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Biological false reactive VDRL tests: when to re-test?
1Department of Laboratory Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. wviroj@pioeer.netserv.chula.ac.th
The Southeast Asian Journal of Tropical Medicine and Public Health
|September 16, 2003
Summary
Biological false reactive syphilis screening tests, confirmed by TPHA negative results, typically resolve within 10 weeks. Repeat syphilis serology testing is recommended 10 weeks after an initial false reactive VDRL test.
Area of Science:
- Clinical Medicine
- Infectious Diseases
- Public Health
Background:
- Syphilis serology is a critical screening test for international migrant workers.
- Reactive syphilis serology results often lead to rejection of migrant workers by destination countries.
- Biological false reactive results necessitate further investigation and repeat testing.
Purpose of the Study:
- To prospectively evaluate the seroconversion timeline for biological false reactive VDRL tests.
- To establish an evidence-based recommendation for repeat syphilis serology testing intervals.
Main Methods:
- Prospective study of 30 patients with biological false reactive VDRL tests (TPHA negative).
- Syphilis serology testing performed every two weeks for all participants.
- Analysis of seroconversion rates and time to VDRL non-reactivity.
Main Results:
- The expected range for seroconversion was 9.25 to 10.49 weeks.
- 25 out of 30 patients returned to VDRL non-reactive status within 10 weeks.
- Three patients resolved within 6 weeks, and two within 14 weeks.
Conclusions:
- Biological false reactive VDRL tests generally resolve within a predictable timeframe.
- Repeat syphilis serology testing 10 weeks post-initial false reactive result is recommended.
- This guideline aids in managing migrant worker screening and preventing unnecessary rejections.