Clinical Epidemiological Assessment of Sexually Transmitted Infections among Reproductive-age Adults in Rivers State, Nigeria

2026-06-13T11:37:30+00:00

Background: Sexually transmitted infections (STIs) cause substantial morbidity and adverse reproductive outcomes, yet population‑representative data from high‑burden settings like Rivers State, Nigeria, remain scarce. This study estimated the prevalence and correlates of curable and viral STIs among reproductive‑age adults using a clinical epidemiological approach.

Methods: A cross‑sectional analytic study enrolled 752 adults aged 15‑49 years from 15 health facilities and 10 community outreaches in Rivers State from February to October 2025. Structured interviews collected sociodemographic and behavioural data. Laboratory testing included nucleic acid amplification tests for Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and Trichomonas vaginalis (TV); serological tests for active syphilis, HSV‑2, hepatitis B surface antigen (HBsAg), and HIV. Survey‑weighted logistic regression identified correlates of any curable STI.

Results: Weighted prevalence of any curable STI was 16.9% (95% CI 14.2–19.9): CT 8.1%, TV 6.2%, NG 2.9%, active syphilis 1.7%. HSV‑2 seropositivity was 40.2%, HBsAg 6.1%, and HIV 3.5%. Most curable infections (61.2%) were asymptomatic. Independent correlates of any curable STI included age 20‑24 years (AOR 1.51; 95% CI 1.00–2.30), ≥2 sexual partners in the past year (AOR 1.82; 1.30–2.55), inconsistent condom use (AOR 1.46; 1.02–2.10), and prior STI diagnosis (AOR 1.69; 1.10–2.58). Model discrimination was acceptable (AUROC 0.73).

Conclusion: Curable STIs affect one in six reproductive‑age adults in Rivers State, with most infections asymptomatic. Behavioural factors align with global risk patterns. Aetiological testing substantially improves case detection over syndromic management. Integration of targeted nucleic acid amplification testing, risk‑stratified screening, and strengthened partner services is urgently needed.

A Multilevel Beta Mixed-effects Analysis of the Non-linear Evolution of HIV Prevalence in Females Aged 15-24 Years

2026-06-13T11:44:11+00:00

Background and Objectives: Despite significant strides being made in HIV prevention and treatment, adolescent girls and young women (AGYW) continue to be disproportionately affected by HIV infection globally. Many of the current studies on HIV prevalence globally have focused on linear or Gaussian-based models, which do not represent the bounded, skewed, nonlinear, and hierarchical nature of HIV prevalence data, and which may result in misleading inference and a lack of understanding of the dynamics of the HIV epidemic. The objective of this study was to describe long-term temporal trends and spatial variability in HIV prevalence among women aged 15-24 years at the population level with a sophisticated multilevel nonlinear modelling approach.

Method: A country-year panel dataset of 269 countries and territories in the World Development Indicators database (1990–2024) was analysed. HIV prevalence in the female population aged 15-24 years was the outcome variable. To model bounded prevalence proportions, multilevel beta mixed-effects regression was used, including natural cubic splines to model nonlinear temporal trends, random intercepts and slopes for country-specific heterogeneity, and repeated measurements. Model performance was evaluated by the Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), likelihood ratio tests, and simulation-based residual diagnostics.

Results: The spline beta mixed-effects model with random intercepts and random slopes was the best model fit, with values of AIC = −60,918.34 and BIC = −60,858.28, respectively, significantly better than the linear model (ΔAIC = 3,657.51). Nonlinear temporal effects were highly significant (χ² = 3663.51, p < 0.001) and showed a sharp increase in the epidemics in the 1990s followed by a gradual decrease since 2000. Each spline component was significantly associated (p < 0.001) with HIV trajectories, which were complex, nonlinear, and significantly different. There was evidence of significant variation and clusters of high burden of disease across countries, especially in sub-Saharan Africa. The overall model performance was satisfactory according to the diagnostic assessments, and there was no sign of any problems regarding dispersion, influential outliers or zero-inflation.

Conclusion: This study proposes a comprehensive hierarchical beta spline modelling framework that overcomes several important challenges in the currently available literature on HIV prevalence studies by being able to model cross-country heterogeneity, longitudinal dependence, nonlinear epidemic evolution and bounded outcomes. This information echoes the longstanding disparities of HIV burden between men and women and within young women. To advance towards the end of the HIV epidemic and SDGs 3 and 5, targeted adolescent-focused HIV prevention programmes need to be strengthened, sexual and reproductive health services need to be made more accessible and gender-responsive interventions need to be implemented in high-burden settings.

International STD Research & Reviews

Clinical Epidemiological Assessment of Sexually Transmitted Infections among Reproductive-age Adults in Rivers State, Nigeria

A Multilevel Beta Mixed-effects Analysis of the Non-linear Evolution of HIV Prevalence in Females Aged 15-24 Years