Bird species involved in West Nile virus epidemiological cycle in
southern Quebec
Abstract
There have been many studies of the ecology of West Nile Virus (WNV) in
the US, including the role of different bird species as reservoirs and
mid-late summer shifts of feeding of Culex pipiens-restuans (CPR)
mosquitoes from birds to mammals. It is often assumed that these
findings are generalizable to neighbouring regions of Canada where WNV
is endemic; however there have been little equivalent studies in Canada
to confirm that this is reasonable. Here we construct a priority list of
bird species likely involved in the transmission of WNV in the greater
Montreal area by combining three sources of data i) results of WNV
surveillance in wild (dead) birds in the province (2002-2015); ii)
evidence from molecular blood meal analysis that bird species are fed
upon by CPR, the primary enzootic vectors of WNV in the region,
collected in mosquito surveillance in the study area in 2008 and 2014;
and iii) a literature review on evidence of sero-prevalence and host
competence of resident bird species. Three lists of 18, 23 and 53 bird
species, respectively, from the three data sources, and totalizing 67
bird species were identified as potential WNV reservoirs/amplifiers. Of
the 23 species identified from CPR blood meals, Common starlings,
American robins, Song and House sparrows ranked the highest as possible
WNV reservoirs/amplifiers. In addition, we found using logistic
regression that the proportion of blood meals taken from birds compared
to mammals by CPR declined significantly with surveillance week. These
findings indicate broad similarity in the ecology of WNV between the
study region and northeastern US although the relative importance of
some bird species as hosts of CPR and WNV in this area may be somewhat
different, and field studies are needed to confirm this, and explore the
consequences for the risk of WNV to the human population.