Reduction in routine confirmation with Treponema pallidum particle agglutination (TPPA) for new syphilis cases detected by serology
CADHAM PROVINCIAL LABORATORY
Beginning January 1, 2025, new cases of syphilis detected by Cadham Provincial Laboratory (CPL) using serologic techniques will no longer be routinely confirmed by Treponema pallidum particle agglutination (TPPA).
All syphilis serologic investigation tends to begin with the CMIA syphilis screen test. As a rule, syphilis cases (beyond the early incubation period) will be positive by CMIA syphilis screen test. All screen test positive individuals will then have syphilis titres checked using the Rapid Plasma Reagin (RPR) test. Most new cases of syphilis have mid- to high RPR titres, and in the past have uniformly confirmed using TPPA. TPPA confirmation will no longer routinely be performed on these types of specimens.
TPPA confirmation will continue to be routinely be performed in the following circumstances:
- CMIA screen positive but RPR negative specimens
- Borderline CMIA positive specimens, regardless of RPR titre
Retrospective studies of recent CPL syphilis serology indicates that these scenarios benefit the most with the addition of TPPA confirmation.
In general terms, there should be little to no impact to clinicians or public health practitioners with this change. If you feel you have a case that requires further investigation with TPPA, please contact CPL or the CPL physician on-call to discuss.
References/Resources:
Please refer to the CPL Guide to Services (G2S) for collection and submission information.
More Information:
CPL G2S website
Manitoba Syphilis Protocol
Contact Information:
Paul Van Caeseele, MD
Medical Director, Cadham Provincial Laboratory | Shared Health
204-945-6456 or email
Submitted by: Loreley Fehr, Manager, Health Services – Public Health-Healthy Living