BackgroundNorthward expansion of the tick Ixodes scapularis is driving Lyme disease (LD) emergence in Canada. Information on mechanisms involved is needed to enhance surveillance and identify where LD risk is emerging.ObjectivesWe used passive and active surveillance and phylogeographic analysis of Borrelia burgdorferi to investigate LD risk emergence in Quebec.MethodsIn active surveillance, we collected ticks from the environment and from captured rodents. B. burgdorferi transmission was detected by serological analysis of rodents and by polymerase chain reaction assays of ticks. Spatiotemporal trends in passive surveillance data assisted interpretation of active surveillance. Multilocus sequence typing (MLST) of B. burgdorferi in ticks identified likely source locations of B. burgdorferi.ResultsIn active surveillance, we found I. scapularis at 55% of sites, and we were more likely to find them at sites with a warmer climate. B. burgdorferi was identified at 13 I. scapularis–positive sites, but infection prevalence in ticks and animal hosts was low. Low infection prevalence in ticks submitted in passive surveillance after 2004—from the tick-positive regions identified in active surveillance—coincided with an exponential increase in tick submissions during this time. MLST analysis suggested recent introduction of B. burgdorferi from the northeastern United States.ConclusionsThese data are consistent with I. scapularis ticks dispersed from the United States by migratory birds, founding populations where the climate is warmest, and then establishment of B. burgdorferi from the United States several years after I. scapularis have established. These observations provide vital information for public health to minimize the impact of LD in Canada.

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Due to recent establishment of the blacklegged tick, Ixodes scapularis Say, in southeastern Canada, tick-borne zoonoses (Lyme disease, human granulocytotropic anaplasmosis, and babesiosis) are of growing concern for public health. Using white-tailed deer (Odocoileus virginianus) culled in southwestern Quebec during 2007-2008, we investigated whether hunter-killed deer could act as sentinels for early establishing tick populations and for tick-borne pathogens. Accounting for environmental characteristics of culling sites, and age and sex of deer, we investigated whether their tick infestation levels could identify locations of known tick populations detected in active surveillance, presumed tick populations detected by passive surveillance, or both. We also used spatial cluster analyses to identify spatial patterns of tick infestation and occurrence of tick-borne zoonoses infection in ticks collected from the deer. Adult ticks were found on 15% of the 583 deer examined. Adult male deer had the greatest number (approximately 90%) of adult ticks. Overall, 3, 15, and 0% of the ticks collected were polymerase chain reaction (PCR)-positive for Borrelia burgdorferi, Anaplasma phagocytophilum, and Babesia microti, respectively. Our statistical analyses suggest that sex and age of deer, temperature, precipitation, and an index of tick dispersion by migratory birds were significantly associated with tick infestation levels. Cluster analysis identified significant clusters of deer carrying ticks PCR-positive for A. phagocytophilum, and for deer carrying two or more I. scapularis. Our study suggests that hunter-killed deer may be effective as sentinels for emerging areas of tick-borne anaplasmosis. They may have limited use as sentinels for early emerging I. scapularis tick populations and emerging Lyme disease risk.

In January 2011, multiple acute gastroenteritis outbreaks that spanned many days and were related to attendance at funerals were reported to public health units in Quebec. An epidemiological investigation was initiated to identify the source of the contamination and to explain the extent of the contamination over time. Thirty-one cohorts of individuals attended different funerals held between 14 and 19 January. All attendees were served a cold buffet made by the same caterer. Of these 31 cohorts, 16 (with a total of about 800 people) contained individuals who reported being ill after the funeral. Symptoms were mainly diarrhea (89 to 94% of individuals), vomiting (63 to 90%,) and fever (26 to 39%), with a median incubation period of 29 to 33 h and a median duration of symptoms of 24 to 33 h, suggesting norovirus-like infection. Among the 16 cohorts, 3 were selected for cohort studies. Among those three cohorts, the mean illness rate was 68%. Associations were found between those who fell ill and those who had consumed pasta salad (relative risk [RR] = 2.4; P = 0.0022) and ham sandwiches (RR = 1.8; P = 0.0096). No food handlers reported being sick. No stool samples were provided by individuals who became ill. Environmental and food samples were all negative for causative agents. Although the causative agent was not clearly identified, this investigation raised many concerns about the importance of preventing foodborne transmission of viral gastroenteritis and generated some recommendations for management of similar outbreaks.