Article

Epidemiology and Transmission Dynamics of West Nile Virus Disease

Centers for Disease Control and Prevention, Fort Collins, Colorado 80526, USA.
Emerging infectious diseases (Impact Factor: 7.33). 08/2005; 11(8):1167-73. DOI: 10.3201/eid1108.050289a
Source: PubMed

ABSTRACT From 1937 until 1999, West Nile virus (WNV) garnered scant medical attention as the cause of febrile illness and sporadic encephalitis in parts of Africa, Asia, and Europe. After the surprising detection of WNV in New York City in 1999, the virus has spread dramatically westward across the United States, southward into Central America and the Caribbean, and northward into Canada, resulting in the largest epidemics of neuroinvasive WNV disease ever reported. From 1999 to 2004, >7,000 neuroinvasive WNV disease cases were reported in the United States. In 2002, WNV transmission through blood transfusion and organ transplantation was described for the first time, intrauterine transmission was first documented, and possible transmission through breastfeeding was reported. This review highlights new information regarding the epidemiology and dynamics of WNV transmission, providing a new platform for further research into preventing and controlling WNV disease.

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    • "The passive system of reporting of equine cases by sentinel veterinarians in France was found to be a cost-effective and efficient method of early detection of virus activity when compared to sentinel horses, sentinel chickens, and mosquito testing by using mathematical modeling to simulate data for low activity and endemic and epidemic situations (Chevalier et al. 2011). Although equines frequently are vaccinated in California (American Association of Equine Practitioners 2012) and, therefore, our horse population has not experienced the recent epizootics seen in France (Hayes et al. 2005), our results for areas with a susceptible bird population agree that passive surveillance is the most cost-effective system for WNV surveillance. Higher densities of mosquito traps resulted in more precise estimates of infection prevalence in both trap types. "
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    ABSTRACT: Surveillance systems for West Nile virus (WNV) combine several methods to determine the location and timing of viral amplification. The value of each surveillance method must be measured against its efficiency and costs to optimize integrated vector management and suppress WNV transmission to the human population. Here we extend previous comparisons of WNV surveillance methods by equitably comparing the most common methods after standardization on the basis of spatial sampling density and costs, and by estimating optimal levels of sampling effort for mosquito traps and sentinel chicken flocks. In general, testing for evidence of viral RNA in mosquitoes and public-reported dead birds resulted in detection of WNV approximately 2-5 weeks earlier than serological monitoring of sentinel chickens at equal spatial sampling density. For a fixed cost, testing of dead birds reported by the public was found to be the most cost effective of the methods, yielding the highest number of positive results per $1000. Increased spatial density of mosquito trapping was associated with more precise estimates of WNV infection prevalence in mosquitoes. Our findings also suggested that the most common chicken flock size of 10 birds could be reduced to six to seven without substantial reductions in timeliness or sensitivity. We conclude that a surveillance system that uses the testing of dead birds reported by the public complemented by strategically timed mosquito and chicken sampling as agency resources allow would detect viral activity efficiently in terms of effort and costs, so long as susceptible bird species that experience a high mortality rate from infection with WNV, such as corvids, are present in the area.
    Vector borne and zoonotic diseases (Larchmont, N.Y.) 02/2015; 15(2):147-155. DOI:10.1089/vbz.2014.1689 · 2.53 Impact Factor
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    • "However, its importance is likely to be higher outside urban areas where their preferred breeding sites are more common and the abundance of wild animals is higher. Outside of Austria, Ae. vexans has been shown to serve as a vector for WNV (USA; Hayes et al. 2005) and for dirofilariasis (Slovakia; Bocková et al. 2013). Similar to Ae. vexans, the preferred breeding sites of Oc. sticticus are temporary water bodies after floodings (Becker et al. 2010). "
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    Parasitology Research 12/2014; 114:707-713. DOI:10.1007/s00436-014-4237-6 · 2.33 Impact Factor
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    • "the WNV was introduced to North America (Hayes et al. 2005; Reimann et al. 2008; Syed and Leal 2009), which resulted in a rapid dissemination across the continent, where the virus now is endemic. Throughout the period 2010–2013, several human cases of WNV infections were also reported in Greece, mainly in the northern parts of the country, with a countrywide total of 610 diagnosed cases and 71 fatalities (HCDCP 2013). "
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    Parasitology Research 09/2014; 113(11). DOI:10.1007/s00436-014-4152-x · 2.33 Impact Factor
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