Syphilis Testing Algorithms Used in Laboratories in Latin America and the Caribean

Background: 

Accurate syphilis testing is critical in achieving the Americas Region goal of eliminating mother-to-child transmission of HIV and congenital syphilis.  Little is known about syphilis testing in Latin America and Caribbean countries.

Methods: 

In 2014, the Pan American Health Organization asked 35 member states to complete a survey on syphilis tests, testing algorithms, quality assurance strategies and challenges faced.  Directors or managers of national and regional reference laboratories and large local hospitals (public and private) were invited to respond using an electronically administered survey accessed via online web link.

Results: 

Of 69 participating laboratories representing 30 countries (86% of eligible), 52% were reference laboratories and 94% were public. The most common syphilis algorithm, reported by 33 (48%), was screening with a non-treponemal test (NTT) with reactive tests confirmed by a laboratory-based treponemal test (TT). Nine (13%) more laboratories reported NTT screening with all tests confirmed by a laboratory-based TT; 9 others reported NTT screening with reactive tests confirmed using a rapid syphilis (treponemal) test (RST).  Six (9%) screened with laboratory-based TTs and confirmed with a NTT.  Fourteen laboratories (20%) used only one test. Of 28 (41%) laboratories reporting use of RSTs, only 4 reported RSTs were used in clinical (vs. laboratory) settings. Two thirds (67%) of laboratories participated in an annual external quality assurance program, 34 (49%) conducted routine on-site observations of testing, and 28 (41%) employed proficiency testing strategies.  Reported challenges included frequent stock outs, inability to procure reagents and equipment, and limited opportunities to train staff.

Conclusions: 

Most surveyed laboratories used both screening and confirmatory testing for syphilis testing, predominantly with a traditional approach. Few countries had adopted RSTs in antenatal clinical settings, although this could improve screening and treatment coverage in pregnant women. Many laboratories face challenges in ensuring adequate supplies and trained personnel.