Changing trends in Chlamydia and gonorrhea infections among female sex workers in Southern China: a surveillance data analysis spanning 2019 to 2022.

BACKGROUND: Female sex workers (FSW) are particularly vulnerable to chlamydia and gonorrhea infections. However, there were few studies that detail the evolving patterns of chlamydia and gonorrhea among Chinese FSW. Therefore, our study endeavors to assess the prevalence of chlamydia and gonorrhea epidemics within FSW, investigate their changing trends and scrutinize associated factors. METHODS: In 2019, China instituted a sentinel surveillance network focused on FSW in Guangdong Province. This network conducted an annual serial cross-sectional survey spanning from April to August. All analyses are predicated on surveillance data accumulated between 2019 and 2022. RESULTS: The prevalence of chlamydia increased from 10.1 to 12.3%, exhibiting an annual percentage shift of 6.8%. Conversely, the prevalence of gonorrhea dwindled from 2.0 to 1.3%, marking an annual percentage decline of 13.4% (P < 0.001). After adjusting for covariates, chlamydia exhibited associations with having household registration in other provinces (adjusted odds ratio (aOR = 0.55)), displaying symptoms of sexually transmitted infections (STIs) (aOR = 1.65) and infected with gonorrhea (aOR = 5.68). In parallel, gonorrhea demonstrated associations with providing oral sex to clients (aOR = 3.74), manifesting STIs symptoms (aOR = 4.27) and those infected with chlamydia (aOR = 5.43). CONCLUSIONS: Our observations underscore the imperative to implement a comprehensive intervention strategy concentrating on chlamydia, while simultaneously fortifying endeavors to expand the scope of gonorrhea prevention services.

Online commercial sex-seeking among female sex workers in south China: a cross-sectional study.

BACKGROUND: Online communication platforms have the potential to facilitate commercial sex among female sex workers (FSW), increasing the risk of contracting sexually transmitted diseases (STD). This study aimed to describe the patterns of online commercial sex-seeking and examine the associated factors among FSW in China. METHODS: A venue-based cross-sectional study was conducted in five cities in Guangdong Province, China, between April and October 2020. Data on socio-demographic characteristics, sexual behaviors, and online commercial sex-seeking patterns were collected through face-to-face interviews. Venous blood and urine samples were collected for STD testing. Univariate and multivariable logistic regressions were used to explore the factors associated with online commercial sex-seeking. RESULTS: A total of 1155 FSW were recruited in physical venues for this study. Among them, 33.42% reported ever using online applications to seek commercial sex. The prevalence of HIV, syphilis, gonorrhea, chlamydia, and STD was 0.26%, 1.30%, 4.40%, 15.54%, and 18.39%, respectively, among FSW who had ever used both physical and online venues to seek commercial sex, which was higher than among FSW who had never sought commercial sex online. Multivariable logistic regression indicated that FSW who used online platforms to seek commercial sex were more likely to have STD (adjusted odds ratio (aOR) = 1.48, 95%CI: 1.05-2.09), experience unintended pregnancies due to commercial sex (aOR = 1.78, 95%CI: 1.21-2.62), be diagnosed as infertile (aOR = 3.20, 95%CI: 1.42-7.21), and undergo abortions (aOR = 1.69, 95%CI: 1.29-2.20). CONCLUSION: A significant proportion of FSW who practiced in physical venues in China engaged in seeking commercial sex online, and this behavior is positively correlated with both STD and reproductive health outcomes. Given the high prevalence of online sex-seeking, it is crucial to provide a wide range of internet-based healthcare interventions and reproductive health services to Chinese FSW.

Early syphilis in Guangzhou, China: presentation, molecular detection of Treponema pallidum , and genomic sequences in clinical specimens and isolates obtained by rabbit infectivity testing.

Background: The global resurgence of syphilis requires novel prevention strategies. Whole genome sequencing (WGS) of Treponema pallidum ( TPA ) using different specimen types is essential for vaccine development. Methods: Patients with primary (PS) and secondary (SS) syphilis were recruited in Guangzhou, China. We collected ulcer exudates and blood from PS participants, and skin biopsies and blood from SS participants for TPA polA polymerase chain reaction (PCR); ulcer exudates and blood were also used to isolate TPA strains by rabbit infectivity testing (RIT). TPA WGS was performed on 52 ulcer exudates and biopsy specimens and 25 matched rabbit isolates. Results: We enrolled 18 PS and 51 SS participants from December 2019 to March 2022. Among PS participants, TPA DNA was detected in 16 (89%) ulcer exudates and three (17%) blood specimens. Among SS participants, TPA DNA was detected in 50 (98%) skin biopsies and 27 (53%) blood specimens. TP A was isolated from 48 rabbits, with a 71% (12/17) success rate from ulcer exudates and 69% (36/52) from SS bloods. Twenty-three matched SS14 clade genomes were virtually identical, while two Nichols clade pairs had discordant tprK sequences. Forty-two of 52 unique TPA genomes clustered in an SS14 East Asia subgroup, while ten fell into two East Asian Nichols subgroups. Conclusions: Our TPA detection rate was high from PS ulcer exudates and SS skin biopsies and over 50% from SS whole blood, with RIT isolation in over two-thirds of samples. Our results support the use of WGS from rabbit isolates to inform vaccine development. Summary: We performed Treponema pallidum molecular detection and genome sequencing from multiple specimens collected from early syphilis patients and isolates obtained by rabbit inoculation. Our results support the use of whole genome sequencing from rabbit isolates to inform syphilis vaccine development.

Evaluation of Chlamydia trachomatis screening from the perspective of health economics: a systematic review.

Background: Most Chlamydia trachomatis (CT) infections are asymptomatic. The infection can persist and lead to severe sequelae. Therefore, screening for CT can primarily prevent serious sequelae. Aim: To systematically evaluate CT screening from the perspective of health economics, summarize previous findings from different target populations, and make practical recommendations for developing local CT screening strategies. Methods: PubMed, Web of Science, Embase, Cochran Library, and National Health Service Economic Evaluation Database (Ovid) were searched from January 1, 2000, to March 4, 2023. Studies reporting the cost-effectiveness, cost-benefit, or cost-utility of CT screening were eligible to be included. A narrative synthesis was used to analyze and report the results following the PRISMA guidelines. The Consensus on Health Economic Criteria (CHEC) list was used to assess the methodological quality of included studies. Results: Our review finally comprised 39 studies addressing four populations: general sexually active people (n = 25), pregnant women (n = 4), women attending STD and abortion clinics (n = 4), and other high-risk individuals (n = 6). The total number of participants was ~7,991,198. The majority of studies assessed the cost-effectiveness or cost-utility of the screening method. The results showed that the following screening strategies may be cost-effective or cost-saving under certain conditions: performing CT screening in young people aged 15-24 in the general population, military recruits, and high school students; incorporating CT screening into routine antenatal care for pregnant women aged 15-30; opportunistic CT screening for women attending STD and abortion clinics; home-obtained sampling for CT screening using urine specimens or vaginal swab; performing CT screening for 14-30-year-old people who enter correctional institutions (i.e., jail, detention) as soon as possible; providing CT screening for female sex workers (FSWs) based on local incidence and prevalence; adding routine CT screening to HIV treatment using rectal samples from men who have sex with men (MSM). Conclusion: We found that CT screening in general sexually active people aged 15-24, military recruits, high school students, pregnant women aged 15-30, women attending STD and abortion clinics, people entering jail, detention, FSWs, and MSM has health economic value. Due to the different prevalence of CT, diversities of economic conditions, and varying screening costs among different populations and different countries, regions, or settings, no uniform and standard screening strategies are currently available. Therefore, each country should consider its local condition and the results of health economic evaluations of CT screening programs in that country to develop appropriate CT screening strategies.

Exploring causal mechanisms and essential factors in the prevention and control of chlamydia in Guangdong, Southern China: a study protocol.

BACKGROUND: Chlamydia Trachomatis (CT) is among the most prevalent sexually transmitted diseases (STDs) globally. According to the World Health Organization, more than 131 million people get infected with CT annually. CT is usually transmitted via sexual contact or perinatal exposure and can result in severe long-term complications. In developing nations, particularly, the prevention and control of CT is challenging. Hence, this study will explore the feedback mechanisms of chlamydia prevention and control, as well as identify the essential factors affecting the control and prevention of this infection in China. METHODS: Our study will employ a mixed-methods research design that encompasses both qualitative and quantitative methods. Firstly, we will develop a causal loop diagram (CLD) based on the literature review and optimize it via in-depth interviews with stakeholders. Additionally, we will utilize a quantitative method called MICMAC(Impact Matrix Cross-Reference Multiplication Applied to a Classification tool) to obtain consensus among different stakeholders and pinpoint the key information. Next, the CLD will be transformed into a system dynamics model (SDM) to evaluate the feedback mechanisms within the CLD. The causality in the CLD will be modeled using mathematical equations, which facilitate the transformation into an SDM. As such, we will be able to analyze the dynamic behavior of the system and its response to different decisions. DISCUSSION: Our study offers a systematic perspective on the control and prevention of chlamydia infection through system dynamics modeling, examining the dynamic properties and background factors of the system. The creation of the CLD affords stakeholders the chance to comprehend the functionality of their relationships and improve cooperation. Consequently, by evaluating the outcomes of these simulations, it will be possible to analyze and determine potential interventions and their effects on chlamydia infections. This modeling approach can help us gain insight into the dynamic characteristics of the system, evaluate the potential outcomes of different decisions, and design control strategies to either stabilize the system or adjust its behavior.

HIV/STD prevalence and test uptake among african in Guangzhou, China: an analysis of data from hospital-based surveillance.

Human immunodeficiency virus (HIV) and sexually transmitted diseases (STDs) cause substantial morbidity and mortality both in African and China. However, there is limited data available on the prevalence of HIV/STDs and the uptake of testing experience ever during in China among African migrants. A venue-based survey was conducted at a tertiary hospital in Guangzhou to investigate the prevalence of HIV/STDs through laboratory testing and identify the associated factors. A total of 200 eligible participants completed the survey and bring into the analysis from April to October 2019, and the temporary visitors were excluded. The prevalence rates of HIV, syphilis, NG, CT, and HBsAg among the participants were 1.0%, 2.5%, 1.0%, 1.5%, and 5.5%, respectively. The overall reported rate of HIV/STD testing was 37.0%, with rates of 23.0% for HIV, 16.5% for syphilis, 12.5% for NG, 6.5% for genital herpes, 5.0% for condyloma acuminata, and 2.5% for CT. HIV/STD testing was associated with living environment in Guangzhou, having medical insurance in China, and utilizing health services in China in the past year. HIV/STDs are prevalent among Africans in Guangzhou, and the epidemic is likely to spread due to a significant proportion of unprotected sexual behaviors and low rates of HIV/STD testing. Urgent interventions, including targeted health education, promotion of health service utilization, and active surveillance of HIV/STDs, are needed to reduce the risk of HIV/STD transmission.

HCV knowledge and attitudes among HIV-negative MSM and MSM living with HIV in China: results from a cross-sectional online survey.

BACKGROUND: Men who have sex with men (MSM) are at high risk of hepatitis C virus (HCV) infection, especially for those living with human immunodeficiency virus (HIV). Learning about knowledge of and attitudes towards HCV is essential to inform health promotion interventions development. This is one of very limited studies to examine the level of knowledge and attitudes towards HCV and their determinants among HIV-negative MSM and MSM living with HIV in China. METHODS: A cross-sectional survey was conducted across seven provinces in China from December 2021 to January 2022. All the MSM living with HIV were recruited offline, whereas the recruitment ratio for HIV-negative MSM was half online and half offline. Data on socio-demographic characteristics, sexual behaviors, knowledge about HCV, and attitude towards HCV from participants were collected through the online survey. Univariate and multivariable logistic regressions were used to determine the associated factors. RESULTS: Only 39.3% (33/84) of HIV-negative men and 44.0% (37/84) of men living with HIV had a good level knowledge about HCV. Nearly one-third (32.1%, 27/84) of HIV-negative men and 41.7% (35/84) of men living with HIV reported a positive attitude towards HCV. For HIV-negative men, positive attitude towards HCV was associated with the multiple sexual partners (aOR: 5.8, 95%CI:1.9-18.1) and the use of recreational substances (aOR: 3.1, 95%CI: 1.0-9.4). For men living with HIV, knowledge about HCV was associated with disclosing sexual orientation to healthcare providers, family or friends (aOR: 7.0, 1.9-26.0), the multiple sexual partners (aOR: 0.2, 0.1-1.0), the use of recreational substances (aOR: 3.7, 95%CI: 1.1-13.1) and the HBV testing history (aOR: 7.3, 95%CI: 1.6-32.7); positive attitude towards HCV was associated with the use of recreational substances (aOR: 3.1, 95%CI: 1.1-9.0). CONCLUSIONS: The majority of Chinese MSM showed an inadequate knowledge of and negative attitude towards HCV irrespective of HIV infection status. More tailored education campaigns and multicomponent interventions are required to be targeted on MSM, and more researches are also needed to inform how best to address the negative attitudes of this population towards HCV.

Expanding hepatitis C virus test uptake using self-testing among men who have sex with men in China: two parallel randomized controlled trials.

BACKGROUND: HCV self-testing (HCVST) may be an effective strategy to address low rates of HCV test uptake among men who have sex with men (MSM). We evaluated the effectiveness and cost of providing HCVST to increase HCV test uptake among MSM in China. METHODS: Two parallel, unmasked, individual-level randomized controlled trials were conducted. HIV-negative MSM and MSM living with HIV were enrolled from 22 cities in China. Men in both trials were randomly assigned (1:1) into standard-of-care (SOC) or HCVST arms. The primary outcome was the proportion of participants who tested for HCV during the trial period. Intervention effects were estimated using multiply imputed data in the main analysis. Costs were measured using a micro-costing approach. RESULTS: A total of 84 men who were HIV-negative (trial 1) and 84 men living with HIV were enrolled (trial 2). Overall, the proportion of individuals who underwent HCV testing during the trial period was higher in the HCVST arm compared to SOC in trial 1 (estimated risk difference (RD): 71.1%, 95% CI: 54.6 to 87.7%) and trial 2 (estimated RD: 62.9%, 95% CI: 45.7 to 80.1%). Over half (58.6%, 34/58) of HCV self-testers reported the self-test was their first HCV test. The cost per person tested in trial 1 was $654.52 for SOC and $49.83 for HCVST, and in trial 2 was $438.67 for SOC and $53.33 for HCVST. CONCLUSIONS: Compared to the standard of care, providing HCVST significantly increased the proportion of MSM testing for HCV in China, and was cheaper per person tested. TRIAL REGISTRATION: Chinese Clinical Trial Registry. REGISTRATION NUMBER: ChiCTR2100048379.

Molecular identification and functional analysis of Niemann-Pick type C2 proteins，carriers for semiochemicals and other hydrophobic compounds in the brown dog tick, Rhipicephalus linnaei.

Ticks are important vectors of many pathogens with tremendous impact on human and animal health. Studies of semiochemical interactions and mechanisms underlying chemoreception can provide important tools in tick management. Niemann-Pick type C2 (NPC2) proteins have been proposed as one type of chemoreceptor in arthropods. Here, we cloned two NPC2 genes in the brown dog tick, Rhipicephalus linnaei, the tropical lineage previously named R. sanguineus sensu lato and characterized them functionally. R.linNPC2a and R.linNPC2b genes were found to be expressed at each developmental stage with the highest level in adult males. By using quantitative real-time PCR we revealed expression in multiple tissues, including midgut, ovary, salivary glands and legs. Ligand binding analysis revealed that R.linNPC2b bound a wide spectrum of compounds, with ß-ionone, α-amylcinnamaldehyde, 2-nitrophenol and benzaldehyde displaying the strongest binding affinity (Ki < 10 µM), whereas R.linNPC2a showed a more narrow ligand binding range, with intermediate binding affinity to α-amylcinnamaldehyde and 2-nitrophenol (Ki < 20 µM). Molecular docking indicated that the amino acid residue Phe89, Leu77 and Val131 of R.linNPC2a and Phe70, Leu132 and Phe73 of R.linNPC2b could bind multiple ligands. These residues might thus play a key role in the identification of the volatiles. Our results contribute to the understanding of olfactory mechanisms of R. linnaei and can offer new pathways towards new management strategies.

Analyses of human papillomavirus, Chlamydia trachomatis, Ureaplasma urealyticum, Neisseria gonorrhoeae, and co-infections in a gynecology outpatient clinic in Haikou area, China.

BACKGROUND: The purpose of this study was to study the infection rates of Chlamydia trachomatis (CT), Ureaplasma urealyticum (UU), Neisseria gonorrhoeae (NG), and co-infections with human papillomavirus (HPV) in a hospital gynecology outpatient clinic in the Haikou region in 2021. METHODS: From January to December 2021, the Women and Children Medical Center of Hainan Province collected 2389 samples of cervical exfoliated cells and vaginal swab specimens from gynecologic outpatients. The samples were then analyzed descriptively for data, and the detection rate of each pathogen was tallied. All vaginal swabs were obtained for CT, UU, and NG DNA testing, and cervical exfoliated cells for HPV genotyping. Analyses were performed on the detection rate of each group. RESULTS: In 2389 samples, the frequencies of pathogen identification among the 2389 samples were as follows: UU (58.43%); HPV (17.29%); CT (7.99%); and NG (0.38%). HPV, CT, UU, and NG were detected in 33.33%, 22.55%, 77.45%, and 2.94% of individuals between 15 and 20 years of age, respectively. The detection rates of CT, UU, and NG were substantially greater in the HPV-positive group than the the HPV-negative group (P < 0.05). CONCLUSION: Among gynecologic outpatients at a hospital in the Haikou area, the probability of mixed infections with genital tract pathogens in HPV-positive patients was higher compared to HPV-negative patients. Reproductive tract infections are becoming more prevalent in younger people, hence adolescent sexual health education needs improvement.

Optimizing Peer Distribution of Syphilis Self-Testing Among Men Who Have Sex with Men in China: A Multi-City Pragmatic Randomized Controlled Trial.

Syphilis testing uptake is low among men who have sex with men (MSM) around the world. Syphilis self-testing (SST) may complement facility-based testing; the distribution model is yet to be explored. This study aimed to investigate the effectiveness of peer distribution of syphilis self-testing on promoting syphilis testing. We conducted a three-arm, unblinded, parallel individually randomized controlled trial among MSM in three cities in Guangdong, China. Inclusion criteria were: men who were born biologically male, aged 18 or above, have ever had sex with a man, will refer the interventions to peers, and will take the three-month follow-up survey. Enrolled indexes were randomly assigned in a 1:1:1 ratio into standard-of-care arm (SOC arm), standard SST delivery arm (S-SST arm), and a web-based referral link SST delivery arm (RL-SST arm). The primary outcome was the number of returned photograph-verified syphilis testing results per index. A total number of 300 indexes were enrolled, with 100 indexes in each arm. The number of verified syphilis tests per index conducted by alters was 0.05 in the control arm, 0.51 in the S-SST arm, and 0.31 in the RL-SST arm. The cost per alter tested was $760.60 for SOC, $83.78 for S-SST, and $93.10 for RL-SST. Minimal adverse event was reported among both indexes and alters during the study. This study showed that peer distribution of SST could improve syphilis testing uptake among MSM in China compared to facility-based testing. This approach warrants further consideration as part of expanding syphilis self-testing.

HIV testing uptake, enablers, and barriers among African migrants in China: A nationwide cross-sectional study.

Background: African migrants in China face social, structural, and cultural barriers to human immunodeficiency virus (HIV) testing with scarce information on their HIV testing behaviours. This study estimated the prevalence of HIV testing and its social and behavioural correlates to understand how to better provide HIV testing services for African migrants living in China. Methods: We conducted a national cross-sectional survey among adult African migrants who lived in China for more than one month between January 19 to February 7, 2021. The survey was disseminated online through six African community organizations and via participant referrals. We collected data on HIV testing behaviours and history of HIV testing, social, and cultural factors and applied univariate and multivariable logistic regression to identify testing correlates. Results: Among a total of 1305 participants, 72.9% (n = 951/1305) tested for HIV during their stay in China and yielded a self-reported HIV prevalence of 0.4% (n = 4/951). The most common reason for HIV testing was to comply with Chinese residence policy requirements (88.5%, n = 842/951); for not testing was "no need to be tested" (79.4%, n = 281/354). We found most African migrants have experienced low acculturation stress (54.5%, n = 750/1305), low social discrimination (65.6%, n = 856/1305), have a moderate stigma towards HIV (54.3%, n = 709/1305), and low community engagement around sexual health and HIV topics. In multivariable analysis, African migrants who were students (adjusted odds ratio (aOR) = 3.36, 95% CI = 2.40-4.71), living in student dormitories (aOR = 3.86, 95% CI = 1.51-9.84), received health services in China in past year (aOR = 1.67, 95% CI = 1.25-2.23), had lifetime sexually transmitted infections (STI) testing (aOR = 1.95, 95% CI = 1.23-3.10), had HIV testing before coming to China (aOR = 13.56, 95% CI = 9.36-19.65), and those engaged in community discussions of HIV and sexual health (aOR = 2.77, 95% CI = 1.31-5.83) were more likely to test for HIV in China. Conclusions: Despite 73% of African migrants having tested for HIV in China, there are unmet needs and barriers identified in our study, such as language barriers. Access to HIV knowledge and testing services were the most important enablers for testing, including studentship, past STI/HIV testing, and community discussion on sexual health. Culturally appropriate and community-based outreach programs to provide information on HIV and testing venues for African migrants might be helpful to promote testing uptake.

Sexual uses of drug and alcohol among men who have sex with men in China: implications for HIV prevention.

BACKGROUND: Sexual uses of alcohol and drugs are pervasive among men who have sex with men (MSM) and associated with increased risk of HIV infection. However, there are limited studies related to sexual uses of alcohol and drugs among MSM in China. This study aims to describe the pattern of alcohol use, drug use, and multi-drug use during sex among Chinese MSM and to examine the association between condomless anal intercourse, group sex, commercial sex and HIV infection. METHODS: We conducted an online cross-sectional survey in China. Characteristics on social-demographic, sexual behaviors, and sexual uses of alcohol and drugs were collected. The associations with high-risk sexual behaviors and HIV infection were analyzed with multivariable logistic regression. RESULTS: A total of 699 MSM were included in this study. About 39.5% (230/582) of men reported sexual alcohol use in the past three months and 50.8% (355/699) reported sexual drug use. Of those reporting sexual drug use, around 10.7% (38/355) reported having multi-drug use. Factors associated with both sexual uses of alcohol and drugs included: reporting more male sexual partners (alcohol: adjusted odds ratio [aOR] = 1.77; drug: aOR = 2.12), reporting condomless anal intercourse in the past three months (alcohol: aOR = 2.08; drug: aOR = 2.08), having ever engaged in group sex (alcohol: aOR = 2.04; drug: aOR = 5.22; multi-drug: aOR = 3.52) and commercial sex (alcohol: aOR = 4.43; drug: aOR = 4.22 multi-drug: aOR = 5.07). Sexual drug use was also correlated with reported HIV-positive status (drug: aOR = 2.53, 95% CI:1.31-4.90). CONCLUSION: Sexual uses of alcohol and drugs are prevalent among Chinese MSM. Interventions to reduce the sexual use of alcohol and other drugs may be warranted among MSM in China.

Prevalence of syphilis and risk factors among HIV-positive men who have sex with men in Guangdong province.

Background: HIV-positive men who have sex with men (MSM) tend to have high syphilis incidence. Our objective is to evaluate the prevalence of syphilis and determine the risk factors of syphilis among HIV-positive MSM. Methods: A cross-sectional study with convenience sampling was performed among HIV-positive MSM in six cities of Guangdong Province from June 2020 to August 2021. Participants completed a survey including social-demographic characteristics, sexual behaviors and self-reported syphilis, chlamydia, gonorrhea, herpes, human papillomavirus statuses after HIV diagnosis. Multivariate logistic regression was used to determine the factors associated with syphilis and sexually transmitted diseases (STD). Results: Among 944 HIV-positive MSM, 141 (14.9, 95% CI: 12.7-17.2%) men had syphilis and 220 (23.3, 95% CI: 20.6-26.0%) men had STD. Multivariate analysis indicated that MSM who met male sexual partners mainly through traditional meeting places (spa or bath house, sauna, foot or body massage parlor) in the last 6 months [adjusted Odds Ratio (aOR) = 2.91, 95% CI: 1.09-7.79], and who were diagnosed with herps after the HIV diagnosis (aOR = 3.79, 95% CI: 1.16-12.39) were more likely to have syphilis. In addition, MSM who met male sexual partners mainly through traditional meeting places in the last 6 month (aOR = 2.55, 95% CI: 1.01-6.42), and who had more than one male sexual partner in the last 6 months (aOR = 1.88, 95% CI: 1.17-3.02) were more likely to have STD. Conclusions: The prevalence of syphilis and other STDs is relatively high among HIV-positive MSM in southern China. Routine syphilis screening as a part of HIV monitoring among HIV-positive MSM will have important epidemiological significance for the management of infected patients, and can help reduce the spread of syphilis.

Robust association tests for quantitative traits on the X chromosome.

The genome-wide association study is an elementary tool to assess the genetic contribution to complex human traits. However, such association tests are mainly proposed for autosomes, and less attention has been given to methods for identifying loci on the X chromosome due to their distinct biological features. In addition, the existing association tests for quantitative traits on the X chromosome either fail to incorporate the information of males or only detect variance heterogeneity. Therefore, we propose four novel methods, which are denoted as QXcat, QZmax, QMVXcat and QMVZmax. When using these methods, it is assumed that the risk alleles for females and males are the same and that the locus being studied satisfies the generalized genetic model for females. The first two methods are based on comparing the means of the trait value across different genotypes, while the latter two methods test for the difference of both means and variances. All four methods effectively incorporate the information of X chromosome inactivation. Simulation studies demonstrate that the proposed methods control the type I error rates well. Under the simulated scenarios, the proposed methods are generally more powerful than the existing methods. We also apply our proposed methods to data from the Minnesota Center for Twin and Family Research and find 10 single nucleotide polymorphisms that are statistically significantly associated with at least two traits at the significance level of 1 × 10-3.

A maintenance activity scheduling with time-and-position dependent deteriorating effects.

We deal with a single-machine scheduling problem with an optional maintenance activity (denoted by $ ma $), where the actual processing time of a job is a function of its starting time and position. The optional $ ma $ means that the machine will perform a $ ma $, after $ ma $ is completed, the machine will return to the initial state. The objective is to determine an optimal job sequence and the location of the maintenance activity such that makespan is to be minimized. Based on some properties of an optimal sequence, we introduce a polynomial time algorithm to solve the problem, and the time complexity is $ O({n}^4) $, where $ {n} $ is the number of jobs.

Correction: Expanding syphilis test uptake using rapid dual self-testing for syphilis and HIV among men who have sex with men in China: A multiarm randomized controlled trial.

[This corrects the article DOI: 10.1371/journal.pmed.1003930.].