Evaluating the use of house sparrow nestlings as sentinels for West Nile virus in Saskatchewan.
This study evaluated the use of house sparrow (Passer domesticus) nestlings as sentinels of West Nile virus (WNV) in the prairie grasslands of Saskatchewan. In the summer of 2006, 600 house sparrow nestlings were collected and pooled tissues tested by reverse transcriptase-polymerase chain reaction. All tested negative for WNV. During the same period, no WNV was detected by mosquito surveillance in the study area and 15 WNV-infected pools were collected from the nearby city of Estevan. Six percent of avian carcasses collected from Regina, a city 100 km from the study area in the same ecozone, were infected with WNV. In 2007, 200 house sparrow nestlings were collected and 4 tested positive for WNV, a prevalence of 2%. Ninety-seven house sparrow eggs were also collected and WNV antibodies were measured in the yolk. Seven eggs had measurable titers, a prevalence of 7.2%. Combined WNV surveillance showed high levels of WNV transmission in 2007; 112 WNV-infected mosquito pools were collected from nearby cities of Estevan and Weyburn, and the proportion of WNV infected avian carcasses from Regina was 78%. There were 1456 human cases of WNV in Saskatchewan in 2007, compared to 19 cases in 2006. The study concluded that house sparrow nestlings are not useful as an early warning of WNV circulation, or as a measure of the intensity of WNV activity in the prairie grasslands. Also, the study determined that maternally derived antibody did not have a significant limiting effect on WNV transmission to house sparrow nestlings in 2007, a year of epidemic WNV activity in the study area.
Millins
Caroline
C
Department of Veterinary Pathology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. caroline.millins@usask.ca
Reid
Alexandra
A
Curry
Phil
P
Drebot
Michael A
MA
Andonova
Maya
M
Buck
Peter
P
Leighton
Frederick A
FA
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D016133:Polymerase Chain Reaction; D012525:Saskatchewan / Q000453:epidemiology; D018571:Sentinel Surveillance; D046370:Sparrows / Q000097:blood / Q000821:virology*; D014901:West Nile Fever / Q000453:epidemiology / Q000662:veterinary*; D014902:West Nile virus / Q000276:immunology / Q000302:isolation & purification*
D000914:Antibodies, Viral