The impact of pertussis vaccine programme changes on pertussis disease burden in Manitoba, 1992-2017-an age-period-cohort analysis.

BACKGROUND: Changes to pertussis vaccination programmes can have impacts on disease burden that should be estimated independently from factors such as age- and period-related trends. We used age-period-cohort (APC) models to explore pertussis incidence in Manitoba over a 25-year period (1992-2017). METHODS: We identified all laboratory-confirmed cases of pertussis from Manitoba's Communicable Diseases Database and calculated age-standardized incidence rates. We used APC models to investigate trends in pertussis incidence. RESULTS: During the study period, 2479 cases were reported. Age-standardized rates were highest during a large outbreak in 1994 (55 cases/100 000 person-years), with much lower peaks in 1998, 2012 and 2016. We saw strong age and cohort effects in the APC models, with a steady decrease in incidence with increasing age and increased risk in the cohort born between 1980 and 1995. CONCLUSIONS: The highest risk for pertussis was consistently in young children, regardless of birth cohort or time period. The 1981 programme change to an adsorbed whole-cell pertussis vaccine with low effectiveness resulted in reduced protection in the 1981-95 birth cohort and contributed to the largest outbreak of disease during the 25-year study period.

Pertussis vaccine effectiveness and duration of protection - A systematic review and meta-analysis.

A comprehensive review of observational pertussis vaccine effectiveness (VE) studies is needed to update gaps from previous reviews. We conducted a systematic review of VE and duration of protection studies for the whole-cell (wP) and acellular (aP) pertussis vaccines and conducted a formal meta-analysis using random effects models. Evidence continues to suggest that receipt of any pertussis vaccine confers protection in the short-term against disease although this protection wanes rapidly for aP vaccine. We detected significant heterogeneity in pooled estimates due, in part, to factors such as bias and confounding which may be mitigated by study design. Our review of possible sources of heterogeneity may help interpretation of other VE studies and aid design decisions in future pertussis VE research.

Comparing the Ecological Niches of Chlamydial and Gonococcal Infections in Winnipeg, Canada: 2007-2016.

BACKGROUND: Previous studies have shown substantial differences in geographic clustering of sexually transmitted infections (STI), such as chlamydia (CT) and gonorrhea (NG), conditional on epidemic phase. Chlamydia and NG have recently shown resurgent epidemiology in the northern hemisphere. This study describes the recent epidemiology of CT and NG in Winnipeg, Canada, combining traditional surveillance tools with place-based analyses, and comparing the ecological niches of CT and NG, in the context of their evolving epidemiology. METHODS: Data were collected as part of routine public health surveillance between 2007 and 2016. Secular trends for CT and NG, and CT/NG coinfection were examined. Gini coefficients and population attributable fractions explored the distribution, and concentration of infections over time and space. RESULTS: Rates of CT increased from 394.9/100,000 population to 476.2/100,000 population from 2007 to 2016. Gonorrhea rates increased from 78.0/100,000 population to 143.5/100,000 population during the same period. Each pathogen had its own ecological niche: CT was widespread geographically and socio-demographically, while NG was clustered in Winnipeg's inner-core. CT/NG co-infections had the narrowest space and age distribution. NG was shown to be undergoing a growth phase, with clear signs of geographic dispersion. The expansion of NG resembled the geographic distribution of CT. CONCLUSIONS: We demonstrated that NG was experiencing a growth phase, confirming theoretical predictions of geographic dispersion during a growth phase. During this phase, NG occupied similar geographic spaces as CT. Knowledge of different ecological niches could lead to better targeting of resources for subpopulations vulnerable to STIs.

Epidemiology of incident chlamydia and gonorrhoea infections and population attributable fractions associated with living in the inner-core of Winnipeg, Canada.

Population attributable fractions help to convey public health significance of differential disease risk for chlamydia and gonorrhoea. Geographical residence serves as a useful proxy for complex processes creating ill health. Using population-based data, Poisson regression models were used to examine factors associated with chlamydia and gonorrhoea incidence. Population attributable fractions due to residency in the Winnipeg Health Region's inner-core were determined for chlamydia/gonorrhoea infections among 15-59-year olds (2005-2013), stratified by age group. For both chlamydia and gonorrhoea, it was found that the 15-24-year old age group had the highest incidence rates. There was also a stronger association between residency in the inner-core and incidence for gonorrhoea, compared to chlamydia. Overall, 24% (95% CI: 12-34%) of chlamydia infections were attributable to residency in the inner-core, compared to 46% (95% CI: 35-54%) for gonorrhoea ( p < .05). Within chlamydia/gonorrhoea, no statistically significant differences in population attributable fraction were observed by age group. The conclusion was that a concentration of efforts towards inner-core residents with gonorrhoea infections may result in a relatively larger decrease in incidence.

Infectious syphilis in women: what's old is new again?

The aim of this study was to examine trends in infectious syphilis epidemiology among women in Winnipeg, Canada. A descriptive study of syphilis among Winnipeg residents between 2003 and 30 June 2015 was undertaken. Adjusted rate ratios (ARR) and 95% confidence intervals (95%CI) from Poisson regression analyses are reported. Characteristics of men and women were compared using logistic regression, with adjusted odds ratios (AOR) reported. Between 2014 and 2015, the rate of syphilis was 1.7/100,000, representing a five-fold increase since 2006-2013. All cases have been heterosexual, 90% 20-39 years of age, and 59% living in Winnipeg's inner core. Approximately 24% were pregnant at diagnosis; no cases of congenital syphilis have been reported. Compared to men, women were more likely to report alcohol use (AOR: 3.8, 95% CI: 1.2-11.9) and co-infection with chlamydia (AOR: 5.0, 95% CI: 1.1-22.9). In conclusion, the rates of infectious syphilis are increasing among women. Prenatal screening and education for inner-core women and the health care providers serving them should be prioritized.

Canadian medical students' perceptions of public health education in the undergraduate medical curriculum.

PURPOSE: To understand the perceptions and attitudes of Canadian medical students toward their undergraduate medical public health curriculum and to identify student suggestions and priorities for curriculum change. METHOD: Five focus groups of 11 or 12 medical students from all years of medical school were recruited at McMaster University Faculty of Health Sciences, Université de Sherbrooke Faculty of Medicine and Health Sciences, University of Toronto Faculty of Medicine, University of Manitoba Faculty of Medicine, and University of British Columbia Faculty of Medicine between February and April 2006. A professional facilitator was hired to conduct the focus groups using a unique, computer-based facilitation system. Questions in both the focus group and an accompanying survey sought to determine medical students' understanding and exposure to public health and how this impacted their attitudes and choices toward careers in the public health medical specialty of community medicine. The transcripts were independently reviewed and analyzed by each of the authors to identify themes. RESULTS: Four major themes related to students' desired curriculum change were identified: (1) poor educational experiences in public health courses, (2) lack of positive role models, especially exposure to community medicine specialists, (3) emphasis on statistics and epidemiology, and (4) negative attitudes toward public health topics. CONCLUSIONS: Students are disillusioned, disengaged, and disappointed with the public health curriculum currently being provided at the Canadian medical schools studied. Many medical students would prefer a public health curriculum that is more challenging and has more applied field experience and exposure to public health physician role models.

Assessing Canadian medical students' familiarity with and interest in pursuing a career in community medicine.

OBJECTIVES: Following the SARS outbreak, large gaps in the public health workforce have been identified. This study sought to understand the perceptions and attitudes of Canadian medical students with regard to public health to determine how this impacted their choice towards a career in Community Medicine (CM). METHODS: Five focus groups of 11-12 medical students from all years were recruited at McMaster University, Université de Sherbrooke, University of Toronto, University of Manitoba and the University of British Columbia. A professional facilitator was hired to conduct the focus groups using a unique computer-based facilitation system. Questions in both the focus group and an accompanying survey sought to determine medical students' understanding and exposure to public health and how this impacted their attitude and choice towards a career in community medicine. The transcripts were independently reviewed and analyzed by each of the authors to identify themes. RESULTS: Four major themes related to choosing Community Medicine as a career were identified: 1) poor understanding of the role of Community Medicine specialists in public health practice, 2) perceived lack of clinical work and relevance of public health to clinical practice, 3) perceived lack of exclusivity of Community Medicine specialty, 4) incentives and disincentives to pursuing Community Medicine. CONCLUSION: Better education of students on the role of CM specialists through increasing exposure to role models and demystifying inaccurate perceptions of CM through integration of public health with clinical medicine may potentially increase medical student entry into Community Medicine.

A common CD4 gene variant is associated with an increased risk of HIV-1 infection in Kenyan female commercial sex workers.

BACKGROUND: It has been predicted that CD4 C868T, a novel CD4 single-nucleotide polymorphism (SNP) that has been found to be highly prevalent among Africans, changes the tertiary structure of CD4, which may alter susceptibility to human immunodeficiency virus (HIV) infection. METHODS: Participants were from a Kenyan cohort and included 87 uninfected and 277 HIV-1-infected individuals. DNA sequencing was used to determine CD4 genotype. A2.01 cells expressing similar levels of either wild-type CD4 or CD4-Trp240 as well as peripheral blood mononuclear cells from uninfected donors were infected with HIV-1(IIIB) or a Kenyan primary HIV-1 isolate. HIV-1 p24 enzyme-linked immunosorbent assay was used to determine the outcome of infection. RESULTS: CD4 C868T was found to be significantly more prevalent among HIV-1-infected participants than among HIV-1-uninfected participants (P = .002), and C868T was associated with an increased incidence of HIV-1 infection as well (P = .005, log-rank test; P = .009, Wilcoxon test), with an odds ratio of 2.49 (P = .009). Both in vitro and ex vivo models demonstrated a significant association between CD4 C868T and susceptibility to HIV-1 infection (P < .001 and P = .003, respectively). CONCLUSION: Overall, the present study found a strong correlation between CD4 C868T and increased susceptibility to HIV-1 infection. Given the high prevalence of both HIV infection and CD4 C868T in African populations, the effect of this SNP on the epidemic in Africa could be dramatic.

Inadequate prenatal care and its association with adverse pregnancy outcomes: a comparison of indices.

BACKGROUND: The objectives of this study were to determine rates of prenatal care utilization in Winnipeg, Manitoba, Canada from 1991 to 2000; to compare two indices of prenatal care utilization in identifying the proportion of the population receiving inadequate prenatal care; to determine the association between inadequate prenatal care and adverse pregnancy outcomes (preterm birth, low birth weight [LBW], and small-for-gestational age [SGA]), using each of the indices; and, to assess whether or not, and to what extent, gestational age modifies this association. METHODS: We conducted a population-based study of women having a hospital-based singleton live birth from 1991 to 2000 (N = 80,989). Data sources consisted of a linked mother-baby database and a physician claims file maintained by Manitoba Health. Rates of inadequate prenatal care were calculated using two indices, the R-GINDEX and the APNCU. Logistic regression analysis was used to determine the association between inadequate prenatal care and adverse pregnancy outcomes. Stratified analysis was then used to determine whether the association between inadequate prenatal care and LBW or SGA differed by gestational age. RESULTS: Rates of inadequate/no prenatal care ranged from 8.3% using APNCU to 8.9% using R-GINDEX. The association between inadequate prenatal care and preterm birth and LBW varied depending on the index used, with adjusted odds ratios (AOR) ranging from 1.0 to 1.3. In contrast, both indices revealed the same strength of association of inadequate prenatal care with SGA (AOR 1.4). Both indices demonstrated heterogeneity (non-uniformity) across gestational age strata, indicating the presence of effect modification by gestational age. CONCLUSION: Selection of a prenatal care utilization index requires careful consideration of its methodological underpinnings and limitations. The two indices compared in this study revealed different patterns of utilization of prenatal care, and should not be used interchangeably. Use of these indices to study the association between utilization of prenatal care and pregnancy outcomes affected by the duration of pregnancy should be approached cautiously.

Social inequalities in use of prenatal care in Manitoba.

OBJECTIVE: Analysis of regional variations in use of prenatal care to identify individual-level and neighbourhood-level determinants of inadequate prenatal care among women giving birth in the province of Manitoba. METHODS: Data were obtained from Manitoba Health administrative databases and the 1996 Canadian Census. An index of prenatal care use was calculated for each singleton live birth from 1991 to 2000 (N = 149,291). Births were geocoded into 498 geographic districts, and a spatial analysis was conducted, consisting of data visualization, spatial clustering, and data modelling using Poisson regression. RESULTS: We found wide variation in rates of inadequate prenatal care across geographic areas, ranging from 1.1% to 21.5%. Higher rates of inadequate care were found in the inner-city of Winnipeg and in northern Manitoba. After adjusting for individual characteristics, the highest rates of inadequate prenatal care were among women living in neighbourhoods with the lowest average family income, the highest proportion of the population who were unemployed, the highest rates of recent immigrants, the highest percentage of the population reporting Aboriginal status, the highest percentage of single parent families, the highest percentage of the population with fewer than nine years of education, and the highest rates of women who smoked during pregnancy. CONCLUSION: Social inequalities exist in the use of prenatal care among Manitoba women, despite there being a universally funded health care system. Regional disparities in rates of inadequate prenatal care emphasize the need for further research to determine specific risk factors for inadequate prenatal care in socioeconomically disadvantaged neighbourhoods, followed by provision of effective targeted services.

Conventional and molecular epidemiology of tuberculosis in Manitoba.

BACKGROUND: To describe the demographic and geographic distribution of tuberculosis (TB) in Manitoba, thus determining risk factors associated with clustering and higher incidence rates in distinct subpopulations. METHODS: Data from the Manitoba TB Registry was compiled to generate a database on 855 patients with tuberculosis and their contacts from 1992-1999. Recovered isolates of M. tuberculosis were typed by IS6110 restriction fragment length polymorphisms. Bivariate and multivariate logistic regression models were used to identify risk factors involved in clustering. RESULTS: A trend to clustering was observed among the Canadian-born treaty Aboriginal subgroup in contrast to the foreign-born. The dominant type, designated fingerprint type 1, accounts for 25.8% of total cases and 75.3% of treaty Aboriginal cases. Among type 1 patients residing in urban areas, 98.9% lived in Winnipeg. In rural areas, 92.8% lived on Aboriginal reserves. Statistical models revealed that significant risk factors for acquiring clustered tuberculosis are gender, age, ethnic origin and residence. Those at increased risk are: males (p < 0.05); those under age 65 (p < 0.01 for each age subgroup); treaty Aboriginals (p < 0.001), and those living on reserve land (p < 0.001). CONCLUSION: Molecular typing of isolates in conjunction with contact tracing data supports the notion of the largest ongoing transmission of a single strain of TB within the treaty-status population of Canada recorded to date. This data demonstrates the necessity of continued surveillance of countries with low prevalence of the disease in order to determine and target high-risk populations for concentrated prevention and control measures.

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.