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

Human immune deficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) and syphilis are the most common sexually transmitted diseases (STDs) worldwide, as well as in China. The objective of this study is to describe the trend of spatial and temporal variation of HIV/AIDS and syphilis in mainland China from 2007 to 2017. Stratified analysis was conducted according to age and the GDP per capita. Estimated Annual Percentage Change (EAPC) was calculated and spatial autocorrelation analysis was used to evaluate the epidemiology and identify clusters. The morbidity of new HIV infection increased from 2.5034/100 000 in 2007 to 6.9247/100 000 in 2017, with an EAPC of 9.84 (95% confidence interval [CI]: 9.07-10.60). From 2007 to 2017, the morbidity of syphilis presented a significant upward trend from 15.8834/100 000 to 34.4867/100 000 (EAPC = 6.48, 95% CI: 4.23-8.73). The number of new HIV infections (205 084) and syphilis (921 279) were highest in the 20-30 years old group, where the incidence decreased with age over 20 years. In general, HIV and syphilis infection had the same incidence trend according to age and time stratification. The morbidity of new HIV infection was mainly reported from Xinjiang and southwestern China. As for syphilis, the highest was found in Zhejiang in Xinjiang and southeast coastal areas. Both HIV and syphilis infection showed a nonrandom positive correlation by Moran's I value. The High-High cluster areas of HIV infection were concentrated in southwestern and eastern China due to syphilis. A highly significant positive correlation was found between gross domestic product per capita and syphilis infection (p < 0.05) but was not associated with HIV infection. The incidence of AIDS/HIV and syphilis is increasing year by year, and a higher prevalence is found in younger individuals. More attention should be paid to HIV infection in the southwest, syphilis in southeast coastal areas, and both the two diseases in Xinjiang.