The resurgence of syphilis among pregnant women in southern Chile

Background: National rates of HIV, gonorrhoeae and syphilis have increased in Chile in recent years, but it is not known if syphilis among pregnant women (PW) is also escalating. Aim: To explore syphilis rates among PW in a southern Chilean region and to describe clinical features of mothers and offspring. Patients and Methods: We selected PW with positive VDRL or T. pallidum micro-hemagglutination (MHA-TP) reactive tests, referred to a high-risk obstetrical pathology center between 2011 and 2019. Clinical information of mothers and their offspring was obtained from their medical records. Results: Syphilis rates among PW increased from a4 to 7.2 per 1,000 live births in the reference center from 2013 to 2019, along with a national and regional increase in both sexes. Twenty-nine cases of PW with syphilis were identified with a median age of 28 years (interquartile range 23-32). Seventeen percent had a history of drug abuse, and 14% had previous sexually transmitted diseases. In seven cases (24%), the diagnosis occurred at delivery. Three percent of patients had a primary syphilis, 14% a secondary syphilis, 24% an early latent syphilis, and 59% a latent syphilis. All cases except one case were treated with benzathine penicillin G and the remaining with erythromycin due to allergy suspicion. Penicillin desensitization was required in two cases (7%). Treatment timing was inadequate in 10 cases (34.5%). Of 19 patients with available serological follow-up, 10 (53%) showed a significant decrease in VDRL titers (>= 2 dilutions) and two cases had re-infection. Two patients (7%) had an abortion, two had congenital syphilis (7%), and six had premature births (21%), totaling 35% of adverse-pregnancy outcomes. Conclusions: Resurgence of syphilis among pregnant women is happening in southern Chile and is associated to adverse-pregnancy outcomes.