Characterizing environmental risk factors for West Nile virus in Quebec, Canada, using clinical data in humans and serology in pet dogs

Abstract

The identification of specific environments sustaining emerging arbovirus amplification and transmission to humans is a key component of public health intervention planning. This study aimed at identifying environmental factors associated with West Nile virus (WNV) infections in southern Quebec, Canada, by modelling and jointly interpreting aggregated clinical data in humans and serological data in pet dogs. Environmental risk factors were estimated in humans by negative binomial regression based on a dataset of 191 human WNV clinical cases reported in the study area between 2011 and 2014. Risk factors for infection in dogs were evaluated by logistic and negative binomial models based on a dataset including WNV serological results from 1442 dogs sampled from the same geographical area in 2013. Forested lands were identified as low-risk environments in humans. Agricultural lands represented higher risk environments for dogs. Environments identified as impacting risk in the current study were somewhat different from those identified in other studies conducted in north-eastern USA, which reported higher risk in suburban environments. In the context of the current study, combining human and animal data allowed a more comprehensive and possibly a more accurate view of environmental WNV risk factors to be obtained than by studying aggregated human data alone.

Risk factors associated with seropositivity to California serogroup viruses in humans and pet dogs, Quebec, Canada

“…and agricultural lands, and Cx. pipiens, which is abundant in agricultural, urban and suburban areas), seems consistent with the areas of lower risk identified in the current study [34,35]. Grimstad et al previously reported a correlation between white-tailed deer densities and seroprevalence for JCV in humans [36].…”

“…vexans , which is found in abundance in alluvial plains and agricultural lands, and Cx. pipiens , which is abundant in agricultural, urban and suburban areas), seems consistent with the areas of lower risk identified in the current study [34, 35].…”

“…Moreover, given that CSGV has been active for decades in the study area [34], seroconversion may have occurred at any time in the past, in areas distant from the house location of participants, at time of the study. However, based on our previously published data on the cohort of dogs included in this study [35], 61% of the sampled dogs had never left their municipality of residence, suggesting that exposure misclassification may be relatively limited in dogs [35].…”

“…An increased awareness of the potential infection with CSGV viruses in patients presenting with symptoms of encephalitis and a history of frequent exposure to mosquito bites in forested areas of Québec would be warranted. Of importance is the identification of woodland habitats ( vs. agricultural land and suburban environments) as risk environments for exposure to CSGV, which is the opposite to what has been found in Quebec and/or other parts of North America for WNV [27, 28, 35]. Therefore, the risk from mosquito-borne arboviruses is present in many different habitats, but the precise type of risk varies with habitat.…”

Comparison of Japanese Encephalitis Force of Infection in Pigs, Poultry and Dogs in Cambodian Villages

“…Therefore, other domestic animals that are housed in close proximity to humans should be investigated as a suitable sentinel. Previous studies showed that dogs could be good sentinels for West Nile virus [ 33 , 34 ], Lyme disease [ 35 ] and other arthropod-borne diseases [ 36 ]. In addition, exposure of dogs to JEV has already been observed in Singapore and Japan [ 8 , 24 ].…”