Genetic Susceptibility to West Nile Virus and Dengue

Loeb M.
Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ont., Canada
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Corresponding Author

Outline

Key Words 

Epidemiology
Genetic
Genomic analysis of complex diseases

Abstract
This article focuses on the host genetic predisposition to 2 viruses, West Nile virus and dengue virus, which belong to the genus Flavivirus. Although by definition these viruses have shared characteristics (e.g. similar size, single stranded, RNA viruses, both transmitted by the bite from an infected mosquito), they differ greatly in epidemiology and clinical manifestations. The text below not only summarizes the genetic factors that predispose to complications of these 2 important flaviviruses, but also illustrates the challenges in determining the genomic basis for complications to these viruses.
Copyright © 2013 S. Karger AG, Basel

West Nile Virus
Serious clinical illness due to West Nile virus (WNV) emerged rather dramatically in North America, beginning with a large outbreak in New York City in 1999. Since that time, WNV emerged as an important human pathogen in North America, where it eventually became reported in a majority of states and provinces in the US and Canada [1]. Although the incidence of reported cases has changed from year to year, the severe complications that can occur in infected cases remain a concern. It is notable that of those infected with this virus, approximately 20% develop mild symptoms, so-called ‘West Nile Fever' which is characterized by manifestations such as fever, malaise, headache, myalgia, and rash. Only 1 in ∼150 individuals who are infected develops meningitis or encephalitis [2]. This is suggestive for a genetic susceptibility in humans. The incidence of severe neurological syndromes increases with age (this includes encephalitis, meningitis, acute flaccid paralysis, peripheral neuropathy, polyradiculopathy, optic neuritis, and acute demyelinating encephalitis) and with immunosuppression. The absence of other well-defined risk factors again suggest that there is an underlying genetic predisposition to complications of disease.