Rapid development and urbanization can increase ambient exposure to NO2 and its health risks in individuals. However, the association between NO2 exposure and outpatient visits of patients with psoriasis has rarely been reported, though psoriasis is a major skin disease in rapidly urbanizing areas with high population densities. This study applied a time-stratified case-crossover design to investigate the effect of short-term exposure to ambient NO2 on outpatient visits for psoriasis from 2014 to 2020 in Guangzhou, China (n = 62,305). A subgroup analysis was performed to evaluate NO2 impacts on vulnerable subpopulations. Our results showed that the NO2 concentration during the study period was lower than that of the level II threshold from China (PRC) but higher than that set by the WHO, indicating moderate air quality. However, a 10-µg m -3 increase in NO2 concentration could still be associated with 3.1% higher outpatient visits for psoriasis (adjusted RR of lag 0 d:1.031 [CI:1.025, 1.037]). NO2 exposure can also pose long-term risks. Additionally, NO2 impacts on psoriasis may be independent of other pollutants.

Background Syphilis is a common sexually transmitted infection (STI) among men who have sex with men (MSM). Increasing syphilis testing is important to syphilis control. However, in low- and middle-income countries like China, syphilis testing rates remain low among MSM. We describe a randomized controlled trial protocol to examine the effectiveness of social network distribution approaches of syphilis self-testing among MSM in China. Methods We will recruit index and alter MSM. Indexes will be eligible if they: are born biologically male; aged 18 years or above; ever had sex with another man; are willing to distribute syphilis testing packages or referral links to their alters; and willing to provide personal contact information for future follow-up. Three hundred MSM will be recruited and randomly assigned in a 1:1:1 ratio into three arms: standard of care (control arm); standard syphilis self-testing (SST) delivery arm; and referral link SST delivery arm. Indexes will distribute SST packages or referral links to encourage alters to receive syphilis testing. All indexes will complete a baseline survey and a 3-month follow-up survey. Syphilis self-test results will be determined by photo verification via a digital platform. The primary outcome is the mean number of alters who returned verified syphilis testing results per index in each arm. Discussion The trial findings will provide practical implications in strengthening syphilis self-testing distribution and increasing syphilis testing uptake among MSM in China. This study also empowers MSM community in expanding syphilis testing by using their own social network. Trial registration Chinese Clinical Trial Registry, ChiCTR2000036988. Registered 26 August 2020 - Retrospectively registered.

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 female sex workers were recruited 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 sought commercial sex online, 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 accidental 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 in China engage 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.

Background Syphilis is a common sexually transmitted infection (STI) among men who have sex with men (MSM). Increasing syphilis testing is important to syphilis control. However, in low- and middle-income countries like China, syphilis testing rates remain low among MSM. We describe a randomized controlled trial protocol to examine the effectiveness of social network distribution approaches of syphilis self-testing among MSM in China. Methods We will recruit index and alter MSM. Indexes will be eligible if they: are born biologically male; aged 18 years or above; ever had sex with another man; are willing to distribute syphilis testing packages or referral links to their alters; and willing to provide personal contact information for future follow-up. Three hundred MSM will be recruited and randomly assigned in a 1:1:1 ratio into three arms: standard of care (control arm); standard syphilis self-testing (SST) delivery arm; and referral link SST delivery arm. Indexes will distribute SST packages or referral links to encourage alters to receive syphilis testing. All indexes will complete a baseline survey and a 3-month follow-up survey. Syphilis self-test results will be determined by photo verification via a digital platform. The primary outcome is the mean number of alters who returned verified syphilis testing results per index in each arm. Discussion The trial findings will provide practical implications in strengthening syphilis self-testing distribution and increasing syphilis testing uptake among MSM in China. This study also empowers MSM community in expanding syphilis testing by using their own social network. Trial registration: Chinese Clinical Trial Registry, ChiCTR2000036988. Registered on 26 August 2020