Publications by authors named "Raymond Sw Tsang"

Article Synopsis
  • Serotype a (Hia) is becoming a significant cause of serious infections in young Indigenous children in the North American Arctic and Sub-Arctic areas.
  • A study compared the presence of Hia in children with respiratory infections from high-incidence regions like Nunavut to low-incidence areas like Southern Ontario.
  • The study found Hia was present in 3.0% of children in Nunavut versus 0.6% in Southern Ontario, indicating ongoing circulation of the bacteria in Northern communities which could potentially lead to more severe outbreaks.
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Background: serotype a (Hia) has recently emerged as an important cause of invasive disease, mainly affecting young Indigenous children. Carriage of is a pre-requisite for invasive disease and reservoir for transmission. To better understand the epidemiology of invasive Hia disease, we initiated a multicentre study of nasopharyngeal carriage among Canadian children.

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Background: A resurgence of syphilis infections has been described in a number of countries including Canada in the last decade.

Methods: This study identified polymerase chain reaction (PCR) positive syphilis cases based on detection of genes (, , and ) in 3,350 clinical specimens obtained from patients in the province of Manitoba, Canada between 2017 and 2020. Patient demographics were obtained from specimen requisition forms.

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Over the past few years, the increase in infectious syphilis outbreaks in major urban centres and remote or rural locations in Canada, often affecting hard-to-reach patient populations, has renewed an interest and urgency in studying the use of point-of-care tests (POCTs) that can provide test results at the time and place of primary health care delivery, obviating the repeat visit necessary with traditional syphilis serology or molecular diagnostic tests. In 2015, the Canadian Public Health Laboratory Network released its first laboratory guideline for the use of POCTs in the diagnosis of syphilis in Canada. Although Canada has no licensed POCT, two POCTs (Syphilis Health Check and the DPP® HIV Syphilis System) have received US Food and Drug Administration (FDA) approval under premarket approval applications.

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Article Synopsis
  • - Since 2002, Canada has implemented meningococcal vaccination programs, leading to a decline in invasive meningococcal disease (IMD), particularly for serogroup C, while also responding to outbreaks with vaccines for serogroup B.
  • - Between 2012 and 2019, there were 983 reported cases of IMD, with the highest incidence in infants under one year and serogroup B being the most prevalent strain during this period.
  • - Recent trends show a concerning rise in serogroup W infections linked to a more virulent strain (ST-11 CC), indicating a shift in the epidemiological landscape of IMD in Canada.
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Background: Syphilis is a sexually transmitted disease that can have atypical clinical presentations. Conventional laboratory tests to confirm the diagnosis are not rapid enough to affect clinical decision on treatment and contact tracing. Rapid point-of-care tests (POCT) can be useful for control of infectious diseases; however, no POCT for syphilis detection is currently available in Canada.

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Article Synopsis
  • - The introduction of the Hib conjugate vaccine has shifted the landscape of invasive infections, leading to more cases caused by non-typeable and non-Hib strains.
  • - Researchers identified nine invasive serotype e (Hie) strains in British Columbia that completely lack fucose operon genes, mainly from blood cultures of three female and six male patients between 2011 and 2018.
  • - Despite the genetic deletion, these fucose operon-negative Hie strains maintained high similarity to the most common strains in the area, suggesting it did not hinder their ability to spread or cause disease.
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Background: Serogroup B Neisseria meningitidis (MenB) has always been a major cause of invasive meningococcal disease (IMD) in Canada. With the successful implementation of a meningitis C conjugate vaccine, the majority of IMD in Canada is now caused by MenB.

Objective: To investigate IMD case isolates in Atlantic Canada from 2009 to 2013.

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Syphilis, caused by the bacterium Treponema pallidum subsp. pallidum, is an infection recognized since antiquity. It was first reported at the end of the 15th century in Europe.

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Treponema pallidum subsp. pallidum and/or its nucleic acid can be detected by various methods such as microscopy, rabbit infectivity test or polymerase chain reaction (PCR) tests. The rabbit infectivity test for T.

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Before the introduction of the conjugate vaccine, Haemophilus influenzae serotype b (Hib) was the leading cause of bacterial meningitis in children. Although successful in reducing Hib cases, the vaccine confers no protection against other serotypes of H influenzae, such as a (Hia), or f (Hif). The emergence of invasive disease caused by non-Hib in northwestern Ontario (38 cases between 2002 and 2008) with predominance of Hia was previously reported by the authors.

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Background: Serogroup C meningococcal disease has been endemic in Canada since the early 1990s, with periods of hyperendemic disease documented in the past two decades. The present study characterized invasive serogroup C meningococci in Canada during the period from 2002 to 2009.

Methods: Serogroup C meningococci were serotyped using monoclonal antibodies.

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Laboratory diagnosis of syphilis has undergone major changes in the past decade with the introduction of immunoassays and recombinant Treponema pallidum antigens as screening tools for syphilis infection. To address this change in laboratory practice, a national syphilis laboratory working group was established with members from the Public Health Agency of Canada, provincial public health laboratories across the country as well as sexually transmitted infection researchers, clinicians and epidemiologists. This working group aims to examine how the use of newer immunoassays will affect syphilis diagnosis, surveillance and disease management.

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Article Synopsis
  • Researchers amplified and sequenced the quinolone resistance-determining regions of gyrA and parC in Haemophilus parainfluenzae strains.
  • Similar to another bacteria, Haemophilus influenzae, quinolone resistance in H. parainfluenzae is linked to mutations in these genes.
  • The study emphasizes the significance of understanding these mutations for tracking antibiotic resistance.
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Introduction: Serogroup A Neisseria meningitidis has repeatedly caused epidemics of invasive meningococcal disease (IMD) in developing nations since the 1960s. The present study is the first detailed study of serogroup A bacteria isolated in Canada.

Methods: Thirty-four serogroup A meningococcal isolates collected from individuals with IMD in Canada between 1979 and 2006 were characterized by serology and multilocus sequence typing of seven housekeeping enzyme genes and genes encoding three outer membrane protein antigens.

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Three group B Neisseria meningitidis isolates, recovered from meningococcal disease cases in Canada and typed as B:2c:P1.5, were characterized. Multilocus sequence typing showed that all three isolates were related because of an identical sequence type (ST) 573.

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The relative frequency of serogroups of Neisseria meningitidis associated with meningococcal disease in Canada during the period January 1, 1999 to June 30, 2001 was examined. Of the 552 strains of N meningitidis collected from clinical specimens of normally sterile sites, 191 (34.6%), 276 (50.

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Guillain-Barre syndrome is a postinfectious disorder caused by an aberrant immune response to an infectious pathogen, resulting in an autoimmune disease. As with other autoimmune diseases of infectious nature, the intricate balance of the numerous factors involved in the immune response may determine the outcome of the interaction between the microbe and host. Recent studies focusing on the role of cytokines and its network of related mediators and receptors suggest that any imbalance may make a significant contribution to the outcome of the infectious disease process.

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