Abstract
Background: Correctly estimating the prevalence of sexually transmitted infections (STIs) is crucial for monitoring and managing these diseases effectively. Objectives: This study aimed to estimate the prevalence of STI syndromes and evaluate the surveillance systems for STIs in Marvdasht. Methods: We conducted a cross-sectional study in 2018 involving a population-based random sample of 3 879 participants aged 18-50 in Marvdasht city. Genital ulcers and secretions in both genders were used as the primary outcomes to assess the completeness of the system and calculate the correction factor. A mathematical model was developed to estimate the correction factor for the prevalence of selected syndromes in each gender. The correction factor was determined by dividing the cases estimated through the mathematical model by the cases reported by the surveillance systems. Results: The estimated prevalence (with 95% confidence intervals [CI]) of urethral discharge in men and women, based on the model, was 25.32% (23.08 - 27.56) and 47.03% (39.93 - 54.13), respectively, and for genital ulcers, it was 5.16% (4.06 - 6.86) for men and 15.50% (9.5 - 21.5) for women. In both genders and for both syndromes, the reported prevalence by the care system (men: Discharge 0.09% [0.07 - 0.11], ulcer 0.04% [0.03 - 0.06]; women: Discharge 0.12% [0.1 - 0.15], ulcer 0.19% [0.16 - 0.22]) was severely underestimated. The highest and lowest underreporting correction ratios in the national STI monitoring system were observed for urethral discharge in men (124.5) and genital ulcers in women (7.26), respectively. Conclusions: The study revealed that the reported prevalence of STI syndromes in Iran is significantly underestimated compared to the actual prevalence in the population. Fundamental revisions are necessary to enhance the system's validity and completeness in detecting and reporting STIs.