The Distribution of Syphilis Among Inpatients in Wenzhou, China: A Hospital Based Study

The high prevalence of syphilis among inpatients is an important concern in clinical settings. Thus, a better understanding of the serological test would be valuable. We analyzed the serological test results for syphilis among the inpatients in Wenzhou central hospital, China, to estimate the distribution of syphilis this Chinese population. The blood samples of 81946 inpatients at the hospital from January 2010 to December 2012 were collected and retrospectively analyzed. Syphilis testing was conducted using a Treponema pallidum enzyme-linked immunosorbent assay (TP-ELISA) and a TP particle agglutination (TPPA) assay. A toluidine red unheated serum test (TRUST) was then used to determine the titer of TP antibody in the TP- ELISA-positive samples. In total, 1618 of the 81946 inpatients showed positive syphilis serology; the positive rates in 2010, 2011, and 2012 were 2.27%, 1.58%, and 2.11%, respectively. Males had a significantly higher positive rate when compared to females. Surprisingly, the highest positive rate was observed among patients older than 80 years, followed by patients younger than 19 years, while patients aged 20 - 39 years had the lowest positive rate. The TRUST titer of most TP-positive cases was less than 1:8. Patients aged 20 - 39 years showed the highest percentage of TRUST titer values ≥ 1:8, while patients older than 80 years showed the lowest percentage; the differences between these two groups were statistically significant. The serological characteristics of syphilis varied with gender and age. Syphilis screening and control should be conducted for young patients and pregnant women, but special attention should also be paid to elderly inpatients. The TRUST assay is better used in syphilis screening and for judgment of curative effects, but the diagnosis needs specific methods, such as the TP-ELISA and the TPPA test.