1. Lyme Ontario, Research Division, 365 St. David St. South, Fergus, Ontario, Canada N1M 2L7;
2. Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California 95616, United States of America;
3. Epidemiology & Environmental Health, Department of Public Health, University of North Florida, 1 UNF Drive, Jacksonville, Florida 32224, United States of America;
4. Department of Entomology and Center for Vector Ecology and Zoonotic Diseases. The Connecticut Agricultural Experiment Station, P.O. Box 1106, New Haven, Connecticut 06504-1106, United States of America;
5. Department of Biology, Georgia Southern University, 4324 Old Register Road, Statesboro, Georgia 30458, United States of America.
We document an established population of blacklegged ticks, Ixodes scapularis, on Corkscrew Island, Kenora District, Ontario, Canada. Primers of the outer surface protein A (OspA) gene, the flagellin (fla) gene, and the flagellin B (flaB) gene were used in the PCR assays to detect Borrelia burgdorferi sensu lato (s.l.), the Lyme disease bacterium. In all, 60 (73%) of 82 adult I. scapularis, were infected with B. burgdorferi s.l. As well, 6 (43%) of 14 unfed I. scapularis nymphs were positive for B. burgdorferi s.l. An I. scapularis larva was also collected from a deer mouse, and several unfed larvae were gathered by flagging leaf litter. Based on DNA sequencing of randomly selected Borrelia amplicons from six nymphal and adult I. scapularis ticks, primers for the flagellin (fla) and flagellin B (flaB) genes reveal the presence of B. burgdorferi sensu stricto (s.s.), a genospecies pathogenic to humans and certain domestic animals. We collected all 3 host-feeding life stages of I. scapularis in a single year, and report the northernmost established population of I. scapularis in Ontario. Corkscrew Island is hyperendemic for Lyme disease and has the highest prevalence of B. burgdorferi s.l. for any established population in Canada. Because of this very high infection prevalence, this population of I. scapularis has likely been established for decades. Of epidemiological significance, cottage owners, island visitors, outdoors enthusiasts, and medical professionals must be vigilant that B. burgdorferi s.l.-infected I. scapularis on Corkscrew Island pose a serious public health risk.
Keywords: blacklegged tick, Ixodes scapularis, Lyme disease, Borrelia burgdorferi, infection prevalence, Kenora District, Ontario