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Volume 25-09 |
VECTOR OF LYME BORRELIOSIS, IXODES SCAPULARIS, IDENTIFIED IN SASKATCHEWANA passive surveillance program was initiated in Saskatchewan in 1998 to determine whether the blacklegged tick, Ixodes scapularis (formerly Ixodes dammini), was present in this province. Seven tick species were present in the 195 collections submitted in 1998 (Table 1). Although the American dog tick, Dermacentor variabilis, comprised the majority of the specimens submitted from Saskatchewan in 1998, four adults of I. scapularis were also collected. The first blacklegged tick specimen, a partially fed female, was removed from a cat after a weekend trip to Christopher Lake, Saskatchewan, on 16 May 1998. The second specimen, a male, was submitted on 22 May 1998 by a resident of Langenburg, Saskatchewan. Unfortunately, the owner had been collecting and communally storing specimens removed from his cat and other domestic animals since 1996 and thus it was not possible to determine the host or the date that the specimen was collected. The third specimen, an engorged female, was removed from a dog on 15 October 1998. Although the animal resided in Regina, Saskatchewan, it had traveled with its owner to Brandon, Manitoba, from 9 to 12 October 1998 and thus this specimen was acquired either on route between Regina and Brandon, in the Brandon area or in Regina. The last specimen, a partially fed female, was removed from a dog on 10 November 1998. The dog resided in Saskatoon, Saskatchewan, and except for daily walks in the adjacent countryside had not left Saskatchewan since mid-August. Table 1 Ticks collected in Saskatchewan during a passive surveillance program conducted in 1998
These are the first published records in Saskatchewan of this important vector of Borrelia burgdorferi, the causative agent of Lyme borreliosis. Other agents associated with I. scapularis in the United States include the rickettsia, Ehrlichia phagocytophila/equi (responsible for human granulocytic ehrlichiosis), the protozoon, Babesia microti (responsible for human babesiosis) and a newly discovered flavivirus tentatively named deer tick virus(1). In Canada, the distribution of I. scapularis is uneven and focal. Although adult I. scapularis have been detected, in low numbers, in southern Manitoba(2,3), Ontario(4-7), the eastern townships of Quebec(8), Nova Scotia(9,10), New Brunswick (unpublished data: Zoonotic Diseases, Bureau of Microbiology, Laboratory Centre for Disease Control, Winnipeg), Prince Edward Island(11-13) and Newfoundland(14), at the present time, reproducing populations of I. scapularis are only known to be established on the Long Point peninsula(15) and Point Pelee National Park (unpublished data: Zoonotic Diseases, Bureau of Microbiology, Laboratory Centre for Disease Control, Winnipeg), both of which are located on Lake Erie, Ontario. The adult blacklegged ticks collected in non-endemic areas of Canada, including Saskatchewan, likely were transported to these localities, as larvae or nymphs, on birds migrating from endemic areas to the south(16), and were fortuitously found by passive surveillance. Although specimens of I. scapularis have been collected from widely separated localities in Canada, this does not mean that reproducing tick populations are established in these areas. Though testing to determine whether the blacklegged ticks collected in Saskatchewan were infected with B. burgdorferi has not been completed to date, the discovery of these ticks is evidence that people (or their pets) living in Saskatchewan are at risk of contacting potentially infected blacklegged ticks within the province. Small numbers of I. scapularis infected with B. burgdorferi have been detected in provinces where blacklegged ticks are not considered endemic including Manitoba, mainland Ontario (i.e. areas outside of Long Point and Point Pelee), Quebec, New Brunswick, and Prince Edward Island(6,7,11) , (unpublished data: Zoonotic Diseases, Bureau of Microbiology, Laboratory Centre for Disease Control, Winnipeg). Only two people have been identified with antibodies to B. burgdorferi in Saskatchewan to date; however, both had travelled to Lyme-endemic areas and presumably were not infected in Saskatchewan (unpublished data: Saskachewan Health, Provincial Laboratory, Regina). Despite the apparent lack of locally acquired cases of Lyme borreliosis, physicians, and veterinarians should be aware of the discovery of I. scapularis in Saskatchewan and Lyme borreliosis should be considered in their diagnoses when patients present with consistent symptoms (or clinical signs). References
Source: R Lindsay, PhD, H Artsob, PhD, Zoonotic Diseases Section, Bureau of Microbiology, Laboratory Centre for Disease Control, T Galloway PhD, Department of Entomology, University of Manitoba, Winnipeg MB; G Horsman, MD, Medical Director, Provincial Laboratories, Saskatchewan Health, Regina SK.
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Last Updated: 2002-11-08 |  |
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