Worldwide prevalence of Chlamydia trachomatis in infertile women: A systematic review and meta-analysis

Abstract

Introduction

Chlamydia trachomatis (CT) infection is a prevalent sexually transmitted disease (STD). It seems that CT infections ascending to the uterus can result in serious reproductive health complications, including infertility. Therefore, this systematic review and meta-analysis was conducted to assess the worldwide prevalence of CT among infertile women.

Methods

A systematic search was conducted across three major databases, Medline (via PubMed), Web of Science, and Scopus, to identify eligible studies between 2010 and July 2025. Keywords such as “Chlamydia trachomatis,” “infertility,” “women,” and “prevalence “were used. The prevalence of CT among infertile women was estimated using random-effects model meta-analyses and reported with 95% confidence intervals (CIs). Subgroup analyses were conducted based on detection method and sample type. Meta-regression analysis was performed to evaluate the relationship between CT prevalence and either participants' age or year of publication.

Results

Thirty-eight studies, involving 14995 infertile women, were included in this study. The overall pooled prevalence of CT among infertile women was 24.1% (95% CI: 17.1–33.00). Regarding the diagnostic sample type, the highest prevalence of CT was observed in blood samples 45.7% (95% CI: 34.7–57.2), whereas the lowest was found in urine sample 10.8% (95% CI: 7.2–15.9). In terms of detection method, the highest prevalence of CT was reported using ELISA 26.9% (95% CI: 14.4–44.5), whereas the lowest prevalence was observed with the rapid test kit 7.9% (95% CI: 4–1.27). In endocervical samples, real-time PCR showed the highest prevalence among detection methods 20.5% (95% CI: 11.8–33.3) compared with other methods, indicating its high diagnostic sensitivity.

Conclusion

This finding indicates that the overall prevalence of CT among infertile women is relatively high, highlighting the importance of paying special attention to this pathogen in infertility assessments. Among diagnostic methods, ELISA showed the highest overall prevalence, while real-time PCR in endocervical samples demonstrated high diagnostic sensitivity, emphasizing its effectiveness for accurate detection in this sample type. Ultimately, routine and standardized CT screening in infertile women may facilitate early detection, timely intervention, and improved fertility outcomes.

1. Introduction

Chlamydia trachomatis (CT) infection is a prevalent sexually transmitted disease (STD) caused by a type of obligate intracellular, Gram-negative bacterium. Infections caused by this pathogen are a major public health challenge worldwide [1]. This bacterium targets mucosal epithelial cells found in the mouth, penis, vagina, and anus [2,3]. According to the World Health Organization (WHO), in 2020, there were approximately 128.5 million new cases of CT infection among adults aged 15 to 49 years globally. The estimated global prevalence of CT in this age group was approximately 4.0% in women and 2.5% in men [1].

CT infections frequently do not produce any noticeable symptoms, so many individuals remain unaware that they are infected, resulting in delayed treatment. A review study shows that about 60.7% of women with CT may not show symptoms [4]. Because of this, many infections go undiagnosed and untreated, increasing the risk of spreading the infection and developing complications [4,5]. Infections caused by CT that ascend the uterus can lead to serious reproductive health issues, such as infertility [6]. Infertility, as a common global condition, is defined as the inability to achieve a clinical pregnancy after at least one year of regular, unprotected sexual intercourse and affects about 1 in 6 people worldwide [7]. A report indicated that women who tested positive for CT infection had a 30% higher risk of infertility compared with women who consistently tested negative [9].

In addition, the effect of CT on infertility in women can mainly be due to conditions such as cervicitis, pelvic inflammatory disease (PID), and ectopic pregnancy. These complications increase the risk of damage to the reproductive organs, such as blocking or scarring the fallopian tubes, and interfere with fertility [6,[8], [9], [10]].

According to our knowledge, the existing literature reveals a notable deficiency of systematic reviews and meta-analyses specifically addressing the prevalence of CT infection in infertile women. So, given the importance of timely diagnosis and appropriate treatment of this infection conducting review studies to examine the prevalence of CT in the population of infertile women is of great significance. Such research can contribute to the development of effective prevention and treatment strategies and reduce the economic and psychological burden caused by infertility. Therefore, filling the existing research gap by conducting more review studies regarding the prevalence of infection in infertile women can lead to improved reproductive health and a reduction in related problems.

2. Methods

2.1. Search strategy

This systematic review and meta-analysis was conducted to assess the worldwide prevalence of CT among infertile women. The methodology, including data gathering, analysis, interpretation, and defining the research problem, followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, ensuring transparency and standardized reporting in accordance with established systematic review protocols [11]. In addition, the present study has been registered in the PROSPERO database under the registration number CRD420251139748.

A systematic search was conducted across three major databases, such as Medline (via PubMed), Web of Science, and Scopus, to identify eligible studies between 2010 and July 2025. Keywords such as “Chlamydia trachomatis,” “infertility”, “women,” and “prevalence “were selected based on Medical Subject Headings (MeSH) and were combined with Boolean operators AND and OR. The search strategy in Pubmed database was (Chlamydia trachomatis[Title/Abstract]) OR (C. trachomatis[Title/Abstract]) AND (Infertility[Title/Abstract])) OR (Sterility[Title/Abstract])) OR (Reproductive Sterility[Title/Abstract])) OR (Subfertility[Title/Abstract])) OR (Sub-Fertility[Title/Abstract])) AND (Female[Title/Abstract])) OR (Females[Title/Abstract])) OR (Women[Title/Abstract])) AND (Prevalence[Title/Abstract]. Additionally, to ensure a comprehensive search, the reference lists of relevant studies were carefully reviewed to identify any other potential research. Search strategies of other databases are shown in the S1 Table.

2.2. Inclusion/exclusion criteria

Studies meeting the following criteria were included in the review: cross-sectional studies which published in the English language, between 2010 and July 2025, Participants were women who had failed to conceive after at least one year of unprotected sexual intercourse or had clinically confirmed infertility diagnosed by a specialist, and reported CT prevalence using diagnostic tests. Studies were excluded if they were other study designs (e.g., clinical trials, letters to the editor, case reports, reviews, and books), lacked access to the full text, reported irrelevant or duplicate data.

2.3. Data selection and extraction

The literature search was conducted independently by two researchers, and all retrieved articles were imported into EndNote (version 20, Thomson Reuters) to identify and remove duplicate records. After eliminating duplicates, the titles and abstracts of the remaining studies were screened according to the inclusion criteria, and full texts were reviewed when necessary. In the next step, the full texts of the remaining articles were carefully assessed, and eligible studies were selected for data extraction and included in the final analysis. Articles were independently screened by two researchers (V.GH. and H.M.) based on the inclusion criteria, and any disagreements were resolved through consultation with a third researcher (M.T.). Finally, the required data, including the author's name, sample size, publication year, country of study, age of participants, prevalence of CT, type of sample, and diagnostic methods, were carefully and separately extracted by the two researchers (V.GH. and H.M.) to ensure accuracy and consistency (Table 1).

Table 1.

The characteristics of the included studies.

First author, Year (reference)	Country	Age (mean ± SD)	Sample size	Positive Chlamydia (n)	Detection method	Sample type	Quality assessment
Odelola, 2023 [40]	Nigeria	29.4 ± 5.1	147	94	ELISA	Blood	High
Subramanian, 2023 [16]	India	N/A	50	3	Real-time PCR	Endocervical	Moderate
Chen, 2021 [17]	China	34 ± 4.7	25	10	Real-time PCR	Endocervical	High
Surana, 2012 [18]	India	24.6 ± 6.5	50	30	ELISA	Blood	Moderate
Miron, 2013 [44]	Romania	N/A	176	42	Real-time PCR	Endocervical	High
Zhou, 2024 [15]	China	N/A	8221	309	ELISA	Endocervical	High
Beyuo, 2019 [41]	Ghana	34.6 ± 5.4	189	15	Rapid Test Kit	Endocervical	High
Abdo, 2023 [19]	United Arab Emirates	N/A	308	58	ELISA	Blood	High
Rajabpour, 2020 [20]	Iran	N/A	97	15	PCR	Endocervical	High
Gunyeli, 2011 [21]	Turkey	26.3 ± 5.7	53	4	ELISA	Endocervical	High
Hajikhani, 2012 [22]	Iran	N/A	51	6	PCR	Endocervical	Moderate
Mania-Pramanik, 2012 [23]	India	27.5 ± 6.3	264	49	PCR	Endocervical	Moderate
				38	ELISA
Dhawan, 2014 [24]	India	N/A	200	27	Real-time PCR	Endocervical	High
				23	PCR
				18	DIF
				13	ELISA
Sattari, 2017 [25]	Iran	N/A	184	66	ELISA	Blood	High
Haro-Cruz, 2011 [48]	Mexico	27.5 ± 4	152	24	PCR	Endocervical	Moderate
Lima Freitas, 2011 [49]	Brazil	32 ± 4.9	106	56	PCR	Endocervical	Moderate
Verweij, 2015 [45]	Netherlands	N/A	48	20	ELISA	Blood	Moderate
Bhardwaj, 2024 [26]	India	26.4 ± 3.7	169	15	PCR	Endocervical	Moderate
Alfarraj, 2015 [27]	Saudi Arabia	32.5 ± 4.4	100	8	Real-time PCR	Endocervical	Moderate
Kamel, 2013 [28]	Saudi Arabia	26.4 ± 4.8	640	96	ELISA	Endocervical	High
Paira, 2021 [50]	Argentina	N/A	1554	67	PCR	Endocervical	High
Yeow, 2016 [29]	Malaysia	N/A	68	56	PCR	Endocervical	High
Link, 2022 [51]	Brazil	N/A	203	22	PCR	Urine	Moderate
Li, 2017 [30]	China	29.3 ± 6.6	133	25	qPCR	Vaginal	High
Eksi, 2011 [31]	Turkey	N/A	93	2	DIF	Endocervical	High
Rawre, 2016 [32]	India	30.2 ± 4	477	75	PCR	Endocervical	High
Raoofi, 2011 [33]	Iran	26.7 ± 3.8	80	50	ELISA	Blood	Moderate
Sadeqi, 2022 [34]	Iran	N/A	200	94	Real-time PCR	Endocervical	Moderate
Sameni, 2022 [35]	Iran	N/A	65	9	PCR	Vaginal	Moderate
Ajani, 2019 [14]	Nigeria	N/A	21	10	PCR	Blood	Moderate
Yousuf, 2022 [36]	Pakistan	29 ± 3.4	100	6	PCR	Endocervical	Moderate
				13	DIF
Makled, 2012 [42]	Egypt	25.5 ± 3.9	80	30	ELISA	Blood	High
Kalsom, 2020 [39]	Malaysia	N/A	137	15	Real-time PCR	Endocervical	High
Cao, 2022 [37]	China	N/A	80	32	Real-time PCR	Endocervical	Moderate
Frej-Madrzak, 2011 [46]	Poland	N/A	108	41	DIF	Endocervical	Moderate
				17	ELISA
Hasan, 2024 [38]	Iraq	28.5 ± 6.3	60	33	ELISA	Blood	High
Ala, 2025 [43]	Nigeria	29.8 ± 7.5	135	37	PCR	Endocervical	High
Dooremalen, 2020 [47]	Netherlands	N/A	171	73	ELISA	Blood	High

Abbreviations: DIF: Direct immunofluorescence, ELISA: Enzyme-linked immunosorbent assay, PCR: Polymerase chain reaction, N/A: Not available.

2.4. Quality assessments

In this study, two reviewers (V.GH. and H.M.) independently assessed study quality using the nine-item Joanna Briggs Institute (JBI) Critical Appraisal tools to assess the methodological quality of studies. The responses to the questions were “yes,” “no,” “unclear,” and “not applicable,” with higher scores indicating a lower risk of bias. When the two reviewers disagreed, a third reviewer (P.M.) was consulted to resolve the discrepancy [12,13] (S2 Table).

2.5. Statistical analysis

The prevalence of CT among infertile women was estimated using random-effects model meta-analyses in Comprehensive Meta-Analysis (CMA) software (version 3.3.070). Prevalence was reported with 95% confidence intervals (CIs). Subgroup analyses were conducted to explore sources of heterogeneity based on detection method and sample type. Meta-regression analysis was performed to evaluate the relationship between CT prevalence and either participants' age or year of publication. Between-group heterogeneity was assessed using Cochrane's Q and the I² statistic. Potential publication bias was evaluated with Egger's weighted regression test. A p-value <0.05 was considered statistically significant in all analyses.

Sensitivity analyses were also carried out in CMA software. The “one study removed” (leave-one-out) method was applied to examine the influence of individual studies on the pooled prevalence estimates.

3. Results

Fig. 1 illustrates the study selection process for the present study. An extensive database search using predefined keywords initially identified 10,156 records. After duplicate articles were removed, the titles and abstracts of the remaining 4422 studies were screened. Based on the study objectives and predefined inclusion criteria, irrelevant articles were excluded, and the full texts of 253 studies were subsequently assessed. Ultimately, 38 studies, involving 14995 participants, were included in the meta-analysis. Disagreements between the two independent reviewers (V.GH. and H.M.) occurred in approximately in 3.95% during screening (n = 10 out of 253 articles). All discrepancies were minor and successfully resolved through discussion and consensus between the two reviewers, with no requirement for adjudication by a third party. Minimum and maximum samples were 21 [14] and 8221 [15] participants, respectively. Of the 38 included studies, 25 were conducted in Asia [[15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39]], 5 in Africa [14, [40], [41], [42], [43]], 4 in Europe [[44], [45], [46], [47]], and 4 in America [[48], [49], [50], [51]].

Fig. 1.

Systematic literature review flow diagram.

3.1. The prevalence of CT among infertile women

The pooled prevalence of CT in the infertile women was 24.1% (95% CI: 17.1–33.00) (Fig. 2). The highest prevalence was reported by Yeow et al. (82.4%) [29], whereas the lowest prevalence was reported by Eksi et al. (2.2%) [31].

Fig. 2.

The pooled prevalence of C. trachomatis among infertile women.

The null hypothesis, which assumed a pooled prevalence of zero, was rejected since the CIs for the summary effect did not include zero. This confirms a measurable prevalence of CT among the studied populations. The Q-value was 2042.86, substantially higher than the degrees of freedom (number of studies minus one = 37), demonstrating significant heterogeneity across studies. The I² statistic further showed that 98.19% of the observed variance was attributable to actual differences in effect sizes rather than chance (Fig. 2).

Sensitivity analyses revealed that excluding any individual study did not meaningfully affect the overall prevalence estimate (Fig. S1). These results suggest that the findings are stable and not disproportionately driven by a single study.

3.2. The prevalence of CT by sample type

Regarding the sample type used for CT detection in infertile women, endocervical swabs were used in 25 studies [[15], [16], [17],[20], [21], [22], [23], [24],[26], [27], [28], [29],31,32,34,36,37,39,41,43,44,46,[48], [49], [50]], blood in 10 studies [14,18,19,25,33,38,40,42,45,47], vaginal swabs in 2 studies [30,35], and urine in 1 study [51]. The subgroup analysis of the sample type indicated that the highest prevalence of CT was observed in blood samples 45.7% (95% CI: 34.7–57.2), whereas the lowest was found in urine sample 10.8% (95% CI: 7.2–15.9). This prevalence was 18.8% (95% CI: 11.9-28.4) for the endocervical sample and 17.3% (95% CI: 12.6-23.3) for the vaginal swab sample. Significant heterogeneity was also identified across sample types (Q-value = 37.77, p < 0.001) (Fig. 3).

Fig. 3.

The prevalence of C. trachomatis by sample type.

3.3. The prevalence of CT by detection method

In terms of the diagnostic methods utilized for CT detection among infertile women, polymerase chain reaction (PCR) was used in 15 studies [14,20,[22], [23], [24],26,29,32,35,36,43,[48], [49], [50], [51]], enzyme-linked immunosorbent assay (ELISA) in 15 studies [15,18,19,21,[23], [24], [25],28,33,38,40,42,[45], [46], [47]], real-time PCR in 8 studies [16,17,24,27,34,37,39,44], and direct immunofluorescence (DIF) in 4 studies [24,31,36,46]. In addition, one study employed the quantitative PCR (qPCR) method [30], and another study employed the rapid test kit [41]. The highest prevalence of CT in the infertile women was reported using ELISA 26.9% (95% CI: 14.4–44.5), whereas the lowest prevalence was observed with the rapid test kit 7.9% (95% CI: 4–1.27). In addition, this prevalence was 11.8% (95% CI:4-30) for DIF, 18.5% (95% CI: 11.5-28.5) for PCR, 18.8% (95% CI: 13-26.3) for qPCR, 20.5% (95% CI:11.8-33.3) for real time PCR. Significant heterogeneity was also detected across detection methods (Q-value = 13.71, p = 0.018) (Fig. 4).

Fig. 4.

The prevalence of C. trachomatis by detection method.

Furthermore, within each sample type, subgroup analysis was performed based on detection methods. Vaginal and urine samples were too limited to support subgroup meta-analysis. For blood, 9 of 10 studies used ELISA and only one used PCR, so a within-blood comparison by method was not possible. Endocervical samples, however, included enough studies to allow subgroup analyses by detection method. Among endocervical studies, pooled prevalences of CT were: PCR 18.2% (95% CI 10.4–29.9; 12 studies); ELISA 9.4% (95% CI 4.5–18.5; 10 studies); real-time PCR 20.5% (95% CI 11.8–33.3; 8 studies); DIF 11.8% (95% CI 4.0–30.1; 4 studies); and one rapid-test study 7.9% (95% CI 4.8–12.7). Heterogeneity across detection methods was not statistically significant but approached significance (Q = 9.07, p = 0.059) (Fig. 5).

Fig. 5.

Subgroup analysis by detection method in endocervical samples.

3.4. Meta-regression analysis of the prevalence of CT by year

The included studies were published between 2010 and 2025. Meta-regression analysis examining the association between publication year and the prevalence of CT revealed no significant relationship (p = 0.371) (Fig. 6).

Fig. 6.

Meta-regression analysis of the prevalence of C. trachomatis in the infertile women by year.

3.5. Meta-regression analysis of the prevalence of CT by age

The mean age of women in the included studies ranged from 24.6 to 34.6 years. Meta-regression analysis assessing the relationship between age and the prevalence of CT indicated no significant association (p = 0.421) (Fig. 7).

Fig. 7.

Meta-regression analysis of the prevalence of C. trachomatis in the infertile women by age.

3.6. Publication bias

The pooled prevalence of CT was used to assess potential publication bias. Due to the possibility of asymmetrical data distribution, Egger's linear regression test was conducted, revealing a significant publication bias (p = 0.002).

4. Discussion

This systematic review and meta-analysis, including 38 studies with 14995 infertile women, provides a clear picture of the substantial burden of CT infection in this population. Analysis of the selected studies indicates that CT prevalence among infertile women is a notable finding within the existing evidence. In this meta-analysis, the pooled prevalence of CT was 24.1%, with some included studies reporting rates as high as 82% [29], highlighting CT as a potentially impactful and sometimes overlooked factor in female infertility. Despite significant heterogeneity among studies, sensitivity analyses demonstrated that the pooled estimates were robust, and excluding any single study did not significantly alter the overall results. These findings indicate that, regardless of differences in diagnostic methods and study populations, the high prevalence of CT is a stable and reproducible finding, emphasizing its critical role in female infertility.

CT is one of the most common sexually transmitted infections (STIs) worldwide, and a hallmark of this infection is its asymptomatic nature in 75–80% of women [3,52], leading to delayed diagnosis and treatment. Chronic inflammation caused by CT damages the ciliated epithelium of the fallopian tubes and disrupts ovum transport. On the other hand, persistent infection can lead to irreversible scarring and tubal blockage, making CT-associated tubal factor infertility one of the most preventable causes of infertility in reproductive-aged women [6,53].

Compared to Neisseria gonorrhoeae and Treponema pallidum, CT is associated with a considerable burden of PID in women [54], with 10–15% of untreated cases progressing to this condition [55]. PID may also result in pelvic adhesions, tubal obstruction, ectopic pregnancy, and tubal infertility, and it often progresses silently and sub-clinically, highlighting the critical role of CT in tubal infertility [56].

The participants’ mean age in this meta-analysis ranged from 24.6 to 34.6 years, consistent with the global epidemiological pattern of CT. Evidence shows that the highest prevalence occurs in women under 25 years [57], a group at increased risk due to sexual activity, biological susceptibility of the cervical mucosa, and behavioral patterns. This age alignment strengthens the biological and demographic validity of the findings and demonstrates that the sample age distribution aligns with the population at highest risk, according to global studies.

Regarding sample types and detection methods, endocervical samples and PCR were most commonly used in the included studies, respectively. Despite the predominance of endocervical samples and PCR, the highest CT prevalence was observed in blood samples (45.7%) and with ELISA testing (26.9%), respectively.

Although endocervical culture has been a gold standard for the detection of CT in women (10), blood serology is particularly useful in women with limited access to endocervical sampling or a history of prior infection, enabling early detection and prevention of tubal damage and infertility [58]. ELISA detects specific CT antibodies or antigens and provides higher sensitivity, broad screening capability, and the ability to detect low-symptom infections [59]. The relatively high prevalence observed in this study with ELISA can be attributed to the inclusion of studies that used both antibody- and antigen-based ELISA assays for CT detection. Antibody-based ELISA methods may lead to higher prevalence estimates because antibodies can persist long after successful treatment, whereas antigen-based ELISA assays are more reflective of active infection [60]. Therefore, serological tests such as ELISA are not suitable for primary screening due to their inability to distinguish active from chronic infections. As a result, ELISA is valuable for detecting chronic, subclinical infections and long-term consequences such as PID and tubal infertility, as elevated antibody titers indicate previous exposure and potential lasting damage [40,61].

Additionally, the present study demonstrated that real-time PCR exhibits high diagnostic sensitivity for detecting CT in endocervical samples, with a prevalence of 20.5%, highlighting the substantial detection yield of this method in such specimens. These findings are consistent with evidence showing that nucleic acid–based diagnostic methods, including real-time PCR and other Nucleic Acid Amplification Tests (NAATs), outperform conventional approaches such as culture or antigen detection in identifying CT infections, owing to their higher analytical sensitivity and reduced risk of false-negative results in clinical specimens [62].

Overall, these findings, particularly the high prevalence of CT, alignment with global age patterns, the pathogen's established role in tubal damage, and the importance of sample type and diagnostic method, underscore the significance of targeted screening, early detection, and timely treatment in women of reproductive age, highlighting CT as a hidden but critical threat to female fertility and reproductive health.

5. Strengths and limitations

Strengths of this study include the review of a large number of studies, a substantial sample size (approximately 15,000 infertile women), and the estimation of CT prevalence across different sample types and detection methods, which enhances the reliability and statistical power of the findings. Limitations include study heterogeneity, limited access to all published studies and reports, and the lack of detailed clinical data for some participants, which may limit the precise interpretation of causes and risk factors. Nonetheless, the findings provide a reliable representation of CT prevalence and underscore the importance of early detection and targeted screening to prevent infertility. However, it is recommended that future research employ comparative study designs to assess CT prevalence in both fertile and infertile women, for a better understanding of its role in infertility.

6. Conclusion

This meta-analysis indicates a substantial worldwide prevalence of CT infection among infertile women, suggesting the importance of paying special attention to this infection in infertility assessments. Among diagnostic methods, ELISA showed the highest overall prevalence, while real-time PCR in endocervical samples demonstrated high diagnostic sensitivity, emphasizing its effectiveness for accurate detection in this sample type. The observed differences in prevalence across sample types and diagnostic methods highlight the influence of testing strategies on reported estimates. Ultimately, routine and standardized CT screening in infertile women may facilitate early detection, timely intervention, improved fertility outcomes, and more effective clinical management, and it should be considered in clinical practice.

CRediT authorship contribution statement

Vida Ghasemi: Writing – review & editing, Writing – original draft, Methodology, Data curation, Conceptualization. Mosayeb Rostamian: Writing – review & editing, Writing – original draft, Formal analysis. Mahboubeh Taebi: Writing – review & editing, Writing – original draft. Parnia Moradi: Writing – review & editing, Writing – original draft, Data curation. Hamid Motamedi: Writing – review & editing, Writing – original draft, Methodology, Data curation, Conceptualization.

Consent for publication

Not Applicable.

Ethics approval

This study received approval from the Ethics Committee of Asadabad School of Medical Sciences (ethics code: IR.ASAUMS.REC.1404.009). All subsequent procedures were reviewed and approved by the committee above.

Consent to participate

Not Applicable.

Availability of data and materials

The data that support the findings of this study are available upon request from the corresponding author (H.M.).

Funding

This research was supported by the Asadabad School of Medical Sciences (Research project number 197).

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Appendix A. Supplementary data

The following are the Supplementary data to this article:

Fig. S1.

Leave-one-out sensitivity analysis. The plot shows the pooled prevalence recalculated after sequential exclusion of each individual study. Exclusion of any single study did not materially alter the pooled estimate, indicating no single study had undue influence on the overall result.