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Applied and Environmental Microbiology, March 2008, p. 1780-1790, Vol. 74, No. 6
0099-2240/08/$08.00+0 doi:10.1128/AEM.01982-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Foodborne, Waterborne and Zoonotic Infections Division, Public Health Agency of Canada, Ottawa, Ontario, Canada,1 Groupe de Recherché en Épidémiologie des Zoonoses et Santé Publique, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Quebec, Canada,2 Special Pathogens Division, Public Health Agency of Canada, National Microbiology Laboratory, Winnipeg, Manitoba, Canada,3 Department of Microbiology and Immunology, New York Medical College, Valhalla, New York,4 Canadian Cooperative Wildlife Health Centre, Department of Pathobiology, University of Guelph, Guelph, Ontario, Canada,5 International Development Research Centre, Ottawa, Ontario, Canada,6 Bird Studies Canada, Port Rowan, Ontario, Canada,7 Migratory Bird Populations Division, Canadian Wildlife Service, Environment Canada, Ottawa, Ontario, Canada,8 Department of Community Health and Epidemiology, Queen's University, Kingston, Ontario, Canada9
Received 29 August 2007/ Accepted 20 January 2008
During the spring in 2005 and 2006, 39,095 northward-migrating land birds were captured at 12 bird observatories in eastern Canada to investigate the role of migratory birds in northward range expansion of Lyme borreliosis, human granulocytic anaplasmosis, and their tick vector, Ixodes scapularis. The prevalence of birds carrying I. scapularis ticks (mostly nymphs) was 0.35% (95% confidence interval [CI] = 0.30 to 0.42), but a nested study by experienced observers suggested a more realistic infestation prevalence of 2.2% (95% CI = 1.18 to 3.73). The mean infestation intensity was 1.66 per bird. Overall, 15.4% of I. scapularis nymphs (95% CI = 10.7 to 20.9) were PCR positive for Borrelia burgdorferi, but only 8% (95% CI = 3.8 to 15.1) were positive when excluding nymphs collected at Long Point, Ontario, where B. burgdorferi is endemic. A wide range of ospC and rrs-rrl intergenic spacer alleles of B. burgdorferi were identified in infected ticks, including those associated with disseminated Lyme disease and alleles that are rare in the northeastern United States. Overall, 0.4% (95% CI = 0.03 to 0.41) of I. scapularis nymphs were PCR positive for Anaplasma phagocytophilum. We estimate that migratory birds disperse 50 million to 175 million I. scapularis ticks across Canada each spring, implicating migratory birds as possibly significant in I. scapularis range expansion in Canada. However, infrequent larvae and the low infection prevalence in ticks carried by the birds raise questions as to how B. burgdorferi and A. phagocytophilum become endemic in any tick populations established by bird-transported ticks.
Published ahead of print on 1 February 2008.
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