Estimated cumulative incidence of West Nile virus infection in US adults, 1999–2010. Epidemiology and Infection. Available on CJO2012 doi:10.1017/S0950268812001070

Sejvar, J.J., Lindsey, N.P., Campbell, G.L. (2011). Primary Causes of Death in Reported Cases of Fatal West Nile Fever, United States, 2002–2006 . Vector-Borne and Zoonotic Diseases. 11(2): 161-164. doi:10.1089/vbz.2009.0086.

United States Department of Health and Human Services (2009) Community Health Status Indicators Obtained on 10/16/12 from the internet at http://www.communityhealth.hhs.gov/Demographics.aspx?GeogCD=12086&PeerStrat=1&state=Florida&county=Miami-Dade

Walter, W.J. (2012). Sentinel Surveillance and Human Risk for West Nile Virus. Florida Medical Entomology Laboratory, Obtained from the University of Florida Website. http://fmel.ifas.ufl.edu/buzz/wtsentinel.shtml on 10/16/12.

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