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ABSTRACT: SUMMARY Encephalitis is a clinical syndrome often associated with infectious agents. This study describes the epidemiology and disease burden associated with encephalitis in Canada and explores possible associations with arboviral causes. Encephalitis-associated hospitalizations, 1994-2008, were analysed according to aetiological category (based on ICD-9/ICD-10 codes) and other factors using multivariate logistic regression for grouped (blocked) data and negative binomial regression. A discrete Poisson model tested spatio-temporal clustering of hospitalizations associated with unclassified and arboviral encephalitis aetiologies. Encephalitis accounted for an estimated 24028 hospitalizations in Canada (5·2/100 000 population) and unknown aetiologies represented 50% of these hospitalizations. In 2003, clusters of unclassified encephalitis were identified in the summer and early autumn months signifying potential underlying arboviral aetiologies. Spatio-temporal patterns in encephalitis hospitalizations may help us to better understand the disease burden associated with arboviruses and other zoonotic pathogens in Canada and to develop appropriate surveillance systems.
Epidemiology and Infection 11/2012; · 2.84 Impact Factor
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Biodiversity. 01/2009; 10(2-3):83-91.
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Canadian family physician Medecin de famille canadien 11/2008; 54(10):1381-4. · 1.19 Impact Factor
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Canada communicable disease report = Relevé des maladies transmissibles au Canada 02/2008; 34(1):1-19.
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N H Ogden,
L Trudel, H Artsob,
I K Barker,
G Beauchamp,
D F Charron,
M A Drebot,
T D Galloway,
R O'Handley,
R A Thompson,
L R Lindsay
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ABSTRACT: Passive surveillance for the occurrence of the tick Ixodes scapularis Say (1821) and their infection with the Lyme borreliosis spirochaetes Borrelia burgdorferi s.l. has taken place in Canada since early 1990. Ticks have been submitted from members of the public, veterinarians, and medical practitioners to provincial, federal, and university laboratories for identification, and the data have been collated and B. burgdorferi detected at the National Microbiology Laboratory. The locations of collection of 2,319 submitted I. scapularis were mapped, and we investigated potential risk factors for I. scapularis occurrence (in Quebec as a case study) by using regression analysis and spatial statistics. Ticks were submitted from all provinces east of Alberta, most from areas where resident I. scapularis populations are unknown. Most were adult ticks and were collected in spring and autumn. In southern Québec, risk factors for tick occurrence were lower latitude and remote-sensed indices for land cover with woodland. B. burgdorferi infection, identified by conventional and molecular methods, was detected in 12.5% of 1,816 ticks, including 10.1% of the 256 ticks that were collected from humans and tested. Our study suggests that B. burgdorferi-infected I. scapularis can be found over a wide geographic range in Canada, although most may be adventitious ticks carried from endemic areas in the United States and Canada by migrating birds. The risk of Lyme borreliosis in Canada may therefore be mostly low but more geographically widespread than previously suspected.
Journal of Medical Entomology 06/2006; 43(3):600-9. · 1.76 Impact Factor
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ABSTRACT: The first confirmed case of hantavirus pulmonary syndrome in Manitoba was diagnosed in 1999. To define better the risk of exposure to hantaviruses in this area, the clinical features and epidemiological factors pertaining to this case were described, and a serological survey of rodents collected near the patient's residence was undertaken. Small mammals were collected using live traps, were anesthetized via inhalation of isoflurane and were bled. Human and mouse serologies were undertaken using an ELISA to detect hantavirus-specific immunoglobulin G and/or immunoglobulin M antibodies. In addition, a full medical and epidemiological assessment, as well as individual risk factor and exposure analysis, were conducted. A 27-year-old Manitoba woman presented with severe respiratory distress and diffuse bilateral air space disease radiologically. Despite extremely aggressive measures, including mechanical ventilation, antibiotics, fluid management and inotropic support, the patient's condition rapidly deteriorated, and she died 8 h after admission. Hantavirus pulmonary syndrome was confirmed by the detection of immunoglobulin M and immunoglobulin G antibodies to the Sin Nombre virus (SNV) in her sera and by the demonstration of SNV genomic sequences in her lung tissue. Exposure to hantavirus likely occurred in and around the home or in the rural area in which she resided. A total of 252 small mammals, primarily deer mice (Peromyscus maniculatus), were collected from 17 different sites at or near where the patient lived. Antibodies to SNV were detected in 28 of 244 (11.5%) deer mice, which were collected within 9 km of the residence of the fatal case, indicating that these rodents are a significant reservoir for SNV in this area.
The Canadian journal of infectious diseases = Journal canadien des maladies infectieuses 06/2001; 12(3):169-73. · 0.76 Impact Factor
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ABSTRACT: In Canada, hantavirus infected deer mice (Peromyscus maniculatus) have been collected from British Columbia to Newfoundland. Partial sequencing of G1 and N protein encoding regions from Canadian Peromyscus maniculatus-borne hantaviruses demonstrated the existence of significant genotypic divergence among strains. Phylogenetic analysis showed that Sin Nombre (SN)-like viruses from eastern and western Canadian deer mice can be divided into at least two broad-based genogroups. Sequencing of mitochondrial DNA from infected deer mice originating from various eastern and western provinces showed that SN-like virus genogroups appeared to be associated with distinct haplotypes of mice. Sera from deer mice infected with eastern and western viral genotypes neutralized the Sin Nombre virus strain, Convict Creek 107, but not the New York 1 hantavirus. Despite the genetic heterogeneity of Canadian SN-like strains these hantaviruses do not appear to define unique hantavirus serotypes.
Virus Research 06/2001; 75(1):75-86. · 2.94 Impact Factor
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Canada communicable disease report = Relevé des maladies transmissibles au Canada 09/2000; 26(16):133-4.
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Canada communicable disease report = Relevé des maladies transmissibles au Canada 05/2000; 26(8):65-9.
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ABSTRACT: Serum samples collected from 623 white-tailed deer (Odocoileus virginianus) in southern Ontario (Canada) from 1985 to 1989 were tested for antibodies to Borrelia burgdorferi using an indirect fluorescent antibody (IFA) staining method. Samples from 150 of the deer were also tested using an enzyme-linked immunosorbent assay (ELISA). At IFA titers of 1:64 and 1:128 deer with antibodies to B. burgdorferi appeared to be widespread throughout southern Ontario, with an apparent prevalence ranging from 3 to 47%. At IFA titres > or = 1:256 and ELISA titres > or = 1:160 deer with antibodies to B. burgdorferi were only present on Long Point which is the only known endemic focus of Ixodes scapularis, the primary vector for B. burgdorferi, in southern Ontario. At these titres the apparent prevalence of antibodies to B. burgdorferi on Long Point was only 5 to 7%, even though the mean intensity of infestation of adult I. scapularis on deer was > 180, and 60% of the adult ticks are infected with B. burgdorferi. Based on these results, white-tailed deer do not appear to be a good sentinel species for the distribution of B. burgdorferi.
Journal of wildlife diseases 04/1998; 34(2):411-4. · 1.08 Impact Factor
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ABSTRACT: This study applies and evaluates a variety of different measures of reproducibility. As an example, repeat enzyme-linked immunosorbent assays (ELISA) for antibodies to Borrelia burgdorferi, the etiologic agent of Lyme disease, are used. These repeat tests were part of the 1991 Quality Control Assessment of provincial laboratories that was carried out by the Laboratory Centre for Disease Control (Ottawa). Twenty-seven sera from cases and non-cases were tested by three laboratories, and two laboratories repeated the tests once. Methodological issues discussed include: different methods of assessing reproducibility in the continuous scale; whether reproducibility should be assessed with data in continuous or categorical form; problems assessing the reproducibility of data that has been standardized using a calibration-regression line; and problems with external generalizability of reproducibility studies of rare diseases. The authors conclude that the statistical method used to assess the reproducibility of a test must be adjusted to suit individual study designs and data, and the usage of the test.
Journal of Clinical Epidemiology 10/1995; 48(9):1123-32. · 4.27 Impact Factor
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The Canadian veterinary journal. La revue veterinaire canadienne 04/1995; 36(3):170-2. · 1.06 Impact Factor
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ABSTRACT: Lyme disease has been increasingly diagnosed throughout North America since the late 1970s. The clinical diagnosis and epidemiological monitoring of Lyme disease are aided by serological testing for the etiological agent, Borrelia burgdorferi. Numerous authorities have questioned the reproducibility of these serological tests. This study assessed the intra- and interlaboratory reproducibility of an elisa used to aid in the diagnosis of Lyme disease.
Twenty-seven sera from cases and noncases were tested by three laboratories. Two of the laboratories repeated the tests once. These testings were part of the 1991 quality control assessment of provincial laboratories carried out by the Laboratory Centre for Disease Control (lcdc), Ottawa.
The mean weighted kappa statistics were 0.87 for interlaboratory comparisons and 0.89 for intralaboratory comparisons.
Overall, the elisa assessed in this study demonstrated good to excellent intra- and interlaboratory reproducibility in the lcdc 1991 quality control assessment when the data were assessed in the categorical scale using the weighted kappa statistic. Generalization of these findings to clinical laboratory settings must be done with caution.
The Canadian journal of infectious diseases = Journal canadien des maladies infectieuses 03/1995; 6(2):90-5. · 0.76 Impact Factor
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ABSTRACT: A serological study was undertaken to determine whether dogs in Ontario are being exposed to Borrelia burgdorferi, the etiological agent of Lyme disease. This study consisted of a survey of randomly selected dogs and testing of diagnostic submissions from candidate Lyme disease cases. The survey of 1,095 dogs, bled between January 1988 and August 1989, revealed a total of 65 (5.9%) enzyme-linked immunosorbent assay (ELISA) reactors, of which 22 had immuno-fluorescent antibody assay (IFA) titers >/=1:32. All but one of the IFA-positive and 10 of the ELISA-positive, IFA-negative sera were further tested by western blot. Eight western blot positive and three equivocal reactors were obtained. Three of the eight confirmed reactors had visited areas known to be endemic for Lyme disease, leaving five reactors that might have been infected in previously undocumented areas for B. burgdorferi activity in Ontario. Diagnostic submissions of sera from 223 dogs were received between August 1987 and February 1992. Test results revealed 21 (9.4%) IFA reactors, of which only six had significant titers (>/=1:256) and were reactive by an immunodot Borrelia test. All six dogs had travelled to known Lyme endemic areas. Based on results obtained from this study, it seems likely that the agent of Lyme disease is not widespread in Ontario.
The Canadian veterinary journal. La revue veterinaire canadienne 09/1993; 34(9):543-8. · 1.06 Impact Factor
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ABSTRACT: Studies were undertaken to monitor for the presence of Borrelia burgdorferi, the etiologic agent of Lyme disease, on Prince Edward Island, Canada. Gut contents were removed for culturing from seven engorged ticks collected in 1991-1992 including five Ixodes dammini (Spielman, Clifford, Piesman & Corwin) and two I. scapularis (Say) removed from a dog that had recently traveled to the southern United States. B. burgdorferi was recovered from one I. dammini that had been removed from a cat in Charlottetown in October 1991. The cat had not traveled off the island. Immunofluorescent antibody (IFA) studies on sera from 75 dogs, 7 cats, and 8 white-tailed deer (Odocoileus virginianus) collected on Prince Edward Island between 1989 and 1992 revealed one reactor with an IFA titer > or = 1:256. The reactor was a dog with a history of travel to the United States. This report documents the first isolate of B. burgdorferi in Atlantic Canada, possibly because of the introduction of I. dammini on migratory birds. Serological studies do not indicate widespread occurrence of B. burgdorferi on Prince Edward Island.
Journal of Medical Entomology 12/1992; 29(6):1063-6. · 1.76 Impact Factor
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ABSTRACT: Ixodes dammini Spielman, Clifford, Piesman & Corwin was confirmed at Long Point, Lake Erie, Ontario, on small mammals and white-tailed deer and by dragging for ticks. Mean intensities of up to 16.2 larvae and 2.1 nymphs were found on Peromyscus leucopus (Rafinesque), with an overall prevalence of infestation up to 92%. Adult I. dammini (101.6 +/- 77.63) (mean +/- SD) were found on 8 white-tailed deer, Odocoileus virginianus (Zimmerman). The seasonal pattern of recovery of ticks from hosts and the environment resembled that described elsewhere. I. dammini was not found on 952 small mammals trapped at 25 other localities throughout Ontario, although other ticks (Derma-centor variabilis (Packard), Ixodes angustus Neumann, I. marxi Banks, I. muris Bishopp & Smith) were encountered sporadically. I. dammini is not widespread or common in Ontario other than at Long Point. Borrelia burgdorferi was isolated from 10 of 151 P. leucopus; from larval and nymphal I. dammini; and from nymphal and adult D. variabilis, all from Long Point. B. burgdorferi was not recovered from 116 small mammals from localities other than Long Point. Seropositive P. leucopus (indirect fluorescent antibody test titer > or = 1:20) were common (up to 30% prevalence in July 1988, n = 23) on Long Point. Where I. dammini was not found, the prevalence of seroreactors among Peromyscus was 0 (15 sites), < 12% (5 sites), and 29% (1 site); seroprevalence at 1:20 could not be calculated for a further 4 sites examined in 1987. Antibody to B. burgdorferi was also detected in other small mammals at some sites. Such antibody was interpreted as possibly cross-reacting or caused by direct transmission.
Journal of Medical Entomology 12/1992; 29(6):1011-22. · 1.76 Impact Factor
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ABSTRACT: Jamestown Canyon (JC) virus of the California (CAL) serogroup has been isolated in 12 American states and 6 Canadian provinces. A study was undertaken to produce monoclonal antibodies (MAbs) to JC virus and to use these MAbs to assay for possible heterogeneity among naturally occurring JC topotypes in Canada. MAbs were produced to the prototype strain of JC virus using BALB/c mice. Twenty-seven secreting MAbs were obtained and three of these MAbs were propagated and studied. All three MAbs, M1 (IgG1), M2 (IgG2b), and M3 (IgG2a), were reactive by immunofluorescent antibody assay against JC-infected vero cells and by ELISA against JC antigen. MAb M2 reacted with all members of the Melao complex, MAb M1 reacted only with Keystone virus, while MAb M3 exhibited no reactivity with other CAL serogroup viruses. Only MAb M3 possessed neutralization and hemagglutination inhibition activities against JC virus. The MAbs were also tested by ELISA and for neutralizing activity against 13 JC topotypes isolated in 5 provinces from Newfoundland to Saskatchewan. ELISA confirmed closer identity of the Canadian topotypes to JC as opposed to the closely related South River virus. The MAbs verified all Canadian topotypes to be JC virus but revealed different patterns of reactivity between these topotypes and prototype JC virus.
Viral Immunology 02/1992; 5(3):233-42. · 1.97 Impact Factor
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ABSTRACT: A rhabdovirus, Mn 936-77, was isolated from a pool of two Culex tarsalis collected on August 16, 1977, from Morris, Manitoba. Isolate Mn 936-77 was not pathogenic for suckling Swiss white mice inoculated by the intracerebral route. The virus propagated in three vertebrate cell lines (Vero, primary chick embryo, mouse neuroblastoma), but apparently not in Aedes albopictus C6/36 cells. Isolate Mn 936-77 did not react by amplified enzyme-linked immunosorbant assay with 230 viruses of proven or possible arbovirus etiology or by immunofluorescence with 88 members of the family Rhabdoviridae. Isolate Mn 936-77 appears to be a newly discovered virus for which the name Manitoba virus is proposed.
Canadian Journal of Microbiology 06/1991; 37(5):329-32. · 1.36 Impact Factor
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ABSTRACT: Swelling and erythema of the right pinna developed in a 7-year-old girl. Six months later a biopsy specimen showed a dense, diffuse lymphoplasmacytic infiltrate involving most of the dermis except for a thin Grenz zone. The appearance was consistent with lymphocytoma cutis. She had been bitten by a tick on the right ear in Switzerland 6 weeks before the onset of the lesion. Serologic tests by enzyme-linked immunosorbent assay for Borrelia burgdorferi, done 6 and 11 months after the bite, yielded optical density readings of 1.04 and 0.65, respectively; indirect immunofluorescence yielded titers of 1:256 and 1:128. A Borrelia-like organism was identified by a modified Steiner stain; immunohistochemistry was noncontributory. The spirochetal origin of lymphadenosis benigna cutis is briefly reviewed.
Journal of the American Academy of Dermatology 05/1991; 24(4):621-5. · 3.99 Impact Factor
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ABSTRACT: In June 1990 a quality control assessment was undertaken of Canadian public health laboratories testing for antibodies to Borrelia burgdorferi, the etiological agent of Lyme disease. Twenty sera were distributed to nine laboratories, including 12 obtained from patients in Lyme endemic areas and presumed to be serological positives, and eight prescreened negative controls. Seventeen serological reports were submitted, comprising nine enzyme-linked immunosorbent assays (elisa), six immunofluorescent assays and two Western blot assessments. Antibodies were detected in 11 of the 12 sera which had been presumed to be positive. Assuming 11 positive sera had been submitted, the test sensitivities varied from 88.9 to 100% by elisa, and 54.5 to 90.1% by immunofluorescent assay. Specificities were 100% for all but one elisa and one immunofluorescent assay assessment. The results indicate a satisfactory performance by elisa but a need for upgrading or replacement of some immunofluorescent assay tests.
The Canadian journal of infectious diseases = Journal canadien des maladies infectieuses 01/1991; 2(1):41-5. · 0.76 Impact Factor
