Publications by authors named "Marcus Lem"

Background: Climate change is increasing the number and intensity of extreme weather events in many parts of the world. Precipitation extremes have been linked to both outbreaks and sporadic cases of waterborne illness. We have previously shown a link between heavy rain and turbidity to population-level risk of sporadic cryptosporidiosis and giardiasis in a major Canadian urban population.

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Drinking water related infections are expected to increase in the future due to climate change. Understanding the current links between these infections and environmental factors is vital to understand and reduce the future burden of illness. We investigated the relationship between weekly reported cryptosporidiosis and giardiasis (n = 7,422), extreme precipitation (>90th percentile), drinking water turbidity, and preceding dry periods in a drinking water system located in greater Vancouver, British Columbia, Canada (1997-2009) using distributed lag non-linear Poisson regression models adjusted for seasonality, secular trend, and the effect of holidays on reporting.

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Introduction: Intramuscular Immune Serum Globulin (IM ISG) is recommended as post-measles exposure prophylaxis (PEP) when administered within 6days of initial exposure, with variable effectiveness in preventing measles disease. Effectiveness of IM ISG PEP in preventing clinical measles was assessed during a 2014 measles outbreak among a religious-affiliated community in British Columbia, Canada.

Material And Methods: Fifty-five self-reporting measles susceptible contacts were offered exclusively IM ISG PEP within an eligibility period best surmised to be within 6days of initial measles case exposure.

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Objective: To characterize the first-wave epidemiologic features of influenza-like illness (ILI) associated with the novel pandemic A/H1N1 [A(H1N1)pdm09] virus.

Methods: We used generalized linear mixed models (GLMM) to assess risk factors and non-parametric and/or parametric distributions to estimate attack rates, secondary attack rates (SAR), duration of illness, and serial interval during a laboratory-confirmed community outbreak of A(H1N1)pdm09 clustered around on-reserve residents and households of an elementary school in rural British Columbia, Canada, in late April/early May 2009. ILI details were collected as part of outbreak investigation by community telephone survey in early June 2009.

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Article Synopsis
  • A tuberculosis outbreak occurred in a British Columbia community over three years, identified as clonal through MIRU-VNTR genotyping, but traditional contact tracing failed to determine the source.
  • Researchers utilized whole-genome sequencing on 32 outbreak samples and social-network analysis to better understand the outbreak's dynamics, revealing two genetically distinct M. tuberculosis lineages responsible for simultaneous outbreaks.
  • The study indicated that the outbreak was driven by socioenvironmental factors, notably an increase in crack cocaine use, rather than solely by genetic factors, demonstrating the need for comprehensive methods beyond genotyping and contact tracing.
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An association between leukoencephalopathy, a disease of the white matter of the brain, and smoking heroin is well recognized. This paper describes 27 cases of leukoencephalopathy identified in two cities in British Columbia, Canada 2001-2006; the largest number of geographically and temporally defined reported cases in North America.Twenty cases of leukoencephalopathy were identified in and around Vancouver with onset dates December 2001 to July 2003; seven further cases were identified in Victoria September 2005-August 2006.

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Background: In April 2009, an elementary school outbreak of pandemic H1N1 (pH1N1) influenza was reported in a community in northern British Columbia, Canada--an area that includes both non-Aboriginal and Aboriginal residents living on or off a reserve. During the outbreak investigation, we explored the relationship between prior receipt of trivalent inactivated influenza vaccine (TIV) and pH1N1-related illness.

Methods: A telephone survey was conducted from 15 May through 5 June 2009 among households of children attending any school in the affected community.

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Objective: To review the severe acute respiratory syndrome (SARS) infection control practices, the types of exposure to patients with SARS, and the activities associated with treatment of such patients among healthcare workers (HCWs) who developed SARS in Toronto, Canada, after SARS-specific infection control precautions had been implemented.

Methods: A retrospective review of work logs and patient assignments, detailed review of medical records of patients with SARS, and comprehensive telephone-based interviews of HCWs who met the case definition for SARS after implementation of infection control precautions.

Results: Seventeen HCWs from 6 hospitals developed disease that met the case definition for SARS after implementation of infection control precautions.

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The aim of this study was to quantify the level of employment at one-year and to determine potential predictors of future employment among HIV-positive persons on highly active antiretroviral therapy (HAART) in the province of British Columbia. Of the 392 individuals that were initially unemployed at baseline 63 (16.1%) found a job over the subsequent year.

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