Retrospective Review of Prenatal Gonorrhea and Chlamydia Screening in Alberta: 2018-2022

A retrospective 5-year province-wide evaluation of prenatal Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT) screening in Alberta, Canada, was carried out to assess compliance with the provincial recommendations for universal prenatal screening as a prevention for neonatal ophthalmia. Screening generally improved across the province each year, 82.1% in 2018 and reaching 87.3% in 2022. Women in the age group under 25 years were the most likely to not have the recommended first-trimester screening and demonstrated the highest prevalence of GC and CT infections. The results of this investigation demonstrate that continued improvements are needed to achieve universal prenatal GC/CT screening in Alberta.

Evaluation and comparison of risk-based and universal prenatal HCV screening programs in Alberta, Canada

BACKGROUND & AIMS

Canadian clinical practice guidelines currently recommend risk-based screening for HCV in pregnant individuals. However, no provinces or territories have ever compared the effectiveness of risk-based vs. universal screening for the prenatal diagnosis of HCV. We aimed to evaluate and compare HCV screening programs after implementing a universal population-level pilot program among prenatal patients in Alberta, Canada.

METHODS

The Alberta Prenatal Screening Program for Select Communicable Diseases was amended to include universal HCV antibody screening. Cohorts of pregnant individuals screened for HCV through risk-based or universal programs were generated over 1-year periods. HCV screening rates and prevalence were analyzed and compared between cohorts to evaluate the effectiveness of screening methods. Social and demographic risk factors for HCV-positive individuals were compared between screening cohorts to identify which populations may be overlooked with risk-based guidelines.

RESULTS

HCV antibody screening rates were 11.9% and 99.9% among pregnant individuals in the risk-based and universal cohorts, respectively. HCV prevalence among the cohorts was 0.07% and 0.11% (difference = 0.04%, p = 0.032), with an average of 21 additional HCV-positive pregnant individuals identified annually with universal screening. HCV-positive pregnant patients diagnosed through universal screening were more likely to engage in high-risk sexual behaviours/sex work compared to those diagnosed through risk-based screening (47.6% vs. 12.5%, respectively p = 0.035), suggesting that these high-risk cases are being missed by risk-based screening.

CONCLUSIONS

Universal HCV screening diagnoses significantly higher numbers of pregnant individuals infected with HCV compared to risk-based screening. Universal HCV screening or amending risk-based guidelines to incorporate more proxy variables for risk factors should be considered to improve prenatal HCV screening guidelines in Canada and help achieve HCV elimination in the next decade.

IMPACT AND IMPLICATIONS

HCV is a bloodborne pathogen that can cause severe liver disease and be vertically transmitted from a mother to her baby during pregnancy. Pregnant individuals in Alberta are currently only tested for HCV if they disclose engaging in activities that put them at risk of acquiring the infection (risk-based screening). Using a population-wide universal prenatal HCV screening program, our work shows that testing based on patient disclosed risk alone leads to the significant underdiagnosis of HCV in pregnant individuals and suggests individuals engaging in sex work or risky sexual behaviours are being overlooked by the current risk-based program. Our outcomes represent the first province-wide study to evaluate and compare prenatal HCV risk-based and universal screening programs in Canada and provide evidence to support the update of prenatal HCV screening policies across the country and in similar jurisdictions.

Prevalence of syphilis coinfection in hepatitis C virus positive prenatal patients from Alberta during a pilot routine screening program

BACKGROUND: Alberta routinely screens pregnant patients for select communicable diseases. Hepatitis C virus (HCV) was added to the prenatal screening panel as part of a provincial pilot program in February 2020. This retrospective cross-sectional study aimed to characterize the prevalence of syphilis coinfections in prenatal patients infected with HCV following implementation of the pilot program.METHODS: Routine prenatal HCV and syphilis testing data were extracted from the Public Health Laboratory Information System over a 21-month period. HCV positivity was defined as HCV enzyme immunoassay (EIA) reactive with detected HCV ribonucleic acid (RNA) following molecular confirmation, and positive results were examined for syphilis coinfections. All patients reactive on a syphilis EIA and confirmatory Treponema pallidum particle agglutination (TPPA) or follow-up rapid plasma reagin (RPR) test were considered positive for syphilis. Descriptive statistics for coinfected patients were analyzed. RESULTS: Eighty-seven prenatal patients were identified to be positive for HCV. Of those, 19 (21.8%) were reactive on the syphilis EIA and 17 (19.5%) had confirmed infections with the TPPA or RPR tests. For HCV/syphilis coinfected patients, the majority resided in metropolitan regions (64.6%), were from the lowest income quintile neighbourhoods (47.1%) and had previously tested positive for HCV (82.4%) and syphilis (64.6%) at the public health laboratory. CONCLUSIONS: The prevalence of syphilis coinfections in prenatal patients infected with HCV is high in Alberta. HCV/syphilis coinfection prevalence should be further investigated in other jurisdictions and prenatal cohorts to better understand testing and treatment options for prevention of congenital transmission.

Examination of Care Milestones for Preventing Congenital Syphilis Transmission Among Syphilis-Infected Pregnant Women in Alberta, Canada: 2017-2019

BACKGROUND

An infectious syphilis outbreak in Alberta has resulted in increased congenital syphilis (CS) cases. To shed light on potential risk factors, we used administrative data sets to examine care milestones for the prevention of CS among pregnant women diagnosed with syphilis, as well as correlates of women giving birth to infants with CS.

METHODS

Provincial administrative databases were used to identify and describe pregnant women diagnosed with any stage of infectious or noninfectious syphilis who gave birth in Alberta between January 1, 2017, and December 31, 2019. Data on prenatal care, syphilis screening, and syphilis medication dispensation were used to evaluate the care milestones. Clinical care and maternal demographics were assessed using logistic and linear regression analyses to determine correlates for missed care milestones or a newborn outcome of CS.

RESULTS

Of 182 syphilis-infected pregnant women, 63 (34.6%) delivered a newborn with CS. Overall, in the first trimester, 136 (75.1%) women had a health care visit, 72 (39.6%) had a prenatal care visit, 71 (39.0%) were screened for syphilis, and 44 (24.2%) were treated. Gestational time to treatment initiation (adjusted odds ratio, 1.04; 95% confidence interval, 1.02-1.06) and older maternal age at diagnosis (adjusted odds ratio: 1.28, 95% confidence interval, 1.08-1.50) were independently associated with CS outcomes. No variables were found to be independently associated with a health care visit, prenatal screening, or initiation of treatment.

CONCLUSIONS

Although nearly two-thirds of CS cases were prevented, there remained missed opportunities in the prevention of CS. Early treatment, which relies on timely access to prenatal care and screening, was the most important for the prevention of CS.

Seropositivity to SARS-CoV-2 in Alberta, Canada in a post-vaccination period (March 2021-July 2021)

BACKGROUND

The COVID-19 pandemic has necessitated the need to rapidly make public health decisions. We systematically evaluated SARS-CoV-2 seropositivity to understand local COVID-19 epidemiology and support evidence-based public health decision making.

METHODS

Residual blood samples were collected for SARS-CoV-2 receptor binding domain (RBD) IgG testing over a 1-5 day period monthly from 26 February 2021-9 July 2021 from six clinical laboratories across the province of Alberta, Canada. Monthly crude and adjusted (for age and gender) seropositivity were calculated. Results were linked to provincial administrative, laboratory, and vaccine databases.

RESULTS

60,632 individual blood samples were tested. Vaccination data were available for 98.8% of samples. Adjusted RBD IgG positivity rose from 11.9% (95% confidence interval [CI] 11.9-12.0%) in March 2021 to 70.2% (95% CI 70.2-70.3%) in July 2021 (p < .0001). Seropositivity rose from 9.4% (95% CI 9.3-9.4%) in March 2021 to 20.2% (95% CI 20.1-20.2%) in July 2021 in unvaccinated Albertans. Unvaccinated seropositive individuals were from geographic areas with significantly (p < .001) lower median household income, lower proportion of married/common-law relationships, larger average household size and higher proportions of visible minorities compared to seronegative unvaccinated individuals. In July 2021, the age groups with the lowest and highest seropositivity in unvaccinated Albertans were those ≥80 years (12.0%, 95% CI 5.3-18.6%) and 20-29 years (24.2%, 95% CI 19.6-28.8%), respectively. Of seropositive unvaccinated individuals, 50.2% (95% CI 45.9-54.5%) had no record of prior SARS-CoV-2 molecular testing.

CONCLUSIONS

Longitudinal surveillance of SARS-CoV-2 seropositivity with data linkage is valuable for decision-making during the pandemic.

Identifying gaps in the treatment of hepatitis C in patients co-infected with HIV in Edmonton, Alberta

INTRODUCTION

With the availability of direct-acting antivirals, Hepatitis C (HCV) is now considered a treatable disease. Patients who are co-infected with human immunodeficiency virus (HIV) and HCV represent an ideal patient population to treat for HCV, as (1) patients are routinely taking medication for HIV, and therefore would be able to complete HCV drug regimens, and (2) HIV infection has been shown to increase HCV disease progression.

OBJECTIVE

We sought to determine the occurrence of HCV co-infection among HIV patients in our provincial cohort, determine whether they received treatment for HCV, and identify currently viremic patients who can be linked to care.

MATERIALS AND METHODS

HCV laboratory testing data (HCV antibody and HCV RNA) and HCV medication dispensation data was collected for all HIV positive patients. Current and previous HCV infection and treatment was assessed. Chart reviews were conducted for HCV viremic patients to assess their HIV care and social determinants.

RESULTS

Of the 2417 HIV positive patients, 392 (16.2%) were identified as being co-infected with HCV. 198 (50.5%) of the HIV-HCV co-infected patients received HCV treatment and 232 (59.2%) were not viremic on the most recent HCV RNA test. 99 (69.2%) had a suppressed HIV infection suggesting they are active in their HIV care and good candidates for HCV treatment.

CONCLUSION

Despite the availability of direct-acting antivirals, many patients who are co-infected with HIV and HCV are not being treated for HCV. Routine surveillance of HIV-HCV co-infected patients could improve HCV treatment rates in a high-risk population.

Pre-Vaccine Positivity of SARS-CoV-2 Antibodies in Alberta, Canada during the First Two Waves of the COVID-19 Pandemic

We systematically evaluated SARS-CoV-2 IgG positivity in a provincial cohort to understand the local epidemiology of COVID-19 and support evidence-based public health decisions. Residual blood samples were collected for serology testing over 5-day periods monthly from June 2020 to January 2021 from six clinical laboratories across the province of Alberta, Canada. A total of 93,993 individual patient samples were tested with a SARS-CoV-2 nucleocapsid antibody assay with positives confirmed using a spike antibody assay. Population-adjusted SARS-CoV-2 IgG seropositivity was 0.92% (95% confidence interval [CI]: 0.91 to 0.93%) shortly after the first COVID-19 wave in June 2020, increasing to 4.63% (95% CI: 4.61 to 4.65%) amid the second wave in January 2021. There was no significant difference in seropositivity between males and females (1.39% versus 1.27%; P = 0.11). Ages with highest seropositivity were 0 to 9 years (2.71%, 95% CI: 1.64 to 3.78%) followed by 20 to 29 years (1.58%, 95% CI: 1.12 to 2.04%), with the lowest rates seen in those aged 70 to 79 (0.79%, 95% CI: 0.65 to 0.93%) and >80 (0.78%, 95% CI: 0.60 to 0.97%). Compared to the seronegative group, seropositive patients inhabited geographic areas with lower household income ($87,500 versus $97,500; P < 0.001), larger household sizes, and higher proportions of people with education levels of secondary school or lower, as well as immigrants and visible minority groups (all P < 0.05). A total of 53.7% of seropositive individuals were potentially undetected cases with no prior positive COVID-19 nucleic acid test (NAAT). Antibodies were detectable in some patients up to 9 months post positive NAAT result. This seroprevalence study will continue to inform public health decisions by identifying at-risk demographics and geographical areas. IMPORTANCE Using SARS-CoV-2 serology testing, we assessed the proportion of people in Alberta, Canada (population 4.4 million) positive for COVID-19 antibodies, indicating previous infection, during the first two waves of the COVID-19 pandemic (prior to vaccination programs). Linking these results with sociodemographic population data provides valuable information as to which groups of the population are more likely to have been infected with the SARS-CoV-2 virus to help facilitate public health decision-making and interventions. We also compared seropositivity data with previous COVID-19 molecular testing results. Absence of antibody and molecular testing were highly correlated (95% negative concordance). Positive antibody correlation with a previous positive molecular test was low, suggesting the possibility of mild/asymptomatic infection or other reasons leading individuals from seeking medical attention. Our data highlight that the true estimate of population prevalence of COVID-19 is likely best informed by combining data from both serology and molecular testing.

Distribution of HPV genotypes among women with abnormal cytology results in Alberta, Canada

BACKGROUND

Persistent infection with a subset of human papillomavirus (HPV) genotypes can cause abnormal cytology and invasive cervical cancer. This study examines the circulating HPV genotype strains in a local population of the province of Alberta (a largely unvaccinated population) to establish baseline frequency of vaccine and non-vaccine genotypes causing abnormal cervical cytology.

METHOD

Remnant liquid-based cytology specimens from the Alberta Cervical Cancer Screening Program (March 2014-January 2016) were examined. Only specimens from women who had a cytology grading of atypical squamous cells of undetermined significance or higher were included. HPV genotype was determined for all samples, and results were stratified by demographics and cytology results.

RESULTS

Forty-four unique HPV genotypes were identified from 4,794 samples. Of the 4,241 samples with a genotype identified, the most common genotypes were HPV 16, 18, 31, and 51, with 1,599 (37.7%), 441 (12.2%), 329 (7.8%), and 354 (8.4%), respectively. HPV9 vaccine genotypes made up 73.2% of these genotyped samples. Compared with specimens in which HPV9 vaccine genotypes were not detected, those with a genotype covered by the HPV9 vaccine were from younger women (33 [interquartile range {IQR] 28 to 42] y versus 40 [IQR 32 to 51] y; p < 0.00001).

CONCLUSIONS

The baseline distribution of HPV genotypes in this largely unvaccinated population indicates that the HPV9 vaccine provides good protection from high-risk HPV infections. Determining the frequency of genotypes causing abnormal cytology in this population post-vaccine implementation will be important to assess efficacy of vaccination and monitor for any potential genotype replacement.

A low-cost initiative to reduce duplicate hepatitis B virus serological testing

Background

Currently, multiple clinical laboratories provide serological testing for hepatitis B virus (HBV) in Alberta, Canada. Concerns were raised regarding single serology specimens having duplicate testing performed during the specimen referral process from one laboratory to another. In an attempt to reduce duplicate testing for anti-HBs and HBsAg markers, we implemented a stamp on paper requisitions to identify if testing had already been performed on referred specimens. We aimed to determine the number of duplicate tests and cost of duplicate testing pre- and post-stamp implementation.

Study design

The requisition stamp was implemented between May and August 2016. HBV serology testing results from two clinical laboratories between January 01, 2015 and December 31, 2017 (n ​= ​803,637) were examined. The number of tests performed on the same individual within a 3-day window was identified and the associated costs were determined.

Results

After stamp implementation, duplicated HBsAg and anti-HBs tests decreased from 20.8% (n ​= ​28,545) and 18.4% (n ​= ​20,151) to 3.7% (n ​= ​4,604) and 2.5% (n ​= ​2,593), respectively. This represented an estimated annual savings of $86,427 and $82,522 CAD in supply costs for HBsAg and anti-HBs tests, respectively.

Conclusions

The requisition stamp initiative was effective in reducing the number of duplicate tests performed between two laboratory sites. This low-cost intervention could be applied to other testing situations, including other highly duplicated serological markers, which may have broad reaching cost-saving effects for laboratory testing.

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We describe a low-cost, low-tech method to reduce duplicate serology testing.

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We decreased redundant testing from 20% to 3% among all HBsAg and anti-HBs testing.

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Applying this strategy to other high-volume tests could realize significant savings.

Evaluation of Six Commercial Mid- to High-Volume Antibody and Six Point-of-Care Lateral Flow Assays for Detection of SARS-CoV-2 Antibodies

Coronavirus disease (COVID) serological tests are essential to determine the overall seroprevalence of a population and to facilitate exposure estimates within that population. We performed a head-to-head assessment of enzyme immunoassays (EIAs) and point-of-care lateral flow assays (POCTs) to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies. Demographics, symptoms, comorbidities, treatment, and mortality of patients whose sera were used were also reviewed. Six EIAs (Abbott, Affinity, Bio-Rad, DiaSorin, Euroimmun, and Roche) and six POCTs (BTNX, Biolidics, Deep Blue, Genrui, Getein BioTech, and Innovita) were evaluated for the detection of SARS-CoV-2 antibodies in known COVID-19-infected individuals. Sensitivity of EIAs ranged from 50 to 100%, with only four assays having overall sensitivities of >95% after 21 days after symptom onset. Notably, cross-reactivity with other respiratory viruses (parainfluenza virus [PIV-4] [n = 5], human metapneumovirus [hMPV] [n = 3], rhinovirus/enterovirus [n = 1], CoV-229E [n = 2], CoV-NL63 [n = 2], and CoV-OC43 [n = 2]) was observed; however, overall specificity of EIAs was good (92 to 100%; all but one assay had specificity above 95%). POCTs were 0 to 100% sensitive >21 days after onset, with specificity ranging from 96 to 100%. However, many POCTs had faint banding and were often difficult to interpret. Serology assays can detect SARS-CoV-2 antibodies as early as 10 days after symptom onset. Serology assays vary in their sensitivity based on the marker (IgA/IgM versus IgG versus total) and by manufacturer; however, overall only 4 EIAs and 4 POCTs had sensitivities of >95% >21 days after symptom onset. Cross-reactivity with other seasonal coronaviruses is of concern. Serology assays should not be used for the diagnosis of acute infection but rather in carefully designed serosurveys to facilitate understanding of seroprevalence in a population and to identify previous exposure to SARS-CoV-2.

Examination of a Canadian provincial prenatal HIV screening program: 2010 to 2014

OBJECTIVES

Universal prenatal screening in the Canadian province of Alberta employs an 'opt-out' HIV screening strategy. We examined all women giving birth in the province and determined the frequency and characteristics of women having and not having HIV screening.

METHODS

All livebirths in Alberta from January 1, 2010 to December 31, 2014 were compiled from the Vital Statistics database and linked to HIV screening data to determine maternal demographic and prenatal care characteristics. Correlates associated with prenatal HIV screening, opting out of HIV screening, and not having any prenatal communicable disease screening were determined by multivariable statistics.

RESULTS

Of the 256,280 live births, 94.2% had prenatal HIV screening, 1.9% declined prenatal HIV screening, and 3.9% had no record of any prenatal communicable disease testing. Compared with those who had HIV screening, those who opted out of prenatal HIV screening were more likely to be over 40 years of age (adjusted odds ratio (AOR), 2.83 [2.12-3.78]) and less likely to be single (AOR, 0.67 [0.62-0.73]) and First Nations (AOR, 0.67 [0.56-0.82]). Those who received no prenatal communicable disease screening were less likely to be over 40 years of age (AOR, 0.81 [0.69-0.95]) and more likely to be single (AOR, 1.27 [1.21-1.33]) and have received no prenatal care (AOR, 6.78 [6.40-7.19]). Both the HIV decliners and prenatal non-testers were more likely to have used a midwife (AOR, 4.52 [3.83-5.35] and AOR, 2.44 [2.03-2.92], respectively).

CONCLUSION

Demographic and prenatal care characteristics differ by a pregnant woman's prenatal screening status. Policies to improve HIV screening coverage should take these variations into account.

Overview of a Provincial Prenatal Communicable Disease Screening Program: 2002-2016

OBJECTIVE

This study sought to provide a 14-year overview of serological results from a provincial prenatal screening program.

METHODS

Prenatal screening data from August 2002 to December 2016 were extracted from the Alberta Public Health Laboratory (ProvLab) Information system. Data were analyzed by year, communicable disease marker, test result, and maternal age category. The age-stratified proportion of seropositive results for hepatitis B virus, human immunodeficiency virus, and syphilis was determined, and the proportion of seronegative results was determined for rubella and varicella. The Mann Kendall Trend Test was performed to identify significant temporal trends in the results (Canadian Task Force Classification II-2).

RESULTS

In total 821 910 prenatal specimens were examined. Overall, the proportion of prenatal specimens positive for hepatitis B virus showed a slight statistically significant upward trend from 0.50% in 2003 to 0.58% in 2016 (P = 0.03). The proportion of positive human immunodeficiency virus prenatal specimens showed no significant trend over the study period. The proportion of positive syphilis specimens increased from 2006 to 2008 (0.07% to 0.21%; P < 0.0001) and stayed relatively constant until a decrease began in 2015. The proportion of seronegative specimens for varicella and rubella showed a significant upward trend of 0.48% per year (P < 0.01) and 0.88% per year (P < 0.01), respectively.

CONCLUSION

The Alberta Prenatal Screening Program for Selected Communicable Diseases presents a unique data set that allows us to look at screening results on a provincial level. Trends in results are reflective of communicable disease trends in the general population and should be monitored for effective infectious disease management of the maternal and newborn population.

Examination of a prenatal syphilis screening program, Alberta, Canada: 2010-2011

OBJECTIVES

In 2009, due to increasing congenital syphilis rates, prenatal syphilis tests (PST) at both mid-gestation and delivery were added to first trimester prenatal screening in the province of Alberta. We sought to determine the proportion of mothers who had all three recommended PSTs during this period and to identify factors associated with incomplete PST.

METHODS

A cohort of all pregnancies resulting in a live or stillborn infant in Alberta for 2010 and 2011 was developed from Vital Statistics and linked with prenatal screening data to determine the number and timing of PSTs for pregnant women. The proportion of women who had PSTs at the three recommended time points in pregnancy and associated correlates were identified using basic statistics and logistic regressions.

RESULTS

Of 99,609 pregnancies, 20.7% had all three PSTs at the recommended time points. Overall, 98.5% (98,162) had at least one PST, 1.5% only had PST at delivery and 1.5% had no PST performed. Independent risk factors for not having the three recommended PSTs included First Nations status (adjusted odds ratio [AOR]: 1.78 [95% CI: 1.62-1.96]), rural remote residence (AOR 3.61 [95% CI: 3.10-4.20]) and sole use of a midwife for prenatal care (AOR 13.70 [95% CI: 9.20-20.39]).

CONCLUSIONS

Nearly all pregnant women in Alberta received a PST at least once during their pregnancy, however far fewer received PSTs at the recommended time points. Interventions that target those who are less likely to be prenatally screened may help to ensure that pregnant women get early and appropriate care for syphilis during pregnancy.

Hepatitis B and C serologic profiles of Canadian organ donors and recipients: retrospective 10-year review at a single center

BACKGROUND

Hepatitis C virus (HBV) and hepatitis C virus (HCV) are important causes of hepatitis and can be transmitted from organ donor to recipient. This study aimed to determine HBV and HCV serologic profiles of a population of Canadian solid organ transplant (SOT) donors and recipients, including prevalence of recipient HBV immunity.

METHODS

Data on age, gender, organ transplanted, and pre-transplant HBV and HCV serology for SOT donors and recipients at a Canadian hospital from 2001 to 2011 were obtained from a transplant database.

RESULTS

There were 2455 recipients (2205 adults, 250 children), and 1559 donors. Over 50% of adult and 44% of pediatric recipients were HBV non-immune pre-transplant. Pediatric recipients were more likely to have HBV vaccine immunity than were adult recipients (48.8% vs. 28.9%, P < 0.001). Prevalence of HBV vaccine immunity was highest in renal recipients (48.3% in adult, 63.2% in pediatric recipients). Recipient HBV vaccine immunity increased from 5.8% in 2001 to 44.5% in 2011 (P < 0.001). Of 134 adult recipients with prior HBV infection, 59 (44%) were co-infected with HCV. Only 0.6% of adult non-liver recipients had acute or chronic HBV infection and 3.2% were anti-HCV positive. Only 2 donors had acute or chronic HBV infection, 29 had prior HBV infection, 9 were isolated hepatitis B core antibody positive, and 15 were anti-HCV positive.

CONCLUSIONS

The prevalence of HBV vaccine immunity in SOT candidates is low, but increased from 2001 to 2011. Opportunities for quality improvement in pre-transplant HBV immunization exist. HCV co-infection is common in recipients with prior HBV infection. Prevalence of HCV infection in non-liver transplant recipients is low.

Determining rubella immunity in pregnant Alberta women 2009-2012

Rubella IgG levels for 157,763 pregnant women residing in Alberta between 2009 and 2012 were analyzed. As there have been no reported cases of indigenous rubella infection in Canada since 2005, there has been a lack of naturally acquired immunity, and the current prenatal population depends almost entirely on vaccine induced immunity for protection. Rubella antibody levels are significantly lower in younger maternal cohorts with 16.8% of those born prior to universal vaccination programs (1971-1980), and 33.8% of those born after (1981-1990) having IgG levels that are not considered protective (<15 IU/mL). Analysis across pregnancies showed only 35.0% of women responded with a 4-fold increase in antibody levels following post-natal vaccination. Additionally, 41.2% of women with antibody levels <15 IU/mL had previously received 2 doses of rubella containing vaccine. These discordant interpretations generate a great deal of confusion for laboratorians and physicians alike, and result in significant patient follow-up by Public Health teams. To assess the current antibody levels in the prenatal population, latent class modeling was employed to generate a two class fit model representing women with an antibody response to rubella, and women without an antibody response. The declining level of vaccine-induced antibodies in our population is disconcerting, and a combined approach from the laboratory and Public Health may be required to provide appropriate follow up for women who are truly susceptible to rubella infection.

Factors associated with vaccine failure and vertical transmission of hepatitis B among a cohort of Canadian mothers and infants

Mother-to-child transmission of hepatitis B virus (HBV) continues to occur despite immunoprophylaxis. We examined maternal factors contributing to transmission in infants receiving adequate immunoprophylaxis in Alberta, Canada. Prenatal specimens from HBsAg-positive women whose babies developed HBV infection despite immunoprophylaxis (cases) and HBsAg-positive mothers whose babies did not (controls) were tested for HBsAg, HBeAg and HBV DNA. Specimens with detectable DNA underwent HBV genotyping. Routinely collected surveillance data and laboratory test results were compared between cases and controls. Twelve cases and 52 controls were selected from a provincial registry from 2000 to 2005. At the time of prenatal screening, median maternal age was 31 years [interquartile range (IQR): 27.5-34.5], and median gestational age was 12 weeks (IQR 10.0-15.5). Cases were more likely than controls to test positive for HBeAg (77.8% vs. 23.1%; P < 0.05). Of all mothers with detectable viral load (n = 51), cases had a significantly higher median viral load than did controls (5.6 × 10(8)  IU/mL vs. 1750 IU/mL, P < 0.0001). Of the two cases who were HBeAg negative, one had an undetectable viral load 8 months prior to delivery and a sP120T mutation. The viral load in the other case was 14,000 IU/mL. The majority of isolates were genotype B (31.3%) and C (31.3%) with no significant differences in genotype between cases or controls. In this case-control study, transmission of HBV to infants was more likely to occur in mothers positive for HBeAg and with high HBV DNA.

Time to testing and accessing care among a population of newly diagnosed patients with HIV with a high proportion of Canadian Aboriginals, 1998-2003

Early HIV diagnosis and treatment are important for decreasing HIV transmission and morbidity. By using initial CD4 counts and time to first viral load test, we examined the stage of disease at the time of diagnosis and the time to accessing medical care after diagnosis, respectively. Initial CD4 count, first HIV viral load test, demographics and exposure risks were obtained for all newly diagnosed HIV cases in Northern Alberta from 1998-2003. Time to accessing care was determined as the time between diagnosis and the first viral load test. Correlates were determined using simple descriptive statistics and survival analysis methods. Of 526 HIV cases, median age was 36 years (interquartile range [IQR]: 31-43), 69% were males and 41% were Aboriginal. At diagnosis, 28% of the population had CD4 counts less than 200 cells=mm3. After diagnosis, 92.2% accessed care and median time to care for the entire population was 29 days. In multivariate analysis, age at diagnosis less than 45 years was independently associated with longer median time to care (versus age 45 years or more; adjusted hazard ratio [AHR]: 0.69; 95% confidence interval [CI] 0.55-0.88), while Aboriginal ethnicity (versus Caucasian; AHR: 0.82; 95% CI 0.68-1.01), and nonmetropolitan residence (versus metropolitan; AHR: 0.81; 95% CI 0.65-1.00) were marginally significant correlates for longer times to care. Although more than one quarter of cases were diagnosed at relatively advanced stages of infection, the majority of new HIV cases in Northern Alberta accessed care within 2 months of diagnosis. We need to explore new strategies to facilitate and promote earlier access to testing among individuals at risk.

HIV seroprevalence among women opting out of prenatal HIV screening in Alberta, Canada: 2002-2004

Alberta, Canada, uses an "opt-out" strategy for prenatal HIV testing. We examined demographic characteristics of and HIV seroprevalence among women opting out. The proportion of total specimens that were from women who opted out decreased from 4.3% in 2002 to 3.6% in 2004 (P<.001), and HIV seroprevalence among these specimens was 0.07%, which was 3.3 times higher than the HIV seroprevalence among specimens from women who opted in. Women opting out may have a higher HIV infection risk.

Outcomes from a Canadian public health prenatal screening program for hepatitis B: 1997-2004

BACKGROUND

Without appropriate prophylaxis, the rate of vertical transmission of hepatitis B virus (HBV) can be as high as 95%. Alberta's provincial prenatal program screens all pregnant women for HBV, and provides prophylaxis to infants born to HBV-infected women. Canadian data on the outcomes of such programs are limited.

METHODS

We conducted a retrospective review of data from pregnant Albertan women who were Hepatitis B Surface Antigen (HBsAg) positive from 1997-2004. We describe the frequency of hepatitis B immunoglobulin (HBIG) and vaccine administration, follow-up serology and pregnancy outcomes.

RESULTS

In total, 1,485 HBsAg-positive pregnant women were identified; an average of 186 women annually (range: 125-216). Of the 980 infants eligible to have completed prophylaxis and serological follow-up, 82.0% were appropriately immunized and serologically tested, 11.3% had complete immunization but no serology testing and 6.6% were incompletely immunized. Of infants with complete immunization and follow-up, 3.7% failed to mount an immune response and 2.1% were infected.

CONCLUSION

A high proportion of infants born to carrier mothers are receiving appropriate post-natal prophylaxis in Alberta. Future research should examine maternal factors that may increase the vertical transmission of HBV.

Human papillomavirus seroprevalence among young male and female drug users

OBJECTIVES

To determine seroprevalence and correlates of exposure to HPV 16, 18, and 53 among 15- to 30-year-old drug users in Baltimore, MD.

STUDY DESIGN

Young, newly initiated injection and noninjection drug users underwent a behavioral risk assessment and HPV serology testing. Sex-specific analyses were performed comparing seropositive and seronegative participants using chi2, Mann-Whitney tests, and logistic regression.

RESULTS

Participants (n = 553) were 43.0% female, 40.2% African American, and median age was 24 years. HPV seroprevalence among females and males, respectively, was: HPV-16, 38.2% and 7.0%; HPV-18, 42.4% and 7.3%; and HPV-53, 27.7% and 5.1%. Correlates of HPV seropositivity among females included being African American and anal sex, and among males, having had sex with another male.

CONCLUSIONS

HPV seroprevalence was high among young drug users and significantly higher among females than males, supporting previous findings. Further research is required to fully understand HPV risk factors among men and the contribution of anal transmission in women.

Outcomes from a Canadian public health prenatal screening program for hepatitis B: 1997-2004

BACKGROUND

Without appropriate prophylaxis, the rate of vertical transmission of hepatitis B virus (HBV) can be as high as 95%. Alberta's provincial prenatal program screens all pregnant women for HBV, and provides prophylaxis to infants born to HBV-infected women. Canadian data on the outcomes of such programs are limited.

METHODS

We conducted a retrospective review of data from pregnant Albertan women who were Hepatitis B Surface Antigen (HBsAg) positive from 1997-2004. We describe the frequency of hepatitis B immunoglobulin (HBIG) and vaccine administration, follow-up serology and pregnancy outcomes.

RESULTS

In total, 1,485 HBsAg-positive pregnant women were identified; an average of 186 women annually (range: 125-216). Of the 980 infants eligible to have completed prophylaxis and serological follow-up, 82.0% were appropriately immunized and serologically tested, 11.3% had complete immunization but no serology testing and 6.6% were incompletely immunized. Of infants with complete immunization and follow-up, 3.7% failed to mount an immune response and 2.1% were infected.

CONCLUSION

A high proportion of infants born to carrier mothers are receiving appropriate post-natal prophylaxis in Alberta. Future research should examine maternal factors that may increase the vertical transmission of HBV.

Prevalence and estimated incidence of blood-borne viral pathogen infection in organ and tissue donors from northern Alberta

To determine the potential safety benefit of introducing nucleic acid testing (NAT) in tissue and organ donors, the risk of virus transmission was examined in a Canadian population. Anonymous data on Northern Alberta tissue and organ donors from 1998 to 2004 were used to determine the seroprevalence and estimate the seroincidence and residual risk of HIV, HBV, HCV and HTLV infection. Of the 3372 donors identified, 71.1% were surgical bone, 13.2% were living organ and 15.6% were deceased organ/tissue donors. Seroprevalence was: HIV 0.00%, HBV 0.09%, HCV 0.48% and HTLV 0.03%. Incidence (/100,000 p-yrs) and residual risks (/100,000 donors) could only be estimated for HBV (24.2 and 3.9) and HCV (11.2 and 2.2). Risk estimates were higher for deceased donors than surgical bone donors. HCV had the highest prevalence and HBV had the highest estimated incidence. HIV and HTLV risks were extremely low precluding accurate quantification. In this region of low overall viral prevalence, HCV NAT would be most effective in deceased organ donors. In surgical bone donors the cost of implementing NAT is high without significant added safety benefit.

Herpes simplex virus 2 and syphilis among young drug users in Baltimore, Maryland

OBJECTIVES

To examine the sex specific seroprevalence and correlates of herpes simplex virus 2 (HSV-2) and syphilis among a cohort of young drug users.

METHODS

Drug users aged 15-30 years old who used heroin, cocaine, or crack were recruited between October 1999 and August 2002. Baseline interviews gathered information on sociodemographics, drug use and sexual behaviours. Serum was tested at baseline for HSV-2 and syphilis seroreactivity. For each sexually transmitted infection (STI), infected and non-infected participants were stratified by sex and compared using chi2, Mann-Whitney tests, and logistic regression.

RESULTS

Of the 543 participants recruited, 42.4% were female and 39.3% were African-American. The seroprevalence of STIs among females and males, respectively, were HSV-2: 58.7% and 22.0%; syphilis: 4.3% and 0.3%. In multivariate models, older age, African-American race, having over 30 lifetime sex partners, current HIV infection and previous incarceration were independently associated with HSV-2 infection among males. For females, older age, African-American race, sex trade, and daily heroin use were independently associated with HSV-2. For females, only a self reported previous syphilis diagnosis was associated with current syphilis seroreactivity in multivariate analyses.

CONCLUSIONS

Examination of this cohort revealed a particularly high seroprevalence of HSV-2 and syphilis, especially among female drug users. Few infected participants had been previously diagnosed with these infections.

Prevalence and Correlates of Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis infections, and Bacterial Vaginosis Among a Cohort of Young Injection Drug Users in Baltimore, Maryland

OBJECTIVES

Injection drug users (IDUs) consistently demonstrate high-risk behaviors for sexually transmitted infections (STIs). This study examines STI prevalence and correlates among young IDUs.

STUDY

This cross-sectional study recruited IDUs aged 18 to 30 years. Participants completed a behavioral risk assessment and were tested for chlamydia, gonorrhea, and trichomoniasis by nucleic acid amplification methods. Women were also tested for bacterial vaginosis (BV). Gender-specific analyses were done comparing infected with noninfected participants using chi-square, Mann-Whitney tests, and logistic regression.

RESULTS

Of the 115 (35.3%) women and 211 (64.7%) men in the study, STI prevalence, respectively, was: chlamydia, 5.3% and 3.3%; gonorrhea, 3.5% and 0%; and trichomoniasis, 8.6% and 1.9%. Most (68.0%) participants had 2 or more sex partners in the past 3 months, of whom fewer than half consistently used condoms. Independent correlates for prevalent STIs included douching (adjusted odds ratio [AOR], 4.9; 95% confidence interval [CI], 1.5-23.6) for women and anal sex with female partners (AOR, 6.3; 95% CI, 1.5-25.8) for men. BV prevalence was 56.3% and was associated with douching (OR, 2.5; 95% CI, 1.1-5.7).

CONCLUSIONS

Despite high sexual risk, STI prevalence among young IDUs was similar to that of the general population. BV prevalence was high, suggesting that future STI assessments among female IDUs should include BV.

Prevalence and determinants of tuberculin reactivity among physicians in Edmonton, Canada: 1996-1997

BACKGROUND

Health care workers (HCW) have historically borne a heavy burden of tuberculosis (TB) infection and disease. Unfortunately, physicians are rarely included in HCW surveys of tuberculin exposure and infection.

METHODS

The prevalence and risk factors for tuberculin reactivity were determined for a sample of the 1732 licensed physicians in Edmonton. Stratified random sampling was used to select 554 specialists and 219 general practitioners. These physicians were contacted by means of an introductory letter and a follow-up telephone call to solicit participation. All eligible physicians were asked to complete a questionnaire and those with either no recorded positive tuberculin test or a previously negative result were two-step tuberculin skin tested.

RESULTS

In total, 560 physicians (72.4 %) participated in the study. The overall tuberculin reactivity for this population was 45.9%. Using logistic regression analysis, we determined that risk factors for reactivity were aged over 45 years, of foreign-birth, previous Bacillus Calmette-Guérin (BCG) vaccination, foreign practice experience, and being a respiratory medicine specialist.

CONCLUSION

The prevalence of tuberculin reactivity among physicians is considerably higher than estimates for the general Canadian population. This observed excess risk may be associated with factors linked to their medical practice. The high participation rate suggests physician willingness to participate in this type of research, and emphasizes the need to include them in routine HCW surveillance.