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

Abstract

ObjectiveThis study investigated the association between syphilis seroprevalence and age among blood donors, and described the distribution of serological titres among syphilis-infected donors, aiming to confirm the syphilis epidemic characteristics and to promote effective interventions for older adults.MethodsData were obtained from the Shenzhen Programme for Syphilis Prevention and Control in 2014–2017. Blood samples were screened using the ELISAs, and confirmed using the Treponema pallidum particle agglutination assay (TPPA) and toluidine red unheated serum test (TRUST).ResultsAmong 394 792 blood donors, 733 tested TPPA and TRUST positive (active infection), and 728 tested only TPPA positive (historical infection). The overall prevalence of syphilis seropositivity was 370.1 per 100 000 (95% CI 351.1 to 389.0 per 100 000); the prevalence of active infection was 185.7 per 100 000 (95% CI 172.2 to 199.1 per 100 000). People aged ≥45 years displayed a prevalence of 621.8 per 100 000 in syphilis seropositivity and 280.5 per 100 000 in active infection, which were 3.8 times and 2.4 times higher than that for people aged <25 years, respectively. The prevalence of syphilis seropositivity (χ2 trend=311.9, p trend<0.001) and active infection (χ2 trend=72.1, p trend<0.001) increased significantly with age. After stratification by gender and year of donation, the increasing trend of prevalence with age remained (p trend<0.05), except for the prevalence of active infection in males and females in 2014. About 16.3% of donors with active infection and aged ≥45 years had a TRUST titre of ≥1∶8, lower than that of patients aged <25 years (51.3%) and 25–34 years (34.1%).ConclusionsThe findings confirm the high prevalence of syphilis among older adults, and suggest the need to increase awareness among healthcare providers and deliver more targeted prevention interventions for older adults to promote early testing.

Prevalence of Syphilis Infections Among Volunteer Blood Donors in Jinan Blood Center, China: A 15-Year Retrospective Study

“…33 Some previous studies found that females were more likely to be affected by STDs partly because of the different physiology and anatomy of the genital organs between both sexes. 34 Studies have proved that the male-to-female transmission rate was higher than the female-to-male rate in certain STDs, such as HIV. 34 , 35 A study among volunteer blood donors in Chengdu, China, reported that shared razors, ear piercings, and tattoos were also the high-risk factors for syphilis infection.…”

“… 34 Studies have proved that the male-to-female transmission rate was higher than the female-to-male rate in certain STDs, such as HIV. 34 , 35 A study among volunteer blood donors in Chengdu, China, reported that shared razors, ear piercings, and tattoos were also the high-risk factors for syphilis infection. 36 They speculated that sharing cosmetic instruments may be a high-risk factor.…”

Infectious diseases among elderly persons: Results from a population-based observational study in Shandong province, China, 2013-2017

“…Our results were in agreement with the passive surveillance reported by China Information System for Disease Control and Prevention (CISDCP) [ 30 ]. Similarly, serological studies of syphilis in other regions of China reported high prevalence of syphilis among the elderly [ 31 ]. The possible reasons may be due to the longer life expectancy, more common unsafe sex, infrequent use of condoms, and more medical screening.…”

Epidemiology, Management, Quality of Testing and Cost of Syphilis in Germany: A Retrospective Model Analysis

“…The unusually high number of syphilis cases among the older female insurance population could have several reasons: it could be an artifact within the dataset, or the age group might consist of a bigger proportion of women at a higher risk of being infected with syphilis, or it could be a remnant of the surviving World War II generation. Since Treponema pallidum -specific antibodies show a lifelong persistence regardless of treatment status ( 30 ), a rising seroprevalence of Treponema pallidum -specific antibodies is not uncommon in aging populations ( 31 – 33 ).…”