Invasive group A streptococcal infection outbreaks of typeemm118 in a long-term care facility, and of type emm74 in the homeless population, Montréal, Quebec.

BACKGROUND: Two invasive group A streptococcus (iGAS) infection outbreaks occurred in Montreal in 2016 and 2017; one in a long-term care facility (typeemm118) and one in the community, primarily involving homeless people (typeemm74). OBJECTIVE: To describe two recent iGAS outbreaks in Montréal and highlight the challenges in dealing with these outbreaks and the need to tailor the public health response to control them. METHODOLOGY: All cases of iGAS were investigated and the isolates were sent to the laboratory foremmtyping. In both outbreaks, cases of superficial group Astreptococcus(GAS) infection were identified, through 1) systematic case detection accompanied by screening for asymptomatic carriers among residents and employees of the long-term care facility and 2) sentinel surveillance among homeless people. Visits were made to community organizations providing homeless services (including shelters) and social networks were analyzed to establish whether there were any links among cases of GAS infection (both invasive and noninvasive) and locations frequented. In both outbreaks, recommendations were made to service providers regarding enhancement of infection prevention and control measures. RESULTS: In the long-term care facility, five cases of typeemm118 iGAS were identified over a 22-month period, one of which resulted in death. All residents were screened and no carriers were identified. Among the employees, 81 (65%) were screened and fourcarriers were identified. Of those, one was a carrier of typeemm118 GAS. All carriers were treated, and subsequent follow-up sampling on three carriers (including the one withemm118) was negative.In the community, 23 cases of typeemm74 iGAS were detected over a 16-month period, four of which resulted in death. Half of the cases (n=12) were described as homeless, and six others were users of services for the homeless. Sentinel surveillance of superficial infections yielded 64 cultures with GAS, chiefly on the skin, including 51 (80%) of typeemm74. An analysis of the social networks revealed the large number and variety of resources for the homeless used by the cases. Visits to the community organizations providing homeless services revealed the heterogeneity and precariousness of some of these services, the difficulties encountered in applying adequate health and hygiene measures, and the high degree of mobility amongst those who use these services. CONCLUSION: The detection and control of iGAS outbreaks in both long-term care establishments and among community organizations providing homeless services are very complex. An outbreak of iGAS can develop in the background over a long time and be easily overlooked despite cases being admitted to the hospital.Emmtyping and systematic research of previous cases of iGAS are essential tools for the detection and characterization of outbreaks. Close cooperation among public health agencies, clinical teams, community organizations and laboratories is essential for proper monitoring and the reduction of GAS transmission in the community and health care settings.

Salmonella Thompson outbreak associated with consumption of chicken shawarma and the usefulness of genome sequencing in the investigation.

BACKGROUND: A sudden increase in Salmonella Thompson (S. Thompson) cases distributed throughout three border regions in the province of Quebec in November 2016 triggered a provincial investigation to identify a common source of contamination and to put the appropriate control measures into place. OBJECTIVE: To report on the outbreak and to describe the use of genomic sequencing to identify the salmonella serotype responsible. METHODS: A descriptive survey of all reported cases of Salmonella serogroup C1 that had occurred between October 1, 2016 and February 15, 2017 was conducted. A case definition was developed. Pulsed field gel electrophoresis supplemented by analyses of genome sequences using the single nucleotide variant phylogenomics method were used to demarcate and manage the outbreak. RESULTS: Eighteen cases of S. Thompson were identified through whole genome sequencing. The onset dates of symptoms for the 16 cases that presented enteric symptoms were November 21-December 2, 2016. Two cases that presented with atypical symptoms were not reported until February 2017. Among the 18 cases, 16 had eaten or probably eaten chicken shawarma at the same restaurant chain and nine of these cases ate it at the same restaurant. In total, five restaurants from this chain, spread throughout three border regions of Quebec, were identified. CONCLUSION: Outbreaks associated with chicken shawarma have been identified in the past. Efforts must be made to ensure that the owners of this type of restaurant know the contamination risk associated with this type of cooking and take the necessary steps to reduce this risk. The use of the genome sequencing method was very useful in defining the outbreak.

Outbreak of Shigella sonnei in Montréal's ultra-Orthodox Jewish community, 2015.

An outbreak of Shigella sonnei that occurred in the ultra-Orthodox Jewish community (UOJC) was the subject of an investigation and response by the Montréal Regional Public Health Department (DRSP), who collaborated with several health and community partners. A total of 27 confirmed cases were reported in this outbreak, which lasted from February to June 2015. The epidemic curve was compatible with a point source with secondary person-to-person transmission. In 11 of the 27 cases, pulsed-field gel electrophoresis (PFGE) analysis of strains found a single PFGE pattern newly identified in Quebec. Almost all strains tested showed resistance to ampicillin and trimethoprim-sulfamethoxazole (TMP/SMX). All the cases resided in Montréal Centre-West. Most of the cases were under 5 years old and attended a daycare centre, an environment recognized to be conducive to the transmission of enteric diseases. DRSP sent timely information to families, daycare and school stakeholders, community partners and synagogues in the UOJC, which helped reduce the transmission of shigellosis in the community.

Shifting dominance of Shigella species in men who have sex with men.

Historically, Shigella sonnei has dominated other Shigella species infection in men who have sex with men (MSM) in Montréal. In early 2010, Toronto reported increased proportions of the more pathogenic S. flexneri, HIV co-infection and MSM in shigellosis cases since 2009. Analytical methods were used to assess whether S. flexneri had dominated Montréal's MSM cases since 2009 and whether changes had occurred in notifications in MSM and HIV-co-infected MSM. S. flexneri increased by 6·7% per month since 2007 and predominated in MSM since 2009 without changes in HIV co-infection or similar shifts in the general population. The results suggest that the surveillance of Shigella species in order to detect species shifts is beneficial for surveillance, given the potential for increased transmission and severity of S. flexneri in HIV-positive MSM.

Pre-exposure rabies prophylaxis for the international traveller: a decision analysis.

To determine for which travellers pre-exposure rabies prophylaxis is indicated, a decision tree-based model has been developed which enables the comparison of one million travellers going to rabies-endemic areas who receive a pre-exposure rabies prophylaxis to one million travellers also going to rabies-endemic areas who are not vaccinated. Using data obtained from a review of the literature, probabilities were assigned to each significant outcome. When numbers were not available, estimates were used and tested with a sensitivity analysis. Routine pre-exposure prophylaxis would prevent 0.054 cases per million adult travellers per month at a cost of 5 billion (thousand million) Canadian dollars. In the worst-case scenario, which concerns children, the cost per case prevented per year of stay would be $275,000 dollars. Our decision analysis leads us to believe that routine pre-exposure prophylaxis given to travellers heading for rabies-endemic regions of the world is not indicated. We conclude that pre-exposure rabies prophylaxis is a medical decision that must be individualized for every traveller and should be particularly considered for children at high risk of being exposed to rabies, who are leaving for a long stay (more than one year) and who will not have rapid access to medical services and rabies immunobiologics.