Association between syphilis seroprevalence and age among blood donors in Southern China: an observational study from 2014 to 2017

Wu, Xiaobing; Guan, Yang; Ye, Jianbin; Fu, Hanlin; Zhang, Chunlai; Lan, Lina; Wu, Fengxin; Tang, Fen; Wang, Feng; Cai, Yumao; Yu, Weiye; Feng, Tiejian

The global population is ageing as a combined result of the demographic transition from high to low levels of fertility and mortality. 1 Population ageing increases the total global disease burden, with approximately 23% attributable to disorders in people aged ≥60 years. 2 Chronic non-communicable diseases, including cardiovascular disease, malignant neoplasms, and chronic respiratory diseases, are the leading contributors to disease burden in older people. 2 However, infectious diseases also considerably affect older people, as an increasing incidence of infectious diseases, such as human immunodeficiency virus (HIV) and syphilis, was shown from recent surveillance data. [3] [4] [5] This large disease burden among older people calls for improvements in the healthcare system and more investments and programs focusing on healthy ageing. 2 Syphilis, caused by Treponema pallidum, is a chronic infection with diverse clinical manifestations occurring in distinct stages, and may lead to blindness, dementia, delirium, death, etc., if not treated immediately or adequately. 6 Syphilis can also aid the passage for HIV to invade, reduce the CD4 T-cell levels, and increase the viral load, thereby aggravating the harm caused by HIV. 7 Even though syphilis can be effectively treated with penicillin, about 36.4 million new cases occur annually. 8 In China, the syphilis epidemic has rapidly increased, with a 16.3% increase per year during the first decade after the severe acute respiratory syndrome (SARS) outbreak. 9 The reported incidence was slightly higher among females than males (ratio, 1.00 to 0.92), but it varied significantly with age. 5 Younger people (aged 20-39 years) reported the highest syphilis incidence and accounted for the largest proportion of newly reported cases; however, the older age groups (aged ≥45 years) had the fastest growth in incidence, and males aged ≥60 years displayed a peak incidence of latent syphilis in the last decade. 5 With the accelerated ageing of the global population, the increasing syphilis epidemic among older adults is alarming.