Spatial-temporal analysis of HIV/AIDS and syphilis in mainland China from 2007 to 2017

Spatio-temporal pattern and risk factors of HIV/AIDS prevalence in Zhejiang, China, from 2005 to 2022 using R-INLA

Background

The number of reported HIV/AIDS cases in the Zhejiang province, China, has increased drastically. However, spatial disparity and temporal trends in HIV/AIDS risk at the fine level remain unclear. We analyzed HIV/AIDS prevalence in Zhejiang, China to develop targeted HIV/AIDS prevention strategies and health resources.

Methods

This study included 56,699 HIV/AIDS patients reported in the Zhejiang province from 2005 to 2022. Data were obtained from the Zhejiang province Database of the National HIV/AIDS Comprehensive Response Information Management System. Spatial autocorrelation analysis was conducted using GeoDa 1.22, and factors influencing HIV/AIDS cases were identified through a Bayesian hierarchical Poisson regression model with the fast-computing R-INLA approach.

Results

Cases decreased from coastal to inland areas, while the standardized incidence ratio (SIR) and relative risk (RR) showed an overall increase. Key factors influencing RR included average diagnosed age (ADA), healthcare technical personnel per thousand people (HTP), male proportion (MP), GDP per capita (GDP), population density (PD), per capita disposable income (DPI), teachers per thousand people (TTP). The RR increased by 1.011, 0.989, 1.010, 0.997, 0.932, 0.990, and 0.830 per unit increase in ADA, HTP, MP, GDP, PD, DPI, and TTP, respectively. TTP was negatively associated with RR in high-prevalence regions but positively associated in low-prevalence regions. DPI showed a negative association in most regions but was not significant in upper-middle-prevalence areas.

Conclusion

HIV/AIDS risk varies significantly across the Zhejiang province, China. High-prevalence regions require targeted health education and rapid testing, while low-prevalence areas need improved healthcare infrastructure.

Spatial change, time tendency and projection to HIV/AIDS incidence in an eastern province of China

OBJECTIVES

As the second most populous province in China, it would have public implications to analyze spatial change, time tendency and prediction analysis of the acquired immunodeficiency syndrome (AIDS) epidemic in Shandong Province. Statistical projection study. Spatial autocorrelation model and spatiotemporal scanning analysis were used to describe the spatial and temporal distribution of HIV/AIDS incidence in Shandong Province from 2012 to 2022, and geographical weighted regression model and geographic detector model were used to analyze the influencing factors. The annual incidence rate of AIDS in Shandong Province from 2023 to 2030 was predicted by using the fitted Autoregressive Integrated Moving Average model (ARIMA). From 2012 to 2022, the incidence of AIDS in Shandong Province grows from 1/10 thousand to 2.48/10 thousand. Spatial regressions showed that the tertiary sector GDP ratio is the factor with the highest intensity of influence. AIDS incidence shows an overall decreasing trend from east to west across Shandong Province. It is predicted that the AIDS incidence rate in Shandong province will continue to rise from 2023 to 2030, with a projected rate of 6.33/10 thousand in 2030. From 2012 to 2022, the incidence of AIDS in Shandong Province increased and then decreased, and regional differences were revealed as well. It is predicted that the incidence of AIDS in Shandong Province would have an increasing trend from 2023 to 2030.

Prevalence of HIV/syphilis co-infection among men who have sex with men in China: a systematic review and meta-analysis

BACKGROUND

Men who have sex with men (MSM) are key populations for HIV and syphilis infection, and co-infection with both diseases significantly increases health risks. However, the co-infection of HIV/syphilis among this population in China has not been systematically evaluated. We aimed to conduct a meta-analysis to ascertain the prevalence of HIV/syphilis co-infection among MSM in China.

METHODS

We conducted a systematic literature search involving PubMed, Web of Science, CNKI and Wanfang to identify publications reporting HIV/syphilis co-infection among MSM in China. Our search encompassed articles available from the establishment of these databases up to December 31, 2022. Additionally, we examined the references of retrieved articles to identify additional relevant records. The random-effects model fitting Freeman-Tukey double arcsine transformation was employed to estimate the prevalence of HIV/syphilis co-infection and its 95% confidence interval (CI). Heterogeneity was assessed utilizing the I2 statistics and Cochran's Q test. To explore the potential sources of heterogeneity, we conducted subgroup and meta-regression analyses.

RESULTS

A total of 46 studies were included, with a total sample size of 50,187 MSM, including1,459 co-infected individuals. The pooled prevalence of HIV/syphilis co-infection among MSM in China was 2.7% (95% CI: 2.2-3.4%), with significant heterogeneity (I2 = 90.5%, Q = 474.65, P < 0.01). Across China's four regions, the Central region exhibited the highest co-infection prevalence (4.5%, 95% CI: 0.0-17.7%), followed by the Eastern region (3.1%, 95% CI: 2.4-3.9%) and Western region (2.4%, 95% CI: 1.8-3.1%). In contrast, the Northeast region reported the lowest co-infection prevalence (0.6%, 95% CI: 0.3-1.0%). Studies utilizing multiple sampling methods (4.7%, 95% CI: 3.6-6.0%) and recruiting MSM from sexually transmitted disease (STD) clinics (9.1%, 95% CI: 3.2-17.6%) showed higher prevalence of co-infection. Furthermore, the co-infection prevalence among MSM in China demonstrated a progressive increase with age.

CONCLUSION

The prevalence of HIV/syphilis co-infection among MSM in China was elevated, with certain regional disparities. Notably, the STD clinics attendees and older MSM were more likely to be co-infected. Urgent and targeted measures are needed to enhance interventions for these vulnerable populations to control HIV/syphilis co-infection.

Spatio-Temporal Distribution Characteristics of Syphilis: on the Scale of Towns (Streets) in Nantong City, Jiangsu Province, China

Objectives

To investigate the spatio-temporal distribution characteristics and changing trends of syphilis in Nantong city.

Methods

Joinpoint regression model, spatial autocorrelation and SaTScan spatio-temporal scanning were used to analyze the trend of syphilis reported incidence and spatio-temporal distribution characteristics in Nantong City.

Results

From 2013 to 2022, the reported incidence of syphilis in Nantong City increased at an average annual rate of 6.60%, of which the increase rate of latent syphilis was 13.45%. The high-high clustering areas were mainly distributed in 15 streets of Chongchuan District and all streets of Nantong Development Zone. SaTScan spatio-temporal scanning detected a total of two clustering areas, all from 2021 to 2022. The first cluster includes 24 streets with a radius of 16.27 km, and the second cluster includes 18 streets within a radius of 34.90 km.

Conclusion

The reported incidence of syphilis in Nantong City showed an increasing trend, mainly manifested as an increase in latent syphilis, and the reported incidence of syphilis in various towns (streets) showed obvious spatial clustering, and attention should be paid to key areas and targeted interventions should be formulated.

Serum homocysteine levels as a predictor of neurosyphilis among HIV-negative syphilis patients: A single-center retrospective study

This study investigates the differences in peripheral blood parameters between patients with non-neurosyphilis and neurosyphilis, aiming to identify potential serum biomarkers to predict the occurrence of neurosyphilis and avoid unnecessary lumbar punctures. A retrospective analysis was conducted on 110 HIV-negative syphilis patients in this study. We found that the serum homocysteine (Hcy) levels in the non-neurosyphilis group, asymptomatic neurosyphilis group, and symptomatic neurosyphilis group were 12.30 (10.45, 13.25), 17.50 (12.03, 26.28), and 15.70 (13.70, 20.20), respectively. The serum Hcy levels in the asymptomatic neurosyphilis group and symptomatic neurosyphilis group were significantly higher than those in the non-neurosyphilis group (P<0.05). The AUC for serum Hcy in diagnosing neurosyphilis was 0.861 (95% CI: 0.715-0.950), with a sensitivity and specificity of 98.47% and 71.43% respectively. The study indicated that serum Hcy levels serve as a potential biomarker to differentiate neurosyphilis from non-neurosyphilis.

High Incidence of syphilis seroconversion among people living with HIV in Hainan, south China

Globally, people living with HIV (PLHIV) are at a high risk of syphilis transmission, and Hainan Province has one of the highest syphilis rates in China. However, there is no targeted syphilis screening for HIV patients in Hainan, highlighting the need for data to guide public health interventions. This study aims to assess the incidence of seropositive syphilis and its associated factors among PLHIV. A retrospective cohort study was conducted at HIV care facilities in Haikou, China, recruiting adults living with HIV. The diagnosis of syphilis was confirmed through the TRUST and TPPA tests. Univariate logistic regression was employed to compare syphilis rates across groups, while multivariate logistic regression analysis was conducted to identify factors associated with syphilis infection. Of the 650 participants, 461 (70.9%) were men who have sex with men (MSM). The median age at HIV diagnosis was 28 years, with 154 (23.7%) testing positive for syphilis. The incidence of syphilis was the highest in individuals with prior STDs before HIV (43.1%), followed by those with suboptimal HIV antiretroviral therapy (ART) adherence (38.7%) and MSM (29.5%). The study identified that PLHIV who were diagnosed with HIV through voluntary testing (aOR:1.918, 95%CI:1.113-3.306), were MSM (aOR:2.648, 95%CI:1.269-5.524), had suboptimal HIV ART adherence (aOR:2.002, 95%CI:1.060-3.780), had a history of STDs before HIV (aOR:3.025, 95%CI:1.563-5.857), and had a longer duration of HIV ART (aOR:1.431, 95%CI:1.184-1.730) were at a higher risk of syphilis. The incidence of syphilis is high among PLHIV, especially in MSM and individuals with a history of STDs prior to their HIV diagnosis and suboptimal ART adherence, highlighting the need for targeted interventions and regular screening.

Evaluating the clinical utility of semi-quantitative luciferase immunosorbent assay using Treponema pallidum antigens in syphilis diagnosis and treatment monitoring

To assess the clinical applicability of a semi-quantitative luciferase immunosorbent assay (LISA) for detecting antibodies against Treponema pallidum antigens TP0171 (TP15), TP0435 (TP17), and TP0574 (TP47) in diagnosing and monitoring syphilis. LISA for detection of anti-TP15, TP17, and TP47 antibodies were developed and evaluated for syphilis diagnosis using 261 serum samples (161 syphilis, 100 non-syphilis). Ninety serial serum samples from 6 syphilis rabbit models (3 treated, 3 untreated) and 110 paired serum samples from 55 syphilis patients were used to assess treatment effects by utilizing TRUST as a reference. Compared to TPPA, LISA-TP15, LISA-TP17, and LISA-TP47 showed a sensitivity of 91.9%, 96.9%, and 98.8%, specificity of 99%, 99%, and 98%, and AUC of 0.971, 0.992, and 0.995, respectively, in diagnosing syphilis. Strong correlations (rs = 0.89-0.93) with TPPA were observed. In serial serum samples from rabbit models, significant differences in the relative light unit (RLU) were observed between the treatment and control group for LISA-TP17 (days 31-51) and LISA-TP47 (day 41). In paired serum samples from syphilis patients, TRUST titres and the RLU of LISA-TP15, LISA-TP17, and LISA-TP47 decreased post-treatment (P < .001). When TRUST titres decreased by 0, 2, 4, or ≥8-folds, the RLU decreased by 17.53%, 31.34%, 48.62%, and 72.79% for LISA-TP15; 8.84%, 17.00%, 28.37%, and 50.57% for LISA-TP17; 22.25%, 29.79%, 51.75%, and 70.28% for LISA-TP47, respectively. Semi-quantitative LISA performs well for syphilis diagnosis while LISA-TP17 is more effective for monitoring syphilis treatment in rabbit models and clinical patients.

Uncovering spatiotemporal development patterns of AIDS in China: A study using panel data with Joinpoint Regression analysis and Spatial Clustering

The HIV/AIDS epidemic in China is severe and complex. Comprehensive spatiotemporal analysis provides valuable insights for intervention policy formulation. Previous studies often overlooked local changes in time trends and regional disease development patterns. In this study, we propose a new spatiotemporal analysis method based on the Joinpoint Regression (JPR) model and K-means clustering to refine the division of stages in China's AIDS epidemic and differentiate geographical areas based on development patterns. We then use hotspot analysis to describe the current status of AIDS, presenting a comprehensive view of the epidemic in China from 2004 to 2018. JPR results show China's AIDS incidence generally increased during 2004-2018 (AAPC = 23.2), with a significant turning point in 2012. Time series feature clustering classifies the country into three regions: Southwest, Central and Eastern, and the other region. Each region corresponds to different epidemic causes and transmission pathways, informing targeted interventions. Hotspot analysis reveals the Southwest region as the most severely affected area, requiring intensified prevention and control efforts. This study offers a novel from both time and space dimensions for understanding and combating the AIDS epidemic, furnishing valuable references for policymakers in the further development of strategies.

Prevalence and disparities in sexual and reproductive health of women of reproductive age (20-49 years) in China: A national cross-sectional study

Background

Ensuring women's sexual and reproductive health (SRH) is a fundamental human right and key to 2030 agenda of the UN Sustainable Development Goals (SDGs), yet limited evidence exists on SRH in China, including national estimates and disparities of women's SRH experiences, gynaecological diseases, and sexually transmitted diseases (STDs).

Methods

A national cross-sectional survey based on a multistage stratified sampling from 15 provinces of China was performed from May 2019 to April 2021. A total of 12 815 reproductive-aged (20-49 years) women were involved. The SRH experiences (including age at menarche, age at first sexual activity, history of abortion, miscarriage, recurrent miscarriage, stillbirth, age at first delivery, types of delivery), the history of gynaecological diseases and STDs, as well as the environmental factors of participants were investigated. Human development index (HDI) was utilised to categorise and describe the socioeconomic status of the regions. The prevalence rates of diseases were compared among different HDI regions.

Results

We observed a decrease in the mean age at menarche, an increase in the proportion of women who became sexually active before 20, and a modest rise in mean age at first childbirth across generations. Age-standardised prevalence estimates of miscarriage, recurrent miscarriage, artificial abortion, ectopic pregnancy, and stillbirth were 9.3, 1.4, 55.7, 3.3, and 2.1%, respectively. Approximately 50% of participants reported a history of gynaecological diseases, with vulvovaginitis, cervicitis, and pelvic infection diseases being the most prevalent. The overall prevalence of STDs was estimated at 22.2‰, with mycoplasma genitalium infection having the highest reported prevalence. Disease prevalence varies across HDI regions.

Conclusions

Women's SRH behaviours and experiences have evolved, along with shifts in the spectrums of gynaecological diseases and STDs in China. Urgent recalibration of health care policies and disease control strategies is necessary, aligning them with women's changing SRH needs, ultimately ensuring their reproductive health and rights.

Diagnosing Tabes Dorsalis in HIV-Negative Patients: Clinical Features, Neuroimaging, and Laboratory Insights in the Modern Antibiotic Era

Background

Tabes dorsalis is a late manifestation of neurosyphilis, characterized by progressive ataxia, lightning pains, loss of proprioception, and urinary incontinence. The absence of a definitive diagnostic standard and the non-specific clinical manifestations have led to a significant rate of misdiagnoses.

Methods

Hospitalized patients with tabes dorsalis at Peking Union Medical College Hospital between January 2010 and December 2023 were reviewed.

Results

A total of 13 patients were included, with 10 males and 3 females. The median age was 50 years (range, 34-64). The most frequent initial symptoms were limb numbness (30.8%) and lightning pains (30.8%). Eleven patients (84.6%) received misdiagnoses prior to the final diagnosis. The most frequently observed physical sign was positive Romberg's sign (84.6%). Notably, Argyll Robertson pupil was presented in 7 subjects (53.8%). Serological tests revealed positive rapid plasma regain (RPR) and Treponema pallidum particle agglutination (TPPA) for all patients. All CSF samples were TPPA-reactive. Intramedullary hyperintensity on T2-weighted imaging of spinal MRI was found in 5 patients (38.5%). All patients received anti-syphilitic treatment, with effective treatment recorded in five cases.

Conclusion

This study underscores the importance of neurological symptoms and signs in diagnosing tabes dorsalis. Individuals with progressive ataxia and positive Romberg's sign should be closely monitored for potential neurosyphilis. Integrating clinical features, laboratory tests, and neuroimaging could reduce misdiagnosis and expedite the initiation of anti-syphilitic therapy.

Real experience of caregivers of patients with HIV/AIDS from the perspective of iceberg theory: a qualitative research

OBJECTIVE

This study aimed to investigate the caregiving behaviours and supportive needs of caregivers of patients with HIV/AIDS and provide a basis for healthcare institutions to carry out caregiver interventions.

DESIGN

A purposive sampling method was used to select 11 caregivers of patients with HIV/AIDS in the Infectious Disease Department of a tertiary hospital in Nanjing, China, to conduct semistructured interviews. Colaizzi analysis was used to collate and analyse the interview data.

SETTING

All interviews were conducted at a tertiary hospital specialising in infectious diseases in Nanjing, Jiangsu Province.

PARTICIPANTS

We purposively sampled 11 caregivers of people with HIV/AIDS, including nine women and two men.

RESULTS

Analysing the results from the perspective of iceberg theory, three thematic layers were identified: behavioural, value and belief. The behavioural layer includes a lack of awareness of the disease, physical and mental coping disorders, and an increased sense of stigma; the values layer includes a heightened sense of responsibility, the constraints of traditional gender norms, the influence of strong family values and the oppression of public opinion and morality and the belief layer includes the faith of standing together through storms and stress.

CONCLUSION

Healthcare professionals should value the experiences of caregivers of patients with HIV/AIDS and provide professional support to improve their quality of life.

The prevalence of gestational syphilis in Malawi between 2014 and 2022: spatiotemporal modeling of population-level factors

Background

Mother-to-child transmission of syphilis remains high especially in the WHO AFRO region with a prevalence of 1.62%, resulting in a congenital syphilis rate of 1,119 per 100,000 live births. Elimination efforts can be supported by an understanding of the spatial and temporal changes in disease over time, which can identify priority areas for targeted interventions aimed at reducing transmission.

Methods

We collated routine surveillance data from health facilities and covariate data from demographic and health surveys conducted in Malawi between 2014 and 2022. We fitted a Bayesian hierarchical mixed model with spatial and temporally structured random effects to model the district-level monthly counts of maternal syphilis notifications as a function of individual- and district-level predictors. We then generated district-level spatiotemporally explicit risk profiles to estimate the effect of individual- and district-level covariates on maternal syphilis notifications and to identify hotspot areas.

Results

Overall, the national prevalence of maternal syphilis increased from 0.28% (95% CI: 0.27-0.29%) in 2014 to peaking in 2021 at 1.92% (95% CI: 1.89-1.96%). Between 2020 and 2022, there was a decline in prevalence, with the most significant decline seen in Zomba District (1.40, 95% CI: 1.12-1.66%). In regression models, a one percentage point increase in district-level antenatal HIV prevalence was associated with increased maternal syphilis (prevalence ratio [PR]: 1.15, 95% credible interval [CrI]: 1.10-1.21). There was also an increased prevalence of maternal syphilis associated with an increased district-level mean number of sex partners (PR: 1.05, 95% CrI: 0.80-1.37). The number of districts with a high prevalence of maternal syphilis also increased between 2014 and 2022, especially in the southern region, where most had a high probability (approaching 100%) of having high maternal syphilis (defined as relative risk >1 compared to the standard population of women aged 15-49 years) in 2022.

Conclusion

Maternal syphilis prevalence in Malawi shows an increasing upward trend, with an estimated six times relative increase between 2014 and 2022 (0.28% to 1.73%) and strong associations with higher district-level HIV prevalence. Controlling syphilis depends on reaching vulnerable populations at the sub-national level, which may be disproportionately affected. Our findings support the move to integrate the elimination of mother-to-child transmission (EMTCT) of syphilis programs with existing prevention of mother-to-child transmission (PMTCT) of HIV programs.

Neurosyphilis: insights into its pathogenesis, susceptibility, diagnosis, treatment, and prevention

Background and aim

Invasion of the central nervous system by Treponema pallidum can occur at any stage of syphilis. In the event that T. pallidum is not cleared promptly, certain individuals may experience progression to neurosyphilis, which manifests as cognitive and behavioral abnormalities, limb paralysis, and potentially fatal outcomes. Early identification or prevention of neurosyphilis is therefore crucial. The aim of this paper is to conduct a critical and narrative review of the latest information focusing exclusively to the pathogenesis and clinical management of neurosyphilis.

Methodology

To compile this review, we have conducted electronic literature searches from the PubMed database relating to neurosyphilis. Priority was given to studies published from the past 10 years (from 2013 to 2023) and other studies if they were of significant importance (from 1985 to 2012), including whole genome sequencing results, cell structure of T. pallidum, history of genotyping, and other related topics. These studies are classic or reflect a developmental process.

Results

Neurosyphilis has garnered global attention, yet susceptibility to and the pathogenesis of this condition remain under investigation. Cerebrospinal fluid examination plays an important role in the diagnosis of neurosyphilis, but lacks the gold standard. Intravenous aqueous crystalline penicillin G continues to be the recommended therapeutic approach for neurosyphilis. Considering its sustained prominence, it is imperative to develop novel public health tactics in order to manage the resurgence of neurosyphilis.

Conclusion

This review gives an updated narrative description of neurosyphilis with special emphasis on its pathogenesis, susceptibility, diagnosis, treatment, and prevention.

Temporal and Spatial Trends in HIV Positivity Rate for VCT Clinics - China, 2015-2022

Introduction

Human immunodeficiency virus (HIV) voluntary counseling and testing (VCT) clinics play a critical role in identifying and diagnosing HIV cases. This study aimed to describe the trend of HIV positivity rate (HPR) among Chinese VCT clinics between 2015 and 2022.

Methods

This study utilized data from the China Information System for Disease Control and Prevention to analyze the trend in the HPR for VCT clinics from 2015 to 2022. The HPR was calculated by dividing the number of newly-reported HIV cases by the number of HIV tests, multiplied by 100%. To identify temporal and spatial trends in the HPR, we employed joinpoint regression analysis and the Getis-Ord hotspot analysis.

Results

From 2015 to 2022, VCT clinics in China performed a total of 22,075,386 HIV tests, leading to the identification of 260,353 HIV cases, resulting in a HPR of 1.18%. The HPR consistently declined over the study period, with an average annual percent change (AAPC) of -7.5% (95% confidence interval: -12.6%, -2.2%, P<0.05). The number of HPR hotspots also decreased from 41 in 2015 to 23 in 2022. These HPR hotspots were primarily located in Yunnan, Sichuan, Guangdong, and Guangxi provincial-level administrative divisions (PLADs). Among the 31 PLADs, 16 showed a significant decrease in HPR during the study period (AAPC<0, PAAPC<0.05).

Conclusions

VCT clinics in China have played a significant role in identifying HIV cases. The declining HPR observed in these clinics may indicates the progress has been made in some degree in mitigating HIV among high-risk populations. Therefore, it is crucial to further improving the utilization of VCT clinics for HIV testing.

Associated Factors of Sexual Initiation among Male Vocational High School Students in Zhejiang Province, China: A Cross-sectional Study

AIMS

This study aims to investigate the factors associated with sexual initiation among male vocational high school students (MVHSS) in Zhejiang Province, and provide a scientific basis for preventing unsafe sexual behavior and sexual health issues among adolescents.

BACKGROUND

The prevalence of sexual behavior among young students has risen significantly in recent years. Contracting HIV poses a serious physical and psychological burden on young individuals and their families. Thus, it is imperative to promptly and effectively address the spread of HIV among young people.

OBJECTIVES

The objectives of this study are to investigate the demographic characteristics of male vocational high school students (MVHSS) who have engaged in sexual activity and to identify associated factors, such as sexual attitudes and lifestyle, that may influence sexual initiation among this population, and to offer recommendations for interventions and policy development aimed at promoting healthy sexual behaviors among MVHSS.

METHODS

A survey was conducted among vocational high school students in grades one and two in Zhejiang Province. Variables that were statistically significantly associated with sexual initiation in bivariate analyses were included in a multivariate logistic regression model, which adopted a backward elimination procedure with a p-value > 0.10 as the exclusion criterion. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to describe the relationship between dependent and outcome variables., Results: Of the 1032 male participants, 17.4% had initiated sexual behavior. The multivariate analysis results indicated that those who were frequent smokers (adjusted OR[AOR] =4.89, 95% CI: 2.36-10.13), those who reported having been in love (AOR=2.86, 95% CI: 1.84-4.44), those currently in love (AOR=4.47, 95% CI: 2.68-7.45), those willing to have sex with a high school student (AOR =2.63, 95% CI: 3.31-6.50), those willing to pay for sex (AOR =1.90, 95% CI: 1.10-3.27), and those who had received sex education and STDs/AIDS prevention education in school (AOR =2.21, 95% CI: 1.53-3.18) were more likely to initiate sexual behavior.

CONCLUSION

Sexual attitudes among MVHSS are liberal, and the prevalence of sexual initiation is high. Interventions targeted at improving sexual safety education, reducing the rate of early initiation of sexual behavior, and promoting condom use among students must be implemented to reduce the risk of HIV infections and STDs among sexually active MVHSS.

Scaling law characteristics and spatiotemporal multicomponent analysis of syphilis from 2016 to 2022 in Zhejiang Province, China

Background

Syphilis has caused epidemics for hundreds of years, and the global syphilis situation remains serious. The reported incidence rate of syphilis in Zhejiang Province has ranked first in the province in terms of notifiable infectious diseases for many years and is the highest in China. This study attempts to use the scaling law theory to study the relationship between population size and different types of syphilis epidemics, while also exploring the main driving factors affecting the incidence of syphilis in different regions.

Methods

Data on syphilis cases and affected populations at the county level were obtained from the China Disease Control and Prevention Information System. The scaling relationship between different stages of syphilis and population size was explained by scaling law. The trend of the incidence from 2016 to 2022 was tested by the joinpoint regression. The index of distance between indices of simulation and observation (DISO) was applied to evaluate the overall performance of joinpoint regression model. Furthermore, a multivariate time series model was employed to identify the main driving components that affected the occurrence of syphilis at the county level. The p value less than 0.05 or confidence interval (CI) does not include 0 represented statistical significance for all the tests.

Results

From 2016 to 2022, a total of 204,719 cases of syphilis were reported in Zhejiang Province, including 2 deaths, all of which were congenital syphilis. Latent syphilis accounted for 79.47% of total syphilis cases. The annual percent change (APCs) of all types of syphilis, including primary syphilis, secondary syphilis, tertiary syphilis, congenital syphilis and latent syphilis, were - 21.70% (p < 0.001, 95% CI: -26.70 to -16.30), -16.80% (p < 0.001, 95% CI: -20.30 to -13.30), -8.70% (p < 0.001, 95% CI: -11.30 to -6.00), -39.00% (p = 0.001, 95% CI: -49.30 to -26.60) and - 7.10% (p = 0.008, 95% CI: -11.20 to -2.80), respectively. The combined scaling exponents of primary syphilis, secondary syphilis, tertiary syphilis, congenital syphilis and latent syphilis based on the random effects model were 0.95 (95% CI: 0.88 to 1.01), 1.14 (95% CI: 1.12 to 1.16), 0.43 (95% CI: 0.37 to 0.49), 0.0264 (95% CI: -0.0047 to 0.0575) and 0.88 (95% CI: 0.82 to 0.93), respectively. The overall average effect values of the endemic component, spatiotemporal component and autoregressive component for all counties were 0.24, 0.035 and 0.72, respectively. The values of the autoregressive component for most counties were greater than 0.7. The endemic component of the top 10 counties with the highest values was greater than 0.34. Two counties with value of the spatiotemporal component higher than 0.1 were Xihu landscape county and Shengsi county. From 2016 to 2022, the endemic and autoregressive components of each county showed obvious seasonal changes.

Conclusion

The scaling exponent had both temporal trend characteristics and significant heterogeneity in the association between each type of syphilis and population size. Primary syphilis and latent syphilis exhibited a linear pattern, secondary syphilis presented a superlinear pattern, and tertiary syphilis exhibited a sublinear pattern. This suggested that further prevention of infection and transmission among high-risk populations and improvement of diagnostic accuracy in underdeveloped areas is needed. The autoregressive components and the endemic components were the main driving factors that affected the occurrence of syphilis. Targeted prevention and control strategies must be developed based on the main driving modes of the epidemic in each county.