Nationwide molecular surveillance of pandemic H1N1 influenza A virus genomes: Canada, 2009.

BACKGROUND: In April 2009, a novel triple-reassortant swine influenza A H1N1 virus ("A/H1N1pdm"; also known as SOIV) was detected and spread globally as the first influenza pandemic of the 21(st) century. Sequencing has since been conducted at an unprecedented rate globally in order to monitor the diversification of this emergent virus and to track mutations that may affect virus behavior. METHODOLOGY/PRINCIPAL FINDINGS: By Sanger sequencing, we determined consensus whole-genome sequences for A/H1N1pdm viruses sampled nationwide in Canada over 33 weeks during the 2009 first and second pandemic waves. A total of 235 virus genomes sampled from unique subjects were analyzed, providing insight into the temporal and spatial trajectory of A/H1N1pdm lineages within Canada. Three clades (2, 3, and 7) were identifiable within the first two weeks of A/H1N1pdm appearance, with clades 5 and 6 appearing thereafter; further diversification was not apparent. Only two viral sites displayed evidence of adaptive evolution, located in hemagglutinin (HA) corresponding to D222 in the HA receptor-binding site, and to E374 at HA2-subunit position 47. Among the Canadian sampled viruses, we observed notable genetic diversity (1.47 x 10⁻³ amino acid substitutions per site) in the gene encoding PB1, particularly within the viral genomic RNA (vRNA)-binding domain (residues 493-757). This genome data set supports the conclusion that A/H1N1pdm is evolving but not excessively relative to other H1N1 influenza A viruses. Entropy analysis was used to investigate whether any mutated A/H1N1pdm protein residues were associated with infection severity; however no virus genotypes were observed to trend with infection severity. One virus that harboured heterozygote coding mutations, including PB2 D567D/G, was attributed to a severe and potentially mixed infection; yet the functional significance of this PB2 mutation remains unknown. CONCLUSIONS/SIGNIFICANCE: These findings contribute to enhanced understanding of Influenza A/H1N1pdm viral dynamics.

Pandemic (H1N1) 2009 outbreak at Canadian Forces cadet camp.

We conducted a case-control study to describe the clinical and epidemiologic characteristics of an outbreak of pandemic (H1N1) 2009 at a Canadian military cadet training center. We found that asthma and obesity confer greater risk for infection. Viral shedding was detected by PCR up to 18 days after symptom onset.

Trends in vaccine-induced immunity to hepatitis B among Canadian street-involved youth.

In Canada, universal and publicly funded hepatitis B immunization programs have been available since 1998 in all provinces and territories. This present study estimates the proportion of having vaccine-induced immunity to hepatitis B virus (HBV) infection and its associated determinants among street-involved youth aged at 15-24 years old in Canada using the data collected by the Enhanced Surveillance of Canadian Street Youth. Vaccine-induced immunity was identified by blood test results of anti-HBc negative and anti-HBs positive. Of the 4,035 participants included in this study, the overall proportion of those with vaccine-induced immunity to HBV was 51.7% during the study period compared to over 90% among the general adolescent population. The proportion of street-involved youth immunized with HBV vaccine increased from 34.7% in 1999 to 64.4% in 2005. Immunity was higher among females (aOR = 1.43, 1.17-1.75) and among those with a reported history of sexually transmitted infection (aOR = 1.30, 1.03-1.63). The proportion of youth with the immunity decreased as age increased (aOR = 0.78, 0.76-0.81, per year increase). Despite an overall increase in the proportion of Canadian street-involved youth with vaccine-induced immunity to HBV, the proportion was still significantly lower than that observed in the general adolescent population. This highlights the need to improve the access to basic health care and the immunization programs to HBV for street-involved youth through creative outreach programs and other multi-faceted approaches.

A population-based ecologic study of inflammatory bowel disease: searching for etiologic clues.

The authors' objective in this study was to determine geographic variations in the incidence of inflammatory bowel disease (IBD), specifically Crohn's disease and ulcerative colitis, in the Canadian province of Manitoba and its association with the sociodemographic, geographic, and disease-related characteristics of the study population. Using the University of Manitoba IBD Epidemiology Database, the authors applied spatial and ecologic techniques to visualize, explore, and model the incidence of Crohn's disease and ulcerative colitis for the period 1990-2001. The study demonstrated marked, statistically significant geographic variability in rates of both Crohn's disease and ulcerative colitis associated with the characteristics of the study population. Incidences of Crohn's disease and ulcerative colitis were observed to be highest among non-Aboriginal persons, persons of high socioeconomic status, persons with the lowest rates of enteric infection, and persons with the highest rates of multiple sclerosis. The observation of an inverse association between IBD incidence and rates of reportable enteric infection at the population level is consistent with the "hygiene hypothesis," which suggests that early exposure to enteric agents affords protection against eventual development of IBD. The positive association between IBD incidence rates and multiple sclerosis suggests that these two chronic, immunologically mediated diseases may have a common environmental etiology. This study underscores the importance of environment in IBD causation.

Enhanced surveillance of non-O157 verotoxin-producing Escherichia coli in human stool samples from Manitoba.

BACKGROUND: Relatively few enhanced surveillance studies have been undertaken to investigate the extent to which verotoxin-producing non-O157 serotypes of Escherichia coli occur in stool samples received for the detection of verotoxin-producing organisms. OBJECTIVES: To describe the prevalence, molecular and epidemiological characteristics, and geographical patterns associated with non-O157 verotoxin-producing E coli (VTEC) in Manitoba. RESULTS: Thirty-two VTEC isolates consisting of 10 serogroups and 13 different serotypes were isolated over a 22-month period. Twenty-three isolates (71.8%) possessed verotoxin-encoding gene stx1 only, five isolates (15.6%) possessed stx2 only, two isolates (6.3%) possessed both stx1 and stx2, and two isolates (6.3%) possessed stx2c. Only three instances of indistinguishable pulsed-field gel electrophoresis patterns were identified. The age of the individuals from whom non-O157 VTEC were isolated ranged from eight months to 87 years. Mean and median ages were 30 and 22 years of age, respectively. Some areas of the province appeared to experience a higher than expected number of non-O157 E coli in comparison with the number of stools that were received from these areas. CONCLUSIONS: The present study demonstrated a large number of infections associated with non-O157 VTEC in Manitoba. Most non-O157 cases appear to result from sporadic infections, and these occur typically in rural areas. Continued enhanced surveillance is necessary to understand the temporal patterns of non-O157 VTEC and the underlying epidemiological factors driving these patterns.

Preventable feto-infant mortality: application of a conceptual framework for perinatal health surveillance to Manitoba perinatal outcomes.

BACKGROUND: Perinatal health surveillance systems have lacked conceptual frameworks to translate data into information for policy and program planning. This paper demonstrates the application of a conceptual framework in the analysis of feto-infant mortality data in the province of Manitoba. METHODS: Fetal and infant deaths were categorized according to a two-dimensional framework of birthweight and age-at-death, and grouped into four broad categories of contributors to perinatal health: Maternal Health, Maternal Care, Newborn Care, and Infant Care. Birth Weight Proportionate Mortality Rates (BWPMR) were calculated for each of the four categories, and preventable "excess" feto-infant mortality was estimated through comparisons to a benchmark sub-population. RESULTS: Between 1985 and 1998, feto-infant mortality declined from 12.3 to 9.8 deaths per 1000 births in Manitoba. Much of this decline occurred in the Newborn Care category; there were only slight declines in deaths attributed to Maternal Health and Infant Care factors. Comparison of the feto-infant mortality rate to the benchmark rate revealed an excess of 3.46 deaths per 1000 births, an "opportunity gap" of 33%. Substantial regional variations in feto-infant mortality rates were observed. SUMMARY: Application of this conceptual framework provided useful information to aid in policy and program planning. As the greatest excess feto-infant mortality was observed in the Maternal Health and Infant Care categories, attention to the broader determinants of health which influence these categories will be required.