Delineating West Nile Virus Transmission Cycles at Various Scales: The Nearest Neighbor Distance–Time Model

Abstract

Various approaches are used to identify West Nile virus (WNV) exposure areas, including unusual sightings of infected dead birds, mosquito pools or human cases both prospectively and retrospectively. A significant and largely unmet need in WNV research is to incorporate the temporal characterization of virus spread and locational information of the three components of transmission cycle—i.e., birds (reservoir), mosquitoes (vector), and humans (host)—on a localized scale. Exposure areas containing all three components of the WNV cycle in close proximity have higher potential to amplify an outbreak as compared to exposure areas delineated by a single component. In this paper, we introduce a novel approach, termed ‘Nearest Neighbor Distance Time’ or NNDT, to identify and retrospectively monitor WNV transmission cycles on various scales in the Twin Cities Metropolitan area of Minnesota. The NNDT model was implemented in a geographic information system using data from the period 2002 to 2006. The results indicated that 2002 and 2003 had three such WNV cycles, followed by one, two, and four respectively in 2004, 2005, and 2006. The NNDT method can be useful in locating chronically exposed areas and generating hypotheses about the transmission of WNV.

Climate change impacts on West Nile virus transmission in a global context

“…This insight was evidenced recently in Europe and western Asia, when the outbreaks in the summers of 2011-2013 occurred in most of the same disease locations as in 2010, which was an extremely hot year [22,72]. Another example appeared in the northern USA when the increasing occurrences of warmer weather patterns lead to increased incidence of WNV infections [110].…”

Exploring the Spatio-Temporal Dynamics of Reservoir Hosts, Vectors, and Human Hosts of West Nile Virus: A Review of the Recent Literature

“…Using data from the Twin Cities Metropolitan Area of Minnesota (TCMA) for the years 2002 to 2006, Ghosh et al . [ 36 ] introduced the Nearest Neighbor Distance Time (NNDT) method for delineating WNV exposure areas and WNV transmission cycles. The NNDT method retrospectively identified WNV transmission cycles with an area ranging from 5 to 150 square miles.…”

“…After seeing the worst toll from West Nile, Texas declared a state of emergency, which has reached 270 cases and 11 deaths in Dallas County alone [ 35 ]. The increasing occurrences of warmer and wetter weather patterns in the northern United States have increased the mosquito life span leading to increased incidence of WNV infections [ 36 ].…”

A meta-analysis of the factors influencing development rate variation in Aedes aegypti (Diptera: Culicidae)

“…In particular, controlling the population of the mosquito vector Aedes aegypti (Linnaeus) is critical to preventing dengue infection [25], as there is no vaccine or chemotherapeutic treatment [26]. In Ae.…”

“…Particularly in insects of medical importance, such as mosquitoes that vector human pathogens, estimates of developmental characteristics and models of developmental timing are used to guide vector population control efforts [ 24 ]. In particular, controlling the population of the mosquito vector Aedes aegypti (Linnaeus) is critical to preventing dengue infection [ 25 ], as there is no vaccine or chemotherapeutic treatment [ 26 ]. In Ae.…”