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The International Standard for Human Syphilitic Serum
Bulletin of the World Health Organization
|July 7, 2010
Summary
A new international standard for human syphilitic serum was established by the WHO to improve syphilis serological test accuracy. This standard allows global laboratories to calibrate their tests, enhancing result comparability worldwide.
Area of Science:
- Immunology
- Microbiology
- Public Health
Background:
- The World Health Organization (WHO) previously established reference preparations for cardiolipin and egg lecithin.
- These preparations facilitate the reproduction of cardiolipin antigens for syphilis serological testing.
Purpose of the Study:
- To establish an international standard preparation for freeze-dried human syphilitic serum.
- To improve the comparability of syphilis serological test results globally.
Main Methods:
- Collaborative studies involving multiple international laboratories.
- Establishment of the International Standard for Human Syphilitic Serum by the WHO Expert Committee on Biological Standardization in 1957.
- Detailed technical analysis of investigations and collaborative assay data.
Main Results:
- The International Standard for Human Syphilitic Serum is now available from the International Laboratory for Biological Standards.
- One International Unit (IU) of Human Syphilitic Serum equals 3.617 mg of the freeze-dried standard.
- A reconstituted solution of 8 IU/ml can be prepared.
Conclusions:
- The new standard enables major serological laboratories to calibrate national reference sera.
- Improved comparability of syphilis testing results across different regions is anticipated.
- The standard provides a basis for consistent and reliable syphilis diagnosis.

