Estimating prevalence trends in adult gonorrhoea and syphilis in low- and middle-income countries with the Spectrum-STI model: results for Zimbabwe and Morocco from 1995 to 2016

Epidemiology of Trichomonas vaginalis infection in the Middle East and North Africa: systematic review, meta-analyses, and meta-regressions

BACKGROUND

Trichomoniasis, caused by the parasite Trichomonas vaginalis (TV), remains an underappreciated sexually transmitted infection (STI), primarily due to inadequate understanding of its epidemiology and public health implications. This study aimed to characterize TV epidemiology in the Middle East and North Africa (MENA).

METHODS

Systematic review and analysis of evidence sourced from international, regional, and national databases were conducted. Findings were reported following PRISMA guidelines. Random-effects meta-analyses and meta-regressions were performed to determine pooled mean prevalence, investigate associations with prevalence, and identify sources of between-study heterogeneity.

FINDINGS

The review identified 263 relevant publications, encompassing 462 TV prevalence measures. The pooled mean TV prevalence was estimated as follows: 4.7% (95% CI: 3.9-5.6%) in the general population of women, 17.2% (95% CI: 5.4-33.6%) among intermediate-risk populations, 10.3% (95% CI: 6.2-15.3%) among female sex workers, 13.9% (95% CI: 12.3-15.6%) among symptomatic women, 7.4% (95% CI: 1.9-15.5%) among infertility clinic attendees, 2.3% (95% CI: 0.1-6.3%) among women with miscarriages or ectopic pregnancies, and 1.6% (95% CI: 0.8-2.7%) among STI clinic attendees. Limited data were found for men. Multivariable meta-regressions explained >40% of the prevalence variation, unveiling a hierarchical prevalence pattern by population type, an inverse correlation with national income, and a prevalence decline at a rate of 1% per calendar year.

INTERPRETATION

Despite conservative sexual norms, MENA has a substantial TV prevalence, comparable to the global TV prevalence. The unexpectedly high prevalence of this curable infection may, in part, be attributed to limited access to and underutilization of STI screening and treatment services.

FUNDING

This work was supported by the Qatar Research, Development, and Innovation Council [ARG01-0522-230273] and by the Biomedical Research Program at Weill Cornell Medicine-Qatar.

Understanding dynamics and overlapping epidemiologies of HIV, HSV-2, chlamydia, gonorrhea, and syphilis in sexual networks of men who have sex with men

Introduction

We aimed to investigate the overlapping epidemiologies of human immunodeficiency virus (HIV), herpes simplex virus type 2 (HSV-2), chlamydia, gonorrhea, and syphilis in sexual networks of men who have sex with men (MSM), and to explore to what extent the epidemiology of one sexually transmitted infection (STI) relates to or differs from that of another STI.

Methods

An individual-based Monte Carlo simulation model was employed to simulate the concurrent transmission of STIs within diverse sexual networks of MSM. The model simulated sexual partnering, birth, death, and STI transmission within each specific sexual network. The model parameters were chosen based on the current knowledge and understanding of the natural history, transmission, and epidemiology of each considered STI. Associations were measured using the Spearman's rank correlation coefficient (SRCC) and maximal information coefficient (MIC).

Results

A total of 500 sexual networks were simulated by varying the mean and variance of the number of partners for both short-term and all partnerships, degree correlation, and clustering coefficient. HSV-2 had the highest current infection prevalence across the simulations, followed by HIV, chlamydia, syphilis, and gonorrhea. Threshold and saturation effects emerged in the relationship between STIs across the simulated networks, and all STIs demonstrated moderate to strong associations. The strongest current infection prevalence association was between HIV and gonorrhea, with an SRCC of 0.84 (95% CI: 0.80-0.87) and an MIC of 0.81 (95% CI: 0.74-0.88). The weakest association was between HSV-2 and syphilis, with an SRCC of 0.54 (95% CI: 0.48-0.59) and an MIC of 0.57 (95% CI, 0.49-0.65). Gonorrhea exhibited the strongest associations with the other STIs while syphilis had the weakest associations. Across the simulated networks, proportions of the population with zero, one, two, three, four, and five concurrent STI infections were 48.6, 37.7, 11.1, 2.4, 0.3, and < 0.1%, respectively. For lifetime exposure to these infections, these proportions were 13.6, 21.0, 22.9, 24.3, 13.4, and 4.8%, respectively.

Conclusion

STI epidemiologies demonstrate substantial overlap and associations, alongside nuanced differences that shape a unique pattern for each STI. Gonorrhea exhibits an "intermediate STI epidemiology," reflected by the highest average correlation coefficient with other STIs.

Epidemiology of gonorrhoea: systematic review, meta-analyses, and meta-regressions, World Health Organization European Region, 1949 to 2021

BackgroundEpidemiology of Neisseria gonorrhoeae (NG) infection remains inadequately understood.AimWe aimed to characterise NG epidemiology in Europe.MethodsWe used Cochrane and PRISMA guidelines to systematically review, report, synthesise and analyse NG prevalence data from 1949 to 30 September 2021. Random-effects meta-analyses estimated pooled prevalence. Meta-regression analyses investigated associations and sources of heterogeneity.ResultsThe 844 included publications yielded 1,573 prevalence measures. Pooled prevalence of current urogenital infection was 1.0% (95% CI: 0.7-1.2%) among general populations, 3.2% (95% CI: 1.8-4.8%) among female sex workers, 4.9% (95% CI: 4.2-5.6%) among sexually transmitted infection clinic attendees and 12.1% (95% CI: 8.8-15.8%) among symptomatic men. Among men who have sex with men, pooled prevalence was 0.9% (95% CI: 0.5-1.4%), 5.6% (95% CI: 3.6-8.1%), and 3.8% (95% CI: 2.5-5.4%), respectively, for current urogenital, anorectal or oropharyngeal infection. Current urogenital, anorectal or oropharyngeal infection was 1.45-fold (95% CI: 1.19-1.77%), 2.75-fold (95% CI: 1.89-4.02%) and 2.64-fold (95% CI: 1.77-3.93%) higher among men than women. Current urogenital infection declined 0.97-fold (95% CI: 0.96-0.98%) yearly, but anorectal and oropharyngeal infection increased (1.02-fold; 95% CI: 1.01-1.04% and 1.02-fold; 95% CI: 1.00-1.04%), respectively.ConclusionsNeisseria gonorrhoeae epidemiology in Europe has distinct and contrasting epidemiologies for vaginal sex transmission in heterosexual sex networks vs anal and oral sex transmission in MSM sexual networks. Increased transmission may facilitate drug-resistant strain emergence. Europe is far from achieving the World Health Organization target of 90% incidence reduction by 2030.

Gonorrhea prevalence in adults in Brazil: Spectrum-STI trend estimation, 2000-2020

BACKGROUND

Gonorrhea is not a notifiable disease in Brazil, and the national health information system does not collect data on reported cases or infection prevalence.

METHODS

We compiled published data on gonorrhea prevalence in Brazil from cross-sectional surveys and clinical trials between 2000 and 2020. The study entry criteria included a sample size of 50 or more, and Neisseria gonorrhoeae infection detected in urine, urethral, anal, or cervicovaginal specimens using either Nucleic Acid Amplification Test or culture. Gonorrhea prevalence trends between 2000 and 2020 were generated using Spectrum-STI, a statistical trend-fitting model.

RESULTS

Forty-five studies with 59 gonorrhea prevalence data points were identified. Fifty data points were for women and represented 21,815 individuals, eight for men encompassing a total of 4,587 individuals, and one for transgender people comprising 345 individuals. The Spectrum-STI estimate for the prevalence of urogenital infection with gonorrhea in women 15-49 in 2020 was 0.63% (95% confidence interval (CI): 0.13-2.23) and was lower than the 1.05% estimated value for 2000 (95% CI: 0.36-2.79). The corresponding figures for men were 0.70% (95% CI: 0.16-2.44) and 1.14% (95% CI: 0.34-3.15). Anal prevalence estimates could not be generated because of insufficient data (three data points).

CONCLUSIONS

These results suggest that the overall prevalence of genitourinary gonococcal infections in Brazil is less than 1%. Data on gonorrhea prevalence in men and in populations at increased STI vulnerability are limited.

Impact of an STI Diagnosis on People Living With HIV in La Romana, Dominican Republic: A Cross-Sectional, Qualitative, Descriptive Study

ABSTRACT

The objective of this study was to explore how receiving a sexually transmitted infection (STI) diagnosis affects subsequent STI knowledge and sexual risk behavior among key populations in La Romana, Dominican Republic (DR) who participated in a parent study 12 to 24 months before the current study. Nine participants, with a mean age of 37 years (range 20-54 years) and a female majority (89%), who were recruited from the parent study completed in-depth interviews, questionnaires assessing STI knowledge, and received STI testing. Interviews were analyzed using qualitative descriptive methodology and questionnaire data, comparing individual's responses between the parent and current studies. Participants reported safer sexual behaviors after original STI diagnosis, such as more frequent condom use. Questionnaires showed improvement in STI knowledge between the parent and current studies. Three participants had an STI reinfection. Findings warrant further exploration into more comprehensive and targeted STI treatment methods for key populations in the DR.

Reverse vaccinology approaches to introduce promising immunogenic and drug targets against antibiotic-resistant Neisseria gonorrhoeae: Thinking outside the box in current prevention and treatment

Gonorrhea is an urgent antimicrobial resistance threat and its therapeutic options are continuously getting restricted. Moreover, no vaccine has been approved against it so far. Hence, the present study aimed to introduce novel immunogenic and drug targets against antibiotic-resistant Neisseria gonorrhoeae strains. In the first step, the core proteins of 79 complete genomes of N. gonorrhoeae were retrieved. Next, the surface-exposed proteins were evaluated from different aspects such as antigenicity, allergenicity, conservancy, and B-cell and T-cell epitopes to introduce promising immunogenic candidates. Then, the interactions with human Toll-like receptors (TLR-1, 2, and 4), and immunoreactivity to elicit humoral and cellular immune responses were simulated. On the other hand, to identify novel broad-spectrum drug targets, the cytoplasmic and essential proteins were detected. Then, the N. gonorrhoeae metabolome-specific proteins were compared to the drug targets of the DrugBank, and novel drug targets were retrieved. Finally, the protein data bank (PDB) file availability and prevalence among the ESKAPE group and common sexually transmitted infection (STI) agents were assessed. Our analyses resulted in the recognition of ten novel and putative immunogenic targets including murein transglycosylase A, PBP1A, Opa, NlpD, Azurin, MtrE, RmpM, LptD, NspA, and TamA. Moreover, four potential and broad-spectrum drug targets were identified including UMP kinase, GlyQ, HU family DNA-binding protein, and IF-1. Some of the shortlisted immunogenic and drug targets have confirmed roles in adhesion, immune evasion, and antibiotic resistance that can induce bactericidal antibodies. Other immunogenic and drug targets might be associated with the virulence of N. gonorrhoeae as well. Thus, further experimental studies and site-directed mutations are recommended to investigate the role of potential vaccine and drug targets in the pathogenesis of N. gonorrhoeae.

Identifying youth at high risk for sexually transmitted infections in community-based settings using a risk prediction tool: a validation study

BACKGROUND : Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are the most common bacterial sexually transmitted infections (STIs) worldwide. In the absence of affordable point-of-care STI tests, WHO recommends STI testing based on risk factors. This study aimed to develop a prediction tool with a sensitivity of > 90% and efficiency (defined as the percentage of individuals that are eligible for diagnostic testing) of < 60%.

METHODS

This study offered CT/NG testing as part of a cluster-randomised trial of community-based delivery of sexual and reproductive health services to youth aged 16-24 years in Zimbabwe. All individuals accepting STI testing completed an STI risk factor questionnaire. The outcome was positivity for either CT or NG. Backwards-stepwise logistic regression was performed with p ≥ 0.05 as criteria for exclusion. Coefficients of variables included in the final multivariable model were multiplied by 10 to generate weights for a STI risk prediction tool. A maximum likelihood Receiver Operating Characteristics (ROC) model was fitted, with the continuous variable score divided into 15 categories of equal size. Sensitivity, efficiency and number needed to screen were calculated for different cut-points.

RESULTS

From 3 December 2019 to 5 February 2020, 1007 individuals opted for STI testing, of whom 1003 (99.6%) completed the questionnaire. CT/NG prevalence was 17.5% (95% CI 15.1, 19.8) (n = 175). CT/NG positivity was independently associated with being female, number of lifetime sexual partners, relationship status, HIV status, self-assessed STI risk and past or current pregnancy. The STI risk prediction score including those variables ranged from 2 to 46 with an area under the ROC curve of 0.72 (95% CI 0.68, 0.76). Two cut-points were chosen: (i) 23 for optimised sensitivity (75.9%) and specificity (59.3%) and (ii) 19 to maximise sensitivity (82.4%) while keeping efficiency at < 60% (59.4%).

CONCLUSIONS

The high prevalence of STIs among youth, even in those with no or one reported risk factor, may preclude the use of risk prediction tools for selective STI testing. At a cut-point of 19 one in six young people with STIs would be missed.

A Comparative Study of the Epidemiology of Treponemal Infection in the Volta and Oti Regions of Ghana: A Five-Year Multisite Parallel Population-Based Analysis vis-à-vis the Sentinel Survey

Treponemal infections can be blood-borne with great public health consequences. This study is aimed at comparatively describing the five-year (2013-2017) regional epidemiology of treponemal infection using pregnant women in the sentinel survey and apparently healthy blood donors as a proxy for the general population at four sentinel sites in the Volta and Oti Regions of Ghana. We analyzed retrospective data from 17,744 prospective blood donors aged 18 to 58 years and 7,817 pregnant women in a sentinel survey with ages from 15 to 49 years at Hohoe, Ho, Tongu, and Krachi West sentinel sites in the Volta and Oti Regions. Laboratory data extracted include variables such as age, gender, date of blood donation, and Treponema pallidum chromatographic immunoassay results from the blood banks of the four study sites. The five-year treponemal infection rate among the pregnant women in the sentinel survey and prospective blood donors was 0.79% and 2.38%, respectively. Site-specific infection rate for population-based/sentinel survey was 4.6%/1.1%, 2.0%/0.5%, 1.3%/1.1, and 1.2%/0.3% for Hohoe, Ho, Krachi West, and Tongu, respectively. Significant gender disparity in Treponemal infection rate exists with a male preponderance. The regional infection rate in the sentinel survey is lower compared to the general population. Therefore, the use of pregnant women as a proxy for population estimates could underestimate the burden in the study jurisdiction.

Factors associated with sexually transmitted infections among care-seeking adults in the African Cohort Study

OBJECTIVES

Sexually transmitted infections (STIs) are a major cause of morbidity. Understanding drivers of transmission can inform effective prevention programs. We describe STI prevalence and identify factors associated with STIs in four African countries.

METHODS

The African Cohort Study is an ongoing, prospective cohort in Kenya, Nigeria, Tanzania and Uganda. At enrollment, a physical exam was conducted and STI diagnosis made by a clinician using a syndromic management approach. Multivariable logistic regression was used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (95% CIs) for factors associated with an STI diagnosis.

RESULTS

As of June 2020, 3544 participants were enrolled. STI prevalence was 7.7% and did not differ by HIV status (p = 0.30). Prevalence differed by syndrome (3.5% vaginal discharge, 1.5% genital ulcer, 2.1% lower abdominal pain, 0.2% inguinal bubo). The odds of having an STI were higher at all sites compared to Kisumu West, Kenya, and among those with a primary level education or below compared to those with secondary or higher (aOR: 1.77; 95% CI: 1.32-2.38). The odds of an STI diagnosis was higher among participants 18-29 years (aOR: 2.29; 95% CI: 1.35-3.87), females (aOR: 2.64; 95% CI: 1.94-3.59), and those with depression (aOR: 1.78; 95% CI: 1.32-2.38). Among PLWH, similar factors were independently associated with an STI diagnosis. Viral suppression was protective against STIs (aOR: 2.05; 95% CI: 1.32-3.20).

CONCLUSIONS

Prevalence of STIs varied by site with young people and females most at risk for STIs. Mental health is a potential target area for intervention.

Serological Markers for Syphilis Among Persons Presenting With Syndromes Associated With Sexually Transmitted Infections: Results From the Zimbabwe STI Etiology Study

BACKGROUND

Syphilis prevalence in sub-Saharan Africa appears to be stable or declining but is still the highest globally. Ongoing sentinel surveillance in high-risk populations is necessary to inform management and detect changes in syphilis trends. We assessed serological syphilis markers among persons with sexually transmitted infections in Zimbabwe.

METHODS

We studied a predominantly urban, regionally diverse group of women and men presenting with genital ulcer disease (GUD), women with vaginal discharge and men with urethral discharge at clinics in Zimbabwe. Syphilis tests included rapid plasma reagin and the Treponema pallidum hemagglutination assay.

RESULTS

Among 436 evaluable study participants, 36 (8.3%) tested positive for both rapid plasma reagin and Treponema pallidum hemagglutination assay: women with GUD: 19.2%, men with GUD: 12.6%, women with vaginal discharge: 5.7% and men with urethral discharge: 1.5% (P < 0.0001).

CONCLUSIONS

Syphilis rates in Zimbabwe are high in sentinel populations, especially men and women with GUD.

Epidemiology of Chlamydia trachomatis in the Middle East and north Africa: a systematic review, meta-analysis, and meta-regression

BACKGROUND

The epidemiology of Chlamydia trachomatis in the Middle East and north Africa is poorly understood. We aimed to provide a comprehensive epidemiological assessment of C trachomatis infection in the Middle East and north Africa.

METHODS

We did a systematic review of C trachomatis infection as well as a meta-analysis and meta-regression of C trachomatis prevalence. We searched PubMed and Embase, as well as regional and national databases up to March 13, 2019, using broad search terms with no language or year restrictions. Any document or report including biological measures for C trachomatis prevalence or incidence was eligible for inclusion. We extracted all measures of current (genital or rectal), recent, and ever infection with C trachomatis. We estimated pooled average prevalence in different populations using random-effects meta-analysis. Factors associated with prevalence and sources of between-study heterogeneity were determined using meta-regression.

FINDINGS

We identified a total of 1531 citations, of which 255 reports contributed to 552 C trachomatis prevalence measures from 20 countries. No incidence measures were identified. Pooled prevalence of current genital infection was 3·0% (95% CI 2·3-3·8) in general populations, 2·8% (1·0-5·2) in intermediate-risk populations, 13·2% (7·2-20·7) in female sex workers, 11·3% (9·0-13·7) in infertility clinic attendees, 12·4% (7·9-17·7) in women with miscarriage, 12·4% (9·4-15·7) in symptomatic women, and 17·4% (12·5-22·8) in symptomatic men. Pooled prevalence of current rectal infection was 7·7% (4·2-12·0) in men who have sex with men. Substantial between-study heterogeneity was found. Multivariable meta-regression explained 29·0% of variation. Population type was most strongly associated with prevalence. Additional associations were found with assay type, sample size, country, and sex, but not with sampling methodology or response rate (about 90% of studies used convenience sampling and >75% had unclear response rate). There was no evidence for temporal variation in prevalence between 1982 and 2018.

INTERPRETATION

C trachomatis prevalence in the Middle East and north Africa is similar to other regions, but higher than expected given its sexually conservative norms. High prevalence in infertility clinic attendees and in women with miscarriage suggests a potential role for C trachomatis in poor reproductive health outcomes in this region.

FUNDING

National Priorities Research Program from the Qatar National Research Fund (a member of Qatar Foundation).

Prevalence of syphilis, gonorrhoea and chlamydia in women in Fiji, the Federated States of Micronesia, Papua New Guinea and Samoa, 1995-2017: Spectrum-STI model estimates

Objective

To estimate prevalence levels of and time trends for active syphilis, gonorrhoea and chlamydia in women aged 15-49 years in four countries in the Pacific (Fiji, the Federated States of Micronesia [FSM], Papua New Guinea [PNG] and Samoa) to inform surveillance and control strategies for sexually transmitted infections (STIs).

Methods

The Spectrum-STI model was fitted to data from prevalence surveys and screenings of adult female populations collected during 1995-2017 and adjusted for diagnostic test performance and to account for undersampled high-risk populations. For chlamydia and gonorrhoea, data were further adjusted for age and differences between urban and rural areas.

Results

Prevalence levels were estimated as a percentage (95% confidence interval). In 2017, active syphilis prevalence was estimated in Fiji at 3.89% (2.82 to 5.06), in FSM at 1.48% (0.93 to 2.16), in PNG at 3.91% (1.67 to 7.24) and in Samoa at 0.16% (0.07 to 0.37). For gonorrhoea, the prevalence in Fiji was 1.63% (0.50 to 3.87); in FSM it was 1.59% (0.49 to 3.58); in PNG it was 11.0% (7.25 to 16.1); and in Samoa it was 1.61% (1.17 to 2.19). The prevalence of chlamydia in Fiji was 24.1% (16.5 to 32.7); in FSM it was 23.9% (18.5 to 30.6); in PNG it was 14.8% (7.39 to 24.7); and in Samoa it was 30.6% (26.8 to 35.0). For each specific disease within each country, the 95% confidence intervals overlapped for 2000 and 2017, although in PNG the 2017 estimates for all three STIs were below the 2000 estimates. These patterns were robust in the sensitivity analyses.

Discussion

This study demonstrated a persistently high prevalence of three major bacterial STIs across four countries in WHO's Western Pacific Region during nearly two decades. Further strengthening of strategies to control and prevent STIs is warranted.

The Spectrum-STI Groups model: syphilis prevalence trends across high-risk and lower-risk populations in Yunnan, China

The Spectrum-STI model, structured by sub-groups within a population, was used in a workshop in Yunnan, China, to estimate provincial trends in active syphilis in 15 to 49-year-old adults. Syphilis prevalence data from female sex workers (FSW), men who have sex with men (MSM), and lower-risk women and men in Yunnan were identified through literature searches and local experts. Sources included antenatal care clinic screening, blood donor screening, HIV/STI bio-behavioural surveys, sentinel surveillance, and epidemiology studies. The 2017 provincial syphilis prevalence estimates were 0.26% (95% confidence interval 0.17-0.34%) in women and 0.28% (0.20-0.36%) in men. Estimated prevalence was 6.8-fold higher in FSW (1.69% (0.68-3.97%) than in lower-risk women (0.25% (0.18-0.35%)), and 22.7-fold higher in MSM (5.35% (2.74-12.47%) than in lower-risk men (0.24% (0.17-0.31%). For all populations, the 2017 estimates were below the 2005 estimates, but differences were not significant. In 2017 FSW and MSM together accounted for 9.3% of prevalent cases. These estimates suggest Yunnan's STI programs have kept the overall prevalence of syphilis low, but prevalence remains high in FSW and MSM. Strengthening efforts targeting FSW and MSM, and identification of other risk populations e.g. among heterosexual men, are critical to reduce syphilis.

Estimating the syphilis incidence and diagnosis rate in Japan: a mathematical modelling study

OBJECTIVES

The reported number of syphilis cases is increasing in Japan. In this study, we aimed to estimate both the incidence of infection and diagnosis-and-reporting rate using a mathematical model that captures the time course of infection.

METHODS

We analysed yearly notification data from 1961 to 2016 and stratified according to clinical stage and sex. We built a compartmental ordinary differential equations model to describe the natural epidemiological course of syphilis in which the incidence of infection and diagnosis-and-reporting rate were included as time-varying parameters that we estimated via the maximum likelihood method.

RESULTS

From 2008 to 2016, the estimated number of new syphilis cases among men and women was 1070 (95% CI 1037 to 1104) and 302 (95% CI 287 to 318), respectively, which was increased from the previous period (1999-2007) with 269 (95% CI 256 to 282) and 71 (95% CI 64 to 78) cases, respectively. The diagnosis-and-reporting rate did not vary greatly over time. We estimated the number of undiagnosed syphilis cases from either incubating or early clinical (ie, primary or secondary) infections in 2016 to be 262 (95% CI 249 to 275) and 79 (95% CI 74 to 84) for men and women, respectively.

CONCLUSIONS

The recent increase in reported cases of syphilis is owing to an increase in the number of infections. We found no evidence of time-dependent improvement in detection or reporting.

Second Order Segmented Polynomials for Syphilis and Gonorrhea Prevalence and Incidence Trends Estimation: Application to Spectrum's Guinea-Bissau and South Africa Data

This paper presents two approaches to smoothing time trends in prevalence and estimating the underlying incidence of remissible infections. In the first approach, we use second order segmented polynomials to smooth a curve in a bounded domain. In the second, incidence is modeled instead and the prevalence is reconstructed using the recovery rate which is assumed to be known. In both approaches, the number of knots and their positions are estimated, resulting in non-linear regressions. Akaike Information Criterion is used for model selection. The method is illustrated with Syphilis and Gonorrhea prevalence smoothing and incidence trend estimation in Guinea-Bissau and South Africa, respectively.

Global burden of maternal and congenital syphilis and associated adverse birth outcomes-Estimates for 2016 and progress since 2012

BACKGROUND

In 2007 the World Health Organization (WHO) launched the global initiative to eliminate mother-to-child transmission of syphilis (congenital syphilis, or CS). To assess progress towards the goal of <50 CS cases per 100,000 live births, we generated regional and global estimates of maternal and congenital syphilis for 2016 and updated the 2012 estimates.

METHODS

Maternal syphilis estimates were generated using the Spectrum-STI model, fitted to sentinel surveys and routine testing of pregnant women during antenatal care (ANC) and other representative population data. Global and regional estimates of CS used the same approach as previous WHO estimates.

RESULTS

The estimated global maternal syphilis prevalence in 2016 was 0.69% (95% confidence interval: 0.57-0.81%) resulting in a global CS rate of 473 (385-561) per 100,000 live births and 661,000 (538,000-784,000) total CS cases, including 355,000 (290,000-419,000) adverse birth outcomes (ABO) and 306,000 (249,000-363,000) non-clinical CS cases (infants without clinical signs born to un-treated mothers). The ABOs included 143,000 early fetal deaths and stillbirths, 61,000 neonatal deaths, 41,000 preterm or low-birth weight births, and 109,000 infants with clinical CS. Of these ABOs- 203,000 (57%) occurred in pregnant women attending ANC but not screened for syphilis; 74,000 (21%) in mothers not enrolled in ANC, 55,000 (16%) in mothers screened but not treated, and 23,000 (6%) in mothers enrolled, screened and treated. The revised 2012 estimates were 0.70% (95% CI: 0.63-0.77%) maternal prevalence, and 748,000 CS cases (539 per 100,000 live births) including 397,000 (361,000-432,000) ABOs. The estimated decrease in CS case rates between 2012 and 2016 reflected increased access to ANC and to syphilis screening and treatment.

CONCLUSIONS

Congenital syphilis decreased worldwide between 2012 and 2016, although maternal prevalence was stable. Achieving global CS elimination, however, will require improving access to early syphilis screening and treatment in ANC, clinically monitoring all women diagnosed with syphilis and their infants, improving partner management, and reducing syphilis prevalence in the general population by expanding testing, treatment and partner referral beyond ANC.

Decline in the seroprevalence of syphilis markers among first-time blood donors in Libreville (Gabon) between 2004 and 2016

Background

Very few studies have been conducted on the seroprevalence of syphilis in Gabon. According to the World Health Organization, the average seroprevalence of syphilis has declined from 5.5 to 1.1% in Central Africa. The aim of this study was to test the hypothesis that syphilis decreased in Gabon between 2004 and 2016 and to identify factors involved in this pattern by testing a large sample of first-time blood donors in the capital Libreville.

Methods

The detection of Treponema pallidum was done using a Rapid Plasma Reagin test (RPR) and confirmed by an ELISA test using the Biorad Syphilis Total Antibody EIA II kit or BioMerieux Trepanostika TP recombinant. Assays were performed by dedicated technicians according to manufacturers’ recommendations and following the laboratory standard operating procedures. Test results were manually transferred into the laboratory Excel files and hand-written in the laboratory logbook for syphilis testing. Logistic regression was used to assess the impact of sociodemographic characteristics on syphilis marker seroprevalence in both univariate and multivariable analysis. Odds ratios (OR) and 95% confidence intervals were calculated.

Results

The seroprevalence of syphilis markers was 8.4% (95% CI = 7.9–8.9) in 2004 and 2.4% (95% CI = 2.1–2.7) in 2016. The difference was significant [OR = 3.78; 95% CI (3.26–4.38); P < 0.001]. The decrease in syphilis seroprevalence was significant in both women and men and in each age group in univariate analysis. In multivariable analysis, controlling for all sociodemographic factors, the decrease in syphilis seroprevalence from 2004 to 2016 remained significant (OR = 3.29; 95% CI = 2.88–3.88, P < 0.001). The seroprevalence of syphilis decreased significantly in men compared to women and young donors compared to donors aged ≥36 years.

Conclusions

This study shows a significant decline in syphilis seroprevalence in first-time blood donors in Libreville, Gabon. Government actions, including multiple HIV prevention activities, are a likely part of this decline.

Adult gonorrhea, chlamydia and syphilis prevalence, incidence, treatment and syndromic case reporting in South Africa: Estimates using the Spectrum-STI model, 1990-2017

OBJECTIVES

To estimate trends in prevalence and incidence of syphilis, gonorrhea and chlamydia in adult men and women in South Africa.

METHODS

The Spectrum-STI tool estimated trends in prevalence and incidence of active syphilis, gonorrhea and chlamydia, fitting South African prevalence data. Results were used, alongside programmatic surveillance data, to estimate trends in incident gonorrhea cases resistant to first-line treatment, and the reporting gap of symptomatic male gonorrhea and chlamydia cases treated but not reported as cases of urethritis syndrome.

RESULTS

In 2017 adult (15-49 years) the estimated female and male prevalences for syphilis were 0.50% (95% CI: 0.32-0.80%) and 0.97% (0.19-2.28%), for gonorrhea 6.6% (3.8-10.8%) and 3.5% (1.7-6.1%), and for chlamydia 14.7% (9.9-21%) and 6.0% (3.8-10.4%), respectively. Between 1990 and 2017 the estimated prevalence of syphilis declined steadily in women and men, probably in part reflecting improved treatment coverage. For gonorrhea and chlamydia, estimated prevalence and incidence showed no consistent time trend in either women or men. Despite growing annual numbers of gonorrhea cases - reflecting population growth - the estimated number of first line treatment-resistant gonorrhea cases did not increase between 2008 and 2017, owing to changes in first-line antimicrobial treatment regimens for gonorrhea in 2008 and 2014/5. Case reporting completeness among treated male urethritis syndrome episodes was estimated at 10-28% in 2017.

CONCLUSION

South Africa continues to suffer a high STI burden. Improvements in access and quality of maternal, STI and HIV health care services likely contributed to the decline in syphilis prevalence. The lack of any decline in gonorrhea and chlamydia prevalence highlights the need to enhance STI services beyond clinic-based syndromic case management, to reinvigorate primary STI and HIV prevention and, especially for women, to screen for asymptomatic infections.

Prevalence and incidence estimates for syphilis, chlamydia, gonorrhea, and congenital syphilis in Colombia, 1995-2016

OBJECTIVES

To estimate adult (15-49 years old) prevalence and incidence of active syphilis, gonorrhea, and chlamydia, and incidence of congenital syphilis (CS) and adverse birth outcomes (ABOs) in Colombia, over 1995-2016.

METHODS

The Spectrum-STI epidemiological model tool estimated gonorrhea and chlamydia prevalences as moving averages across prevalences observed in representative general population surveys. For adult syphilis, Spectrum-STI applied segmented polynomial regression through prevalence data from antenatal care (ANC) surveys, routine ANC-based screening, and general population surveys. CS cases and ABOs were estimated from Spectrum's maternal syphilis estimates and proportions of women screened and treated for syphilis, applying World Health Organization case definitions and risk probabilities.

RESULTS

The Spectrum model estimated prevalences in 2016 of 0.70% (95% confidence interval (CI): 0.15%-1.9%) in women and 0.60% (0.1%-1.9%) in men for gonorrhea and of 9.2% (4.4%-15.4%) in women and 7.4% (3.5%-14.7%) in men for chlamydia, without evidence for trends over 1995-2016. The prevalence of active syphilis in 2016 was 1.25% (1.22-1.29%) in women and 1.25% (1.1%-1.4%) in men, decreasing from 2.6% (2.1%-3.2%) in women in 1995. Corresponding CS cases in 2016 (including cases without clinical symptoms) totaled 3 851, of which 2 245 were ABOs. Annual CS and ABO estimates decreased over 2008-2016, reflecting decreasing maternal prevalence and increasing cases averted through ANC-based screening and treatment.

CONCLUSIONS

The available surveillance and monitoring data synthesized in Spectrum-STI- and the resulting first-ever national STI estimates for Colombia-highlighted Colombia's persistently high STI burden. Adult syphilis and congenital syphilis are estimated to be falling, reflecting improving screening efforts. Strengthened surveillance, including with periodic screening in low-risk populations and future refined Spectrum estimations, should support planning and implementation of STI prevention and control, including CS elimination.

Syphilis prevalence trends in adult women in 132 countries - estimations using the Spectrum Sexually Transmitted Infections model

We estimated national-level trends in the prevalence of probable active syphilis in adult women using the Spectrum Sexually Transmitted Infections (STI) model to inform program planning, target-setting, and progress evaluation in STI control. The model fitted smoothed-splines polynomial regressions to data from antenatal clinic surveys and screening and representative household surveys, adjusted for diagnostic test performance and weighted by national coverage. Eligible countries had ≥1 data point from 2010 or later and ≥3 from 2000 or later from adult populations considered representative of the general female population (pregnant women or community-based studies). Between 2012 and 2016, the prevalence of probable active syphilis in women decreased in 54 (41%) of 132 eligible countries; this decrease was substantive (≥10% proportionally, ≥0.10% percentage-point absolute difference and non-overlapping 95% confidence intervals in 2012 and 2016) in 5 countries. Restricting eligible data to prevalence measurements of dual treponemal and non-treponemal testing limited estimates to 85 countries; of these, 45 countries (53%) showed a decrease. These standardized trend estimates highlight the need for increased investment in national syphilis surveillance and control efforts if the World Health Organization target of a 90% reduction in the incidence of syphilis between 2018 and 2030 is to be met.

Trends in Adult Chlamydia and Gonorrhea Prevalence, Incidence and Urethral Discharge Case Reporting in Morocco over 1995-2015-Estimates Using the Spectrum-Sexually Transmitted Infection Model

Trend estimations using the Spectrum-sexually transmitted infection (STI) model based on survey and surveillance data from Morocco showed declining gonorrhea and chlamydia prevalence and incidence in adults over 1995 to 2015. Supplemental digital content is available in the text.

Background

Evolving health priorities and resource constraints mean that countries require data on sexually transmitted infections (STI) trends to inform program planning and resource allocation.

Methods

The Spectrum modeling tool estimated prevalence and incidence of gonorrhea and chlamydia in Morocco's 15- to 49-year-old population, based on prevalence surveys. Incident cases, broken down between symptomatic and asymptomatic, and treated versus untreated, were compared with urethral discharge (UD) case reports, to estimate reporting completeness among treated UD cases.

Results

Gonorrhea prevalence was estimated at 0.37% (95% confidence interval [CI], 0.14–1.0%) in women and 0.32% (0.12–0.87%) in men in 2015; chlamydia prevalences were 3.8% (95% CI, 2.1–6.4%) and 3.0% (95% CI, 1.7–5.1%). Corresponding estimated numbers of new cases in women and men in 2015 were 79,598 (95% CI, 23,918–256,206) and 112,013 (95% CI, 28,700–307,433) for gonorrhea, and 291,908 (95% CI, 161,064–524,270) and 314,032 (95% CI, 186,076–559,133) for chlamydia. Gonorrhea and chlamydia prevalence had declined by an estimated 41% and 27%, respectively, over 1995 to 2015. Prevalence declines probably related to improved STI treatment coverage, and decreasing risk behaviors. Reporting completeness among treated UD cases was estimated at 46% to 77% in 2015. Reported UD cases corresponded to 13% of all estimated (symptomatic and asymptomatic) gonorrhea and chlamydia cases.

Conclusions

STI declines and improvements in treatment coverage are consistent with Morocco’s introduction of syndromic management in 2000, scale-up of prevention, and declining human immunodeficiency virus incidence. While gonorrhea is four-fold more common as cause of clinical UD cases than chlamydia, Morocco continues to suffer a large, untreated burden of chlamydia. Reliable monitoring of both STIs requires new periodic surveys and/or novel forms of affordable surveillance beyond high-risk populations.

Trends and Predictors of Syphilis Prevalence in the General Population: Global Pooled Analyses of 1103 Prevalence Measures Including 136 Million Syphilis Tests

Background

This study assessed levels, trends, and associations of observed syphilis prevalence in the general adult population using global pooled analyses.

Methods

A standardized database of syphilis prevalence was compiled by pooling systematically gathered data. Random-effects meta-analyses and meta-regressions were conducted using data from the period 1990-2016 to estimate pooled measures and assess predictors and trends. Countries were classified by World Health Organization region. Sensitivity analyses were conducted.

Results

The database included 1103 prevalence measures from 136 million syphilis tests across 154 countries (85% from women in antenatal care). Global pooled mean prevalence (weighted by region population size) was 1.11% (95% confidence interval [CI], .99-1.22). Prevalence predictors were region, diagnostic assay, sample size, and calendar year interacting with region. Compared to the African Region, the adjusted odds ratio (AOR) was 0.42 (95% CI, .33-.54) for the Region of the Americas, 0.13 (95% CI, .09-.19) for the Eastern Mediterranean Region, 0.05 (95% CI, .03-.07) for the European Region, 0.21 (95% CI, .16-.28) for the South-East Asia Region, and 0.41 (95% CI, .32-.53) for the Western Pacific Region. Treponema pallidum hemagglutination assay (TPHA) only or rapid plasma reagin (RPR) only, compared with dual RPR/TPHA diagnosis, produced higher prevalence (AOR >1.26), as did smaller sample-size studies (<500 persons) (AOR >2.16). Prevalence declined in all regions; the annual AORs ranged from 0.84 (95% CI, .79-.90) in the Eastern Mediterranean to 0.97 (95% CI, .97-1.01) in the Western Pacific. The pooled mean male-to-female prevalence ratio was 1.00 (95% CI, .89-1.13). Sensitivity analyses confirmed robustness of results.

Conclusions

Syphilis prevalence has declined globally over the past 3 decades. Large differences in prevalence persist among regions, with the African Region consistently the most affected.

Adult female syphilis prevalence, congenital syphilis case incidence and adverse birth outcomes, Mongolia 2000-2016: Estimates using the Spectrum STI tool

INTRODUCTION

Mongolia's health ministry prioritizes control of Sexually Transmitted Infections, including syphilis screening and treatment in antenatal care (ANC).

METHODS

Adult syphilis prevalence trends were fitted using the Spectrum-STI estimation tool, using data from ANC surveys and routine screening over 1997-2016. Estimates were combined with programmatic data to estimate numbers of treated and untreated pregnant women with syphilis and associated incidence congenital syphilis (CS) and CS-attributable adverse birth outcomes (ABO), which we compared with CS case reports.

RESULTS

Syphilis prevalence in pregnant women was estimated at 1.7% in 2000 and 3.0% in 2016. We estimated 652 CS cases, of which 410 ABO, in 2016. Far larger, annually increasing numbers of CS cases and ABO were estimated to have been prevented: 1654 cases, of which 789 ABO in 2016 - thanks to increasing coverages of ANC (99% in 2016), ANC-based screening (97% in 2016) and treatment of women diagnosed (81% in 2016). The 42 CS cases reported nationally over 2016 (liveborn infants only) represented 27% of liveborn infants with clinical CS, but only 7% of estimated CS cases among women found syphilis-infected in ANC, and 6% of all estimated CS cases including those born to women with undiagnosed syphilis.

DISCUSSION/CONCLUSION

Mongolia's ANC-based syphilis screening program is reducing CS, but maternal prevalence remains high. To eliminate CS (target: <50 cases per 100,000 live births), Mongolia should strengthen ANC services, limiting losses during referral for treatment, and under-diagnosis of CS including still-births and neonatal deaths, and expand syphilis screening and prevention programs.

Trends in adult chlamydia and gonorrhoea prevalence, incidence and urethral discharge case reporting in Mongolia from 1995 to 2016 - estimates using the Spectrum-STI model

OBJECTIVE

To estimate Mongolia's prevalence and incidence trends of gonorrhoea and chlamydia in women and men 15-49 years old to inform control of STIs and HIV, a national health sector priority.

METHODS

We applied the Spectrum-STI estimation model, fitting data from two national population surveys (2001 and 2008) and from routine gonorrhoea screening of pregnant women in antenatal care (1997 to 2016) adjusted for diagnostic test performance, male/female differences and missing high-risk populations. Prevalence and incidence estimates were then used to assess completeness of national case reporting.

RESULTS

Gonorrhoea prevalence was estimated at 3.3% (95% confidence interval, 1.6-3.9%) in women and 2.9% (1.6-4.1%) in men in 2016; chlamydia prevalence levels were 19.5% (17.3-21.9%) and 15.6% (10.0-21.2%), respectively. Corresponding new incident cases in women and men in 2016 totalled 60 334 (36 147 to 121 933) and 76 893 (35 639 to 254 913) for gonorrhoea and 131 306 (84 232 to 254 316) and 148 162 (71 885 to 462 588) for chlamydia. Gonorrhoea and chlamydia prevalence declined by an estimated 33% and 11%, respectively from 2001 to 2016.Comparing numbers of symptomatic and treated cases estimated by Spectrum with gonorrhoea case reports suggests that 15% of symptomatic treated gonorrhoea cases were reported in 2016; only a minority of chlamydia episodes were reported as male urethral discharge cases.

DISCUSSION

Gonorrhoea and chlamydia prevalence are estimated to have declined in Mongolia during the early 2000s, possibly associated with syndromic management in primary care facilities and improving treatment coverage since 2001 and scale up of HIV/STI prevention interventions since 2003. However, prevalence remains high with most gonorrhoea and chlamydia cases not treated or recorded in the public health system.

The prevalence and incidence of active syphilis in women in Morocco, 1995-2016: Model-based estimation and implications for STI surveillance

BACKGROUND

Evolving health priorities and resource constraints mean that countries require data on trends in sexually transmitted infections (STI) burden, to inform program planning and resource allocation. We applied the Spectrum STI estimation tool to estimate the prevalence and incidence of active syphilis in adult women in Morocco over 1995 to 2016. The results from the analysis are being used to inform Morocco's national HIV/STI strategy, target setting and program evaluation.

METHODS

Syphilis prevalence levels and trends were fitted through logistic regression to data from surveys in antenatal clinics, women attending family planning clinics and other general adult populations, as available post-1995. Prevalence data were adjusted for diagnostic test performance, and for the contribution of higher-risk populations not sampled in surveys. Incidence was inferred from prevalence by adjusting for the average duration of infection with active syphilis.

RESULTS

In 2016, active syphilis prevalence was estimated to be 0.56% in women 15 to 49 years of age (95% confidence interval, CI: 0.3%-1.0%), and around 21,675 (10,612-37,198) new syphilis infections have occurred. The analysis shows a steady decline in prevalence from 1995, when the prevalence was estimated to be 1.8% (1.0-3.5%). The decline was consistent with decreasing prevalences observed in TB patients, fishermen and prisoners followed over 2000-2012 through sentinel surveillance, and with a decline since 2003 in national HIV incidence estimated earlier through independent modelling.

CONCLUSIONS

Periodic population-based surveys allowed Morocco to estimate syphilis prevalence and incidence trends. This first-ever undertaking engaged and focused national stakeholders, and confirmed the still considerable syphilis burden. The latest survey was done in 2012 and so the trends are relatively uncertain after 2012. From 2017 Morocco plans to implement a system to record data from routine antenatal programmatic screening, which should help update and re-calibrate next trend estimations.

WORLD HEALTH ORGANIZATION GLOBAL HEALTH SECTOR STRATEGY ON SEXUALLY TRANSMITTED INFECTIONS: AN EVIDENCE-TO-ACTION SUMMARY FOR COLOMBIA

Curable and incurable sexually transmitted infections (STI) are acquired by hundreds of millions of people worldwide each year. Undiagnosed and untreated STIs cause a range of negative health outcomes including adverse birth outcomes, infertility and other long term sequelae such as cervical cancer. In 2016, the World Health Organization (WHO) launched the Global STI Strategy (2016-2021). The WHO Global STI Strategy's public health approach focuses on three causative organisms of STIs that need immediate action and for which cost-effective interventions exist: (a) Neisseria gonorrhoeae as a cause of infertility, a risk factor for coinfection with other STIs and because of increasing bacterial resistance to antibiotic treatment, (b) Treponema pallidum given the contribution of syphilis to adverse birth outcomes including stillbirth and neonatal death and (c) Human papillomavirus due to its link to cervical cancer. The range of actions recommended for countries includes: (a) strengthening surveillance, with program monitoring and progress evaluation, (b) STI prevention, (c) early diagnosis of STIs, (d) patient and partner management, and (e) approaches to reach the most vulnerable populations. This summary describes the WHO Global STI Strategy alongside findings from a STI surveillance workshop held in Colombia in May of 2017. Observations related to the Global STI Strategy and findings from the STI estimation workshop are described here for stakeholders in Colombia to consider as they identify opportunities to improve STI services and surveillance.

Pathways and progress to enhanced global sexually transmitted infection surveillance

Melanie Taylor and colleagues discuss global initiatives for surveillance of sexually transmitted diseases.

Costing of National STI Program Implementation for the Global STI Control Strategy for the Health Sector, 2016-2021

Introduction

In 2016 the World Health Assembly adopted the global strategy on Sexually Transmitted Infections (STI) 2016–2021 aiming to reduce curable STIs by 90% by 2030. We costed scaling-up priority interventions to coverage targets.

Methods

Strategy-targeted declines in Chlamydia trachomatis, Neisseria gonorrhoeae, Treponema pallidum and Trichomonas vaginalis were applied to WHO-estimated regional burdens at 2012. Syndromic case management was costed for these curable STIs, symptomatic Herpes Simplex Virus 2 (HSV-2), and non-STI vaginal syndromes, with incrementally expanding etiologic diagnosis. Service unit costs were multiplied with clinic attendances and people targeted for screening or prevention, by income tier. Human papilloma virus (HPV) vaccination and screening were costed for coverage increasing to 60% of 10-year-old girls for vaccination, and 60% of women 30–49 years for twice-lifetime screening (including clinical follow-up for positive screens), by 2021.

Results

Strategy implementation will cost an estimated US$ 18.1 billion over 2016–2021 in 117 low- and middle-income countries. Cost drivers are HPV vaccination ($3.26 billion) and screening ($3.69 billion), adolescent chlamydia screening ($2.54 billion), and antenatal syphilis screening ($1.4 billion). Clinical management—of 18 million genital ulcers, 29–39 million urethral discharges and 42–53 million vaginal discharges annually—will cost $3.0 billion, including $818 million for service delivery and $1.4 billion for gonorrhea and chlamydia testing. Global costs increase from $2.6 billion to $ 4.0 billion over 2016–2021, driven by HPV services scale-up, despite vaccine price reduction. Sub-Saharan Africa, bearing 40% of curable STI burdens, covers 44% of global service needs and 30% of cost, the Western Pacific 15% of burden/need and 26% of cost, South-East Asia 20% of burden/need and 18% of cost.

Conclusions

Costs of global STI control depend on price trends for HPV vaccines and chlamydia tests. Middle-income and especially low-income countries need increased investment, innovative financing, and synergizing with other health programs.