A critical area of interest in climate change studies is human health. In particular, certain diseases of tropical origin are potentially very sensitive to climate change (i.e., malaria, dengue fever, and West Nile Virus) and likely to change their distributions in the coming decades. The circumpolar region may be at greatest risk as it is experiencing some of the most rapid climate change and shifts in seasonality (IPCC, 2007). The potential impact of invasive diseases on immunologically naïve populations is unknown: understanding geographic variation in genes associated with disease resistance and susceptibility are, therefore, important avenues of research for circumpolar epidemiological modeling and triage. The particular focus of this pilot project is to examine genetic variation associated with increased susceptibility to West Nile Virus (WNV).
Why WNV? While malaria and dengue are considered lethal potential expansion diseases (Patz et al., 1996), recent studies indicate malaria may actually decrease in prevalence relative current climate change predictions (Paaijmans et al., 2009; Paaijmans et al., 2010). And dengue, despite much research, is poorly understood in terms of variation in host responses to infection (Coffey et al., 2009). WNV is an arbovirus most commonly transmitted via mosquito bites. WNV has expanded the northern boundaries of its distribution in recent decades and is commonly listed as a potential human health impact to the circumpolar region—areas that not only include Alaska and Canada but Iceland, Greenland and parts of Asia and Europe (Evengard and Sauerborn, 2009; Parkinson and Butler, 2005). Increased susceptibility to WNV is associated with a 32bp deletion in the CCR5 gene (Glass et al. 2006).
Risk factors associated with circumpolar populations (particularly indigenous or those in remote areas) include the presence of common disease vectors and nutritional changes that increase susceptibility to disease. Both WNV and filariasis rely on various species of mosquitos as vectors, some of which are present in the circumpolar region. Shifts in climate may increase breeding seasons and the number of generations per season, creating an overall higher likelihood that enough vectors will be available for transmission to human hosts. Remote villages where infection can spread rapidly are at greater risk. In addition, arctic populations have increased vitamin D deficiency (due to low UVB exposure during much of the year) which has been associated with increased disease vulnerability (Sharma et al., 2011). In addition, consumption of traditional foods (which supplied adequate vitamin D) has decreased due to climate change related reduced resource availability: this dietary shift toward western foods has decreased availability of adequate nutrition. These have a total effect of chronic immune system impairment.
2011 PI: NIH Alaska INBRE. $5000
2016 PI: NIH Alaska INBRE. $2000
Hoover KC. Paleogenomic epidemiology and CCR5. In second review with PLOS ONE (resubmitted 25 January 2018). Preprint: https://www.biorxiv.org/content/early/2017/09/27/195081
2016. Hoover KC and Barker C. West Nile Virus, Climate Change, and Circumpolar Vulnerability. Wiley Interdisciplinary Reviews: Climate Change 7(2):283-300. (Invited review) DOI: 10.1002/wcc.382 (5 Year Impact Factor: 5.185). Role: intellectual lead on overall paper, genetic epidemiology, and high latitude/circumpolar vulnerability; production of original manuscript; collaborative work on WNV background and final manuscript.