Introduction:
Syphilis is an infectious disease caused by Treponema pallidum(TP), a member of the Spirochaetaceae family. It is one of the most
common sexually transmitted diseases. According to the World Health
Organization (WHO) estimates, approximately 17.7 million people all over
the world between the ages of 15 and 49 years had syphilis in the year
2012, and this number reportedly increases by an estimated 5.6 million
every year (1). The estimated prevalence and incidence of syphilis
varies with region and country. The highest prevalence of syphilis has
been reported in Africa, with more than 60% of new cases occur in
developing countries (1). Gestational syphilis reportedly occurs most
frequently in Africa, accounting for more than 60% of the global
estimates (2). Syphilis is a Category 5 infectious disease in Japan
according to the Infectious Diseases Law, and the number of syphilis
cases has been gradually increasing since 2013 (3). Syphilis, especially
among young people, has become a concern in the recent years. Syphilis
in pregnant women and congenital syphilis have become public health
issues worldwide (4). In Japan, the haematology test for syphilis is
performed at public expense as a screening test in the first trimester
of pregnancy during antenatal health examination. In some foreign
countries, syphilis screening tests are also conducted in the second and
third trimesters of pregnancy (5). However, in Japan, screening tests
for syphilis are not conducted after the initial examination.
Herein, we report a case in which a vulvar ulcer at 37 weeks of
gestation led to the diagnosis of syphilis after a negative screening
test during early pregnancy.