Summary of available surveillance data on hepatitis C virus infection from eight Arctic countries, 2012 to 2014.

We summarised available hepatitis C virus (HCV) surveillance data for 2012-14 from Arctic/sub-Arctic countries/regions. We sent a HCV data collection template by email to public health authorities in all jurisdictions. Population statistics obtained from census sources for each country were used to estimate rates of reported acute and chronic/undifferentiated HCV cases. Seven countries with Arctic regions (Canada, Denmark, Finland, Greenland, Norway, Sweden and the United States, represented by the state of Alaska), including three Canadian territories and one province, as well as 11 Russian subnational Arctic regions, completed the data collection template. Data on acute HCV infection during 2014 was available from three Arctic countries and all Russian Arctic regions (rate range 0/100,000 population in Greenland, as well as Nenets and Chukotka Automous Okrugs (Russian subnational Arctic regions) to 3.7/100,000 in the Russian Republic of Komi). The rate of people with chronic/undifferentiated HCV infection in 2014 ranged from 0/100,000 in Greenland to 171.2/100,000 in Alaska. In most countries/regions, the majority of HCV-infected people were male and aged 19-64 years. Differences in surveillance methods preclude direct comparisons of HCV surveillance data between Arctic countries/regions. Our data can inform future efforts to develop standardised approaches to HCV surveillance in the Arctic countries/regions by identifying similarities/differences between the surveillance data collected.

Genomic Epidemiology and Molecular Resistance Mechanisms of Azithromycin-Resistant Neisseria gonorrhoeae in Canada from 1997 to 2014.

The emergence of Neisseria gonorrhoeae strains with decreased susceptibility to cephalosporins and azithromycin (AZM) resistance (AZM(r)) represents a public health threat of untreatable gonorrhea infections. Genomic epidemiology through whole-genome sequencing was used to describe the emergence, dissemination, and spread of AZM(r) strains. The genomes of 213 AZM(r) and 23 AZM-susceptible N. gonorrhoeae isolates collected in Canada from 1989 to 2014 were sequenced. Core single nucleotide polymorphism (SNP) phylogenomic analysis resolved 246 isolates into 13 lineages. High-level AZM(r) (MICs ≥ 256 µg/ml) was found in 5 phylogenetically diverse isolates, all of which possessed the A2059G mutation (Escherichia coli numbering) in all four 23S rRNA alleles. One isolate with high-level AZM(r) collected in 2009 concurrently had decreased susceptibility to ceftriaxone (MIC = 0.125 µg/ml). An increase in the number of 23S rRNA alleles with the C2611T mutations (E. coli numbering) conferred low to moderate levels of AZM(r) (MICs = 2 to 4 and 8 to 32 µg/ml, respectively). Low-level AZM(r) was also associated with mtrR promoter mutations, including the -35A deletion and the presence of Neisseria meningitidis-like sequences. Geographic and temporal phylogenetic clustering indicates that emergent AZM(r) strains arise independently and can then rapidly expand clonally in a region through local sexual networks.

Risk of transmission of HIV to infants during breast/chest feeding when mothers/birthing parents living with HIV are on antiretroviral therapy: a protocol for a rapid review.

INTRODUCTION: HIV is a major public health issue affecting millions globally. Women and girls account for 46% of new HIV infections in 2022 and approximately 1.3 million females become pregnant every year. Vertical transmission of HIV from persons living with HIV (PLHIV) to infants may occur through different modalities, such as through breast/chest feeding. Notably, 82% of PLHIV who chose to breast/chest feed are on antiretroviral therapy (ART) when feeding their infants. Precise estimates of the risk of postpartum transmission to infants during breast/chest feeding at varying viral load levels remain a significant gap in the literature. METHODS AND ANALYSIS: A rapid systematic search of electronic databases will be conducted from January 2005 to the present, including Medline, Embase and Global Health. The objective of this rapid review is to explore and assess the available evidence on the effect of varying viral load levels on the risk of HIV transmission to infants during breast/chest feeding when the birthing or gestational parent living with HIV is on ART. Study characteristics will be summarised and reported to support the narrative summary of the findings. The focus will be on the absolute risk of HIV transmission from birthing parent to infant during chest/breast feeding. The findings will also be stratified by month, including the risk of HIV transmission for 6 months and greater than 6 months postpartum. We will ascertain the risk of bias using A Measurement Tool to Assess Systematic Reviews 2, Quality of Prognosis Studies and Downs and Black checklist for the appropriate study type. A summary score will not be calculated, rather the strengths and limitations of the studies will be narratively described. ETHICS AND DISSEMINATION: No human subjects will be involved in the research. The findings of this rapid review will inform a future systematic review and will be disseminated through peer-reviewed publications, presentations and conferences. PROSPERO REGISTRATION NUMBER: CRD42024499393.

Second generation HIV surveillance in Pakistan: policy challenges and opportunities.

From 2004 to 2011, the Canada-Pakistan HIV/AIDS Surveillance Project (HASP) worked with government and non-government partners in Pakistan to design and implement an HIV second generation surveillance (SGS) system. Insights into the development of scalable cost effective surveillance methodologies, implementation, use of data for HIV prevention and human rights were gained over the course of HASP. An ideal SGS system would be affordable, able to be implemented independently by local partners and produce data that could be readily applied in policy and programmes. Flexibility in design and implementation is important to ensure that any SGS system is responsive to information needs, political changes and changes in key population dynamics and HIV epidemics. HASP's mapping methodology is innovative and widely accepted as best practice, but sustainability of the SGS system it developed is a challenge.

Translating knowledge from Pakistan's second generation surveillance system to other global contexts.

BACKGROUND: From 2004 to 2011, a collaborative project was undertaken to enhance the capacity of the Government of Pakistan to implement an effective second-generation surveillance system for HIV/AIDS, known as the HIV/AIDS Surveillance Project (HASP). In four separate rounds, behavioural questionnaires were administered among injection drug users, and female, male and hijra (transgender) sex workers. Dried blood spots were collected for HIV testing. METHODS: Through interviews with project staff in Pakistan and Canada, we have undertaken a critical review of the role of HASP in generating, using and translating knowledge, with an emphasis on capacity building within both the donor and recipient countries. We also documented ongoing and future opportunities for the translation of knowledge produced through HASP. RESULTS: Knowledge translation activities have included educational workshops and consultations held in places as diverse as Colombia and Cairo, and the implementation of HASP methodologies in Asia, the Middle East and sub-Saharan Africa. HASP methodologies have been incorporated in multiple WHO reports. Importantly, the donor country, Canada, has benefited in significant ways from this partnership. Operational and logistical lessons from HASP have, in turn, improved how surveillance is performed in Canada. Through this project, significant capacity was built among the staff of HASP, non-governmental organisations which were engaged as implementation partners, data coordination units which were established in each province, and in the laboratory. As is to be expected, different organisations have different agendas and priorities, requiring negotiation, at times, to ensure the success of collaborative activities. Overall, there has been considerable interest in and opportunities made for learning about the methodologies and approaches employed by HASP. CONCLUSIONS: Generally, the recognition of the strengths of the approaches and methodologies used by HASP has ensured an appetite for opportunities of mutual learning.

Geographical and temporal variation of injection drug users in Pakistan.

OBJECTIVES: We describe the characteristics of injecting drug users (IDU) in Pakistan in 2006 and 2011, and assess the heterogeneity of IDU characteristics across different cities and years as well as factors associated with HIV infection. METHODS: Cross-sectional, integrated behavioural-biological surveys of IDU were conducted in 10 cities across Pakistan in 2006 and 2011. Univariate and multivariable analyses were used to describe the differences in HIV prevalence and risk behaviours between cities and over time. RESULTS: Large increases in HIV prevalence among injection drug users in Pakistan were observed, with overall HIV prevalence increasing from 16.2% in 2006 to 31.0% in 2011; an increase in HIV prevalence was also seen in all geographic areas except one. There was an increase in risk behaviours between 2006 and 2011, anecdotally related to a reduction in the availability of services for IDU. In 2011, larger proportions of IDU reported injecting several times a day and using professional injectors, and fewer reported always using clean syringes. An increase in the proportion living on the street was also observed and this was associated with HIV infection. Cities differ in terms of HIV prevalence, risk profiles, and healthcare seeking behaviours. CONCLUSIONS: There is a high prevalence of HIV among injection drug users in Pakistan and considerable potential for further transmission through risk behaviours. HIV prevention programs may be improved through geographic targeting of services within a city and for involving groups that interact with IDU (such as pharmacy staff and professional injectors) in harm reduction initiatives.

Risk factors of HIV and variation in access to clean needles among people who inject drugs in Pakistan.

We identified key risk factors for HIV among people who inject drugs (PWID) in Pakistan and explored access to free clean needles. Multivariable logistic regression was used to investigate associations between HIV prevalence and demographic, behavioral, and socio-economic characteristics of PWID. Data came from the Government of Pakistan's Integrated Biological and Behavioral Surveillance (IBBS) Round 5 (2016-17; 14 cities). A secondary analysis investigated associations with reported access to clean needles. Unweighted HIV prevalence among 4,062 PWID (99% male) was 21.0%. Longer injecting duration (Odds ratio [OR] 1.06 [95% confidence interval: 1.02-1.10]; per year), higher injecting frequency (OR 1.67 [1.30-2.13]; per unit increase), and injecting heroin (OR 1.90 [1.11-3.25]) were positively associated with HIV prevalence. There was no association between using a used syringe at last injection and HIV. Having>10 years of education had lower odds of HIV than being illiterate (OR 0.58 [0.35-0.95]). Having a regular sexual partner (OR 0.74 [0.57-0.97]) or paying for sex with the opposite sex (OR = 0.62 [0.45-0.85]) had lower odds of HIV than not. Conversely, PWID paying a man/hijra for sex had higher odds of HIV (OR 1.20 [1.00-1.43]). Receipt of clean needles varied by city of residence (0-97% coverage), whilst PWID with knowledge of HIV service delivery programs had higher odds of receiving clean needles (OR 4.58 [3.50-5.99]). Injecting behaviors were associated with HIV prevalence among PWID, though risks related to paying for sex remain complicated. Geographical variation in access to clean needles suggests potential benefits of more widely spread public health services.

Key MessagesWhat is already known on this topicThe HIV epidemic in Pakistan is concentrated among key populations including people who inject drugs.What this study addsInjecting practices, sexual behaviors, and socio-economic factors are associated with HIV prevalence among people who inject drugs. Access to harm reduction services is varied in Pakistan.How this study might affect research, practice, or policyAccess to clean free needles, as well as service delivery programs, with a broad geographical reach remain important to curb the HIV epidemic among people who inject drugs in Pakistan.

Risk of sexual transmission of HIV in the context of viral load suppression.

Background: In 2018, the Public Health Agency of Canada (PHAC) published a systematic review to calculate the risk of sexual transmission of human immunodeficiency virus (HIV) in the context of antiretroviral therapy (ART). In 2022, PHAC commissioned the Canadian Agency for Drugs and Technologies in Health (CADTH) to conduct a rapid review of evidence published since 2017. We undertook a meta-analysis of relevant studies from these two reviews. Methods: Studies from the rapid review that adequately assessed exposure (HIV viral load) and outcome (HIV seroconversion) were included and assessed for risk of bias (RoB) and certainty of evidence. Results were pooled to estimate the risk of HIV transmission per 100 person-years. Results: Three studies from the rapid review were eligible for inclusion and one was excluded after RoB assessment. In the remaining studies examining risk among people living with HIV who take ART and maintain a suppressed viral load (fewer than 200 copies/mL, measured every 4-6 months), no sexual transmissions of HIV were observed. The pooled incidence estimate based on these studies, and one from the 2018 PHAC review, was zero transmissions/100 person-years (95% CI: 0.00-0.10). No studies in the rapid review provided data on the risk of sexual transmission of HIV in situations of varying levels of viral load. Conclusion: This update highlights the consistency of evidence since the 2018 PHAC review. There remains no evidence of HIV transmission to sexual partners when a person living with HIV is on ART and maintains a suppressed viral load.

The descriptive epidemiology of male sex workers in Pakistan: a biological and behavioural examination.

OBJECTIVES: There is a dearth of published information on the characteristics of sex workers in Pakistan. This study sought to characterise and compare hijra and non-hijra sex workers from eight large cities in Pakistan. DESIGN: χ(2) and Kruskal-Wallis tests, and multivariable logistic regression were used where appropriate. METHODS: Study respondents were described on demographic, sex-work, and risk behaviour variables using a cross-sectional integrated biological and behavioural quantitative survey. RESULTS: A total of 3350 respondents were surveyed, of which 2694 were included in the study. The average age of respondents was 24.1 years (SD 6.3), and the average duration of sex work was 7.5 years (SD 5.9). Respondents averaged 30.9 (SD 2.7) paid receptive anal sex acts in the month prior to their interview, while 21.5% reported using a condom during their last occurrence of paid anal sex. Of those surveyed, HIV prevalence was 5.4 per 1000; notably, no HIV-positive respondents reported any injection drug use. Finally, intercity heterogeneity was observed on demographic, sex work and risk behaviour characteristics, with almost all characteristics differing at the p < 0.01 level. CONCLUSIONS: Low levels of education, high volume of sex acts and suboptimal condom use makes for a potentially volatile situation. Information provided by this study can play an important role in designing effective prevention programmes, particularly in capturing heterogeneity in sex work between cities, and as evidence is accumulating that a shift in epidemic phase, as well as affected populations is occurring in Pakistan.

Trends in HIV pre-exposure prophylaxis use in eight Canadian provinces, 2014-2018.

INTRODUCTION: : Canada has endorsed the Joint United National Programme on HIV and AIDS global targets to end the acquired immunodeficiency syndrome (AIDS) epidemic, including reducing new human immunodeficiency virus (HIV) infections to zero, by 2030. Given the effectiveness of pre-exposure prophylaxis (PrEP) to prevent new infections, it is important to measure and report on PrEP utilization to help inform planning for HIV prevention programs and policies. METHODS: : Annual estimates of persons using PrEP in Canada were generated for 2014-2018 from IQVIA's geographical prescription monitor dataset. An algorithm was used to distinguish users of tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) for PrEP versus treatment or post-exposure prophylaxis. We provide the estimated number of people using PrEP in eight Canadian provinces by sex, age group, prescriber specialty and payment type. RESULTS: : The estimated number of PrEP users increased dramatically over the five-year study period, showing a 21-fold increase from 460 in 2014 to 9,657 in 2018. Estimated PrEP prevalence was 416 users per million persons across the eight provinces in 2018. Almost all PrEP users were male. Use increased in both sexes, but increase was greater for males (23-fold) than females (five-fold). Use increased across all provinces, although there were jurisdictional differences in the prevalence of use, age distribution and prescriber types. CONCLUSION: : The PrEP use in Canada increased from 2014 to 2018, demonstrating increased awareness and uptake of its use for preventing HIV transmission. However, there was uneven uptake by age, sex and geography. Since new HIV infections continue to occur in Canada, it will be important to further refine the use of PrEP, as populations at higher risk of HIV infection need to be offered PrEP as part of comprehensive sexual healthcare.

Hepatitis B virus elimination status and strategies in circumpolar countries, 2020.

Hepatitis B virus (HBV) infection remains a global health threat. The World Health Organization (WHO) established a goal to eliminate HBV infection as a public health threat by 2030, and defined targets for key interventions to achieve that goal. We evaluated HBV burden and relevant national recommendations for progress towards WHO targets in circumpolar countries. Viral hepatitis experts of circumpolar countries were surveyed regarding their country's burden of HBV, achievement of WHO targets and national public health authority recommendations for HBV prevention and control. Eight of nine circumpolar countries responded. All countries continue to see new HBV infections. Data about HBV prevalence and progress in reaching WHO 2030 elimination targets are lacking. No country was able to report data for all seven WHO target measures. All countries have recommendations targeting the prevention of mother-to-child transmission. Only the USA and Greenland recommend universal birth dose vaccination. Four countries have recommendations to screen persons at high risk for HBV. Existing recommendations largely address prevention; however, recommendations for universal birth dose vaccination have not been widely introduced. Opportunities remain for the development of trackable targets and national elimination planning to screen and treat for HBV to reduce incidence and mortality.

Elucidating Drivers for Variations in the Explosive Human Immunodeficiency Virus Epidemic Among People Who Inject Drugs in Pakistan.

BACKGROUND: Pakistan's explosive human immunodeficiency virus (HIV) epidemic among people who inject drugs (PWID) varies widely across cities. We evaluated possible drivers for these variations. METHODS: Multivariable regression analyses were undertaken using data from 5 national surveys among PWID (n = 18 467; 2005-2017) to determine risk factors associated with variations in city-level HIV prevalence. A dynamic HIV model was used to estimate the population-attributable fraction (PAF; proportion of HIV infections prevented over 10 years when that risk factor is removed) of these risk factors to HIV transmission and impact on HIV incidence of reducing their prevalence. RESULTS: Regression analyses suggested that city-level HIV prevalence is strongly associated with the prevalence of using professional injectors at last injection, heroin use in last month, and injecting ≥4 times per day. Through calibrating a model to these associations, we estimate that the 10-year PAFs of using professional injectors, heroin use, and frequent injecting are 45.3% (95% uncertainty interval [UI], 4.3%-79.7%), 45.9% (95% UI, 8.1%-78.4%), and 22.2% (95% UI, 2.0%-58.4%), respectively. Reducing to lowest city-level prevalences of using professional injectors (2.8%; median 89.9% reduction), heroin use (0.9%; median 91.2% reduction), and frequent injecting (0.1%; median 91.8% reduction) in 2020 reduces overall HIV incidence by 52.7% (95% UI, 6.1%-82.0%), 53.0% (95% UI, 11.3%-80.2%), and 28.1% (95% UI, 2.7%-66.6%), respectively, over 10 years. CONCLUSIONS: Interventions should focus on these risk factors to control Pakistan's explosive HIV epidemic among PWID, including a concomitant expansion of high-coverage needle/syringe provision, opioid substitution therapy, and antiretroviral therapy.

Estimates of the number of prevalent and incident human immunodeficiency virus (HIV) infections in Canada, 2008.

OBJECTIVE: To estimate the number of prevalent and incident HIV infections in Canada in 2008. METHODS: We applied multiple methods to estimate national HIV prevalence and incidence in Canada, including the workbook method, two statistical modelling methods, and an iterative spreadsheet model. RESULTS: The estimated number of people living with diagnosed or undiagnosed HIV infection (including AIDS) continues to rise, from an estimated 57,000 in 2005 to 65,000 in 2008. Nearly half (48%) of these HIV-infected persons were men who have sex with men (MSM) and 22% were women. An estimated 16,900 persons with prevalent infection (26% of total prevalent infections) were unaware of their HIV-infected status and this proportion varied from an estimated 19% of HIV-infected MSM, to 25% of HIV-infected people who inject drugs, and 35% of HIV-infected heterosexuals. An estimated 3,300 new infections occurred in Canada in 2008, which was about the same as the estimate of 3200 in 2005. Of those new infections, 26% were among women and 12.5% were of Aboriginal descent; in terms of exposure category, MSM continued to comprise the greatest proportion of new infections (44%) and heterosexuals who originated in countries where HIV is endemic comprised 16%. CONCLUSION: HIV incidence in Canada is not decreasing. Aboriginal people and people from HIV-endemic countries continue to be over-represented in Canada's HIV epidemic. People unaware of their HIV infection are a priority for being tested and diagnosed to enable them to take advantage of care services and receive counselling to prevent further spread of HIV.

Seroprevalence and correlates of HIV and HCV among injecting drug users in Edmonton, Alberta.

BACKGROUND: Injection drug users (IDUs) are at risk for acquiring human immunodefiency virus (HIV) and hepatitis C virus (HCV) via parenteral and sexual transmission. We determined the seroprevalence and correlates of HIV and HCV for IDUs recruited in Edmonton, Alberta. METHODS: Edmonton was one site of a multi-site, national survey (I-Track Study). From April to June 2005, IDUs were recruited and administered a questionnaire collecting information on demographics, drug use, sexual behaviours, and HIV/HCV testing behaviours. Finger-prick blood samples were collected for serology testing. Seroprevalence of HIV and HCV was determined and correlates of infection were assessed using logistic regression. RESULTS: Of 275 IDUs, 68% were male, the median age was 38 years and 70.6% were Aboriginal. HIV prevalence was 23.9%, HCV prevalence was 66.1% and HIV/HCV co-infection was 22.8%. Cocaine (36.9%) was reported to be the drug injected most often in the previous six months. Correlates for HIV were sex trade (OR 2.9, 95% CI 1.0-8.3) for women, and older age (OR 1.1, 95% CI 1.0-1.2) and needle exchange program (NEP) use (OR 5.7, 95% CI 1.3-23.7) for men. For women, having a casual sex partner was protective for HCV (OR 0.28, 95% CI 0.10-0.78). Independent correlates for HCV among males included age (AOR 1.2, 95% CI 1.1-1.3) and younger age of first injection (AOR 0.92, 95% CI 0.87-0.96). CONCLUSION: The high HIV and HCV prevalence found in this study among IDUs in Edmonton highlights the complex needs of the IDU community and the continued need for targeted programming.

Laboratory-confirmed COVID-19 in children and youth in Canada, January 15-April 27, 2020.

Understanding the epidemiology of COVID-19 among children and youth in Canada will help to inform public health measures in settings where children gather. As of April 27, 2020, provinces and territories provided the Public Health Agency of Canada with detailed information on 24,079 cases, of which 3.9% (n=938) were younger than 20 years of age. The detection rate per 100,000 population was lower in this age group (11.9 per 100,000), compared with those aged 20-59 years (72.4 per 100,000) and 60 and older (113.6 per 100,000). The median age among those younger than 20 years of age was 13 years, and cases were distributed equally across male and female genders. Among provinces and territories with more than 100 cases, 1.6% to 9.8% of cases were younger than 20 years of age. Cases in this age group were more likely to be asymptomatic: 10.7% compared with 2.4% in those aged 20-59 years and 4.1% in those aged 60 and older. Children and youth experienced severe outcomes less often, but 2.2% (n=15/672) of cases within this age group were severe enough to require hospitalization. Based on available exposure information, 11.3% (n=59/520) of cases aged younger than 20 years had no known contact with a case. Canadian findings align with those of other countries.

HIV-1 phylodynamic analysis among people who inject drugs in Pakistan correlates with trends in illicit opioid trade.

Pakistan is considered by the World Health Organization to currently have a "concentrated" HIV-1 epidemic due to a rapid rise in infections among people who inject drugs (PWID). Prevalence among the country's nearly 105,000 PWID is estimated to be 37.8% but has been shown to be higher in several large urban centers. A lack of public health resources, the common use of professional injectors and unsafe injection practices are believed to have fueled the outbreak. Here we evaluate the molecular characteristics of HIV-1 sequences (n = 290) from PWID in several Pakistani cities to examine transmission dynamics and the association between rates of HIV-1 transmission with regards to regional trends in opioid trafficking. Tip-to-tip (patristic) distance based phylogenetic cluster inferences and BEAST2 Bayesian phylodynamic analyses of time-stamped data were performed on HIV-1 pol sequences generated from dried blood spots collected from 1,453 PWID as part of a cross-sectional survey conducted in Pakistan during 2014/2015. Overall, subtype A1 strains were dominant (75.2%) followed by CRF02_AG (14.1%), recombinants/unassigned (7.2%), CRF35_AD (2.1%), G (1.0%) and C (0.3%). Nearly three quarters of the PWID HIV-1 sequences belonged to one of five distinct phylogenetic clusters. Just below half (44.4%) of individuals in the largest cluster (n = 118) did seek help injecting from professional injectors which was previously identified as a strong correlate of HIV-1 infection. Spikes in estimated HIV-1 effective population sizes coincided with increases in opium poppy cultivation in Afghanistan, Pakistan's western neighbor. Structured coalescent analysis was undertaken in order to investigate the spatial relationship of HIV-1 transmission among the various cities under study. In general terms, our analysis placed the city of Larkana at the center of the PWID HIV-1 epidemic in Pakistan which is consistent with previous epidemiological data.

HIV testing and care in Canadian Aboriginal youth: a community based mixed methods study.

BACKGROUND: HIV infection is a serious concern in the Canadian Aboriginal population, particularly among youth; however, there is limited attention to this issue in research literature. The purpose of this national study was to explore HIV testing and care decisions of Canadian Aboriginal youth. METHODS: A community-based mixed-method design incorporating the Aboriginal research principles of Ownership, Control, Access and Possession (OCAP) was used. Data were collected through surveys (n = 413) and qualitative interviews (n = 28). Eleven community-based organizations including urban Aboriginal AIDS service organizations and health and friendship centres in seven provinces and one territory assisted with the recruitment of youth (15 to 30 years). RESULTS: Average age of survey participants was 21.5 years (median = 21.0 years) and qualitative interview participants was 24.4 years (median = 24.0). Fifty-one percent of the survey respondents (210 of 413 youth) and 25 of 28 interview participants had been tested for HIV. The most common reason to seek testing was having sex without a condom (43.6%) or pregnancy (35.4%) while common reasons for not testing were the perception of being low HIV risk (45.3%) or not having had sex with an infected person (34.5%). Among interviewees, a contributing reason for not testing was feeling invulnerable. Most surveyed youth tested in the community in which they lived (86.5%) and 34.1% visited a physician for the test. The majority of surveyed youth (60.0%) had tested once or twice in the previous 2 years, however, about one-quarter had tested more than twice. Among the 26 surveyed youth who reported that they were HIV-positive, 6 (23.1%) had AIDS at the time of diagnosis. Delays in care-seeking after diagnosis varied from a few months to seven years from time of test. CONCLUSION: It is encouraging that many youth who had tested for HIV did so based on a realistic self-assessment of HIV risk behaviours; however, for others, a feeling of invulnerability was a barrier to testing. For those who tested positive, there was often a delay in accessing health services.

Trends in human immunodeficiency virus diagnoses among men who have sex with men in North America, Western Europe, and Australia, 2000-2014.

PURPOSE: The aim of the article was to investigate recent trends in human immunodeficiency virus (HIV) diagnosis rates among men who have sex with men (MSM) in high-income countries in North America, Western Europe, and Australia. METHODS: Data on annual rates of HIV diagnoses among MSM aged 15 to 65 years from 2000 to 2014 were collected from 13 high-income countries. Joinpoint regression software was used to empirically determine country-specific trend periods. Trends in HIV diagnosis rates and in the proportion of diagnoses occurring in young MSM aged 15 to 24 years were analyzed using Poisson regression and log-binomial regression, respectively. RESULTS: Six countries experienced an increasing trend from 2000 to 2007-08 followed by either a stable or declining trend through 2014. Five countries had recently increasing trends, and two countries had one stable trend from 2000 to 2014. All 13 countries experienced increases in the proportion of diagnoses occurring in young MSM. CONCLUSIONS: Since 2008, half of the 13 high-income countries examined experienced stable or decreasing trends. Still, some countries continue to experience increasing HIV trends, and young MSM are increasingly represented among new diagnoses. Efforts to support early sexual health promotion, reduce barriers to pre-exposure prophylaxis, and improve care engagement for young MSM are critical to addressing current HIV trends.

Modelling the evolution of drug resistance in the presence of antiviral drugs.

BACKGROUND: The emergence of drug resistance in treated populations and the transmission of drug resistant strains to newly infected individuals are important public health concerns in the prevention and control of infectious diseases such as HIV and influenza. Mathematical modelling may help guide the design of treatment programs and also may help us better understand the potential benefits and limitations of prevention strategies. METHODS: To explore further the potential synergies between modelling of drug resistance in HIV and in pandemic influenza, the Public Health Agency of Canada and the Mathematics for Information Technology and Complex Systems brought together selected scientists and public health experts for a workshop in Ottawa in January 2007, to discuss the emergence and transmission of HIV antiviral drug resistance, to report on progress in the use of mathematical models to study the emergence and spread of drug resistant influenza viral strains, and to recommend future research priorities. RESULTS: General lectures and round-table discussions were organized around the issues on HIV drug resistance at the population level, HIV drug resistance in Western Canada, HIV drug resistance at the host level (with focus on optimal treatment strategies), and drug resistance for pandemic influenza planning. CONCLUSION: Some of the issues related to drug resistance in HIV and pandemic influenza can possibly be addressed using existing mathematical models, with a special focus on linking the existing models to the data obtained through the Canadian HIV Strain and DR Surveillance Program. Preliminary statistical analysis of these data carried out at PHAC, together with the general model framework developed by Dr. Blower and her collaborators, should provide further insights into the mechanisms behind the observed trends and thus could help with the prediction and analysis of future trends in the aforementioned items. Remarkable similarity between dynamic, compartmental models for the evolution of wild and drug resistance strains of both HIV and pandemic influenza may provide sufficient common ground to create synergies between modellers working in these two areas. One of the key contributions of mathematical modeling to the control of infectious diseases is the quantification and design of optimal strategies, combining techniques of operations research with dynamic modeling would enhance the contribution of mathematical modeling to the prevention and control of infectious diseases.