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AABB > Press Room > Statements

Statement Before BPAC on Syphilis Testing – 9/14/00 


September 15, 2000

Syphilis Testing

Presented by Louis Katz, MD
Chair, AABB Transfusion Transmitted Disease Committee

The American Association of Blood Banks (AABB) is the professional society for over 9,000 individuals involved in blood banking and transfusion medicine and represents roughly 2,200 institutional members, including community and Red Cross blood collection centers, hospital based blood banks, and transfusion services as they collect, process, distribute, and transfuse blood and blood components and hematopoietic stem cells. Our members are responsible for virtually all of the blood collected and more than 80 percent of the blood transfused in this country. For over 50 years, the AABB's highest priority has been to maintain and enhance the safety and availability of the nation's blood supply.

The AABB appreciates this opportunity to provide comment to the Blood Products Advisory Committee (BPAC).

The serologic test for syphilis (STS) has been retained in the United States for two ends: prevention of transfusion transmitted syphilis and as a surrogate for risk behaviors associated with HIV infection.

Transfusion- transmitted syphilis has not been recognized in the United States in more than 30 years. In fact, in 1985 an FDA committee recommended elimination of STS for blood donors. This recommendation was not implemented when the issue of the STS’s value as an HIV surrogate was raised.

The reasons for the disappearance of transfusion syphilis are multiple, including the declining incidence of infectious syphilis in this country and donor deferral policies reducing the presentation of those at risk for infectious syphilis. Storage of red blood cells at refrigerator temperatures and improved oxygen tension in stored platelets are probably important contributing factors. Still there is transfusion of fresh red cell components, and platelets are stored at room temperature. Receipt of antimicrobial therapy by those ill enough to require transfusion support may also be important in preventing either infection or the recognition of transfusion syphilis. From a biological standpoint, it must be emphasized that the spirochetemia associated with transfusion transmissibility of T. pallidum generally occurs before the STS is reactive and spirochetemic donations are being transfused as we speak.

At the NIH Consensus Development Conference in January 1995, it was concluded that … “current blood storage conditions would not appear to provide an adequate margin of safety against transfusion-transmitted syphilis, should the donor screening test be eliminated. Further information concerning T. pallidum survival under blood and platelet storage conditions, and the application of molecular techniques to assess the presence of T. pallidum DNA in serologically positive units, would allow better assessment of this question.” Data presented at the AABB Annual Meeting in 1999 address this recommendation. Orton et.al. have presented this committee their data on PK-TP positive, FTA-ABS confirmed donors using two PCR methods, and found none with detectable DNA. On the other hand, the CDC data demonstrate spirochetemia by sensitive DNA tests.

Regarding the value of the STS as a surrogate for other TTDs, even prior to the implementation of sensitive NAT assays for HIV and HCV, the Consensus Development Conference concluded

“…cross-sectional studies and examination of prior donations from donors undergoing HIV seroconversion indicate that serologic tests for syphilis have very little value as surrogate markers for HIV infection in recently infected persons who have not yet developed detectable antibodies to HIV. Syphilis testing is likely to identify less than one such donor annually within the United States. This low efficacy of syphilis testing as a surrogate marker of HIV is not sufficient by itself to warrant its application to all blood donors. Low positive predictive values for HBV, HCV, or HTLV infections similarly do not support retention of syphilis testing as a surrogate for these infections”.

We are aware of CDC data suggesting there are early syphilis cases being reported among blood and plasma donors. Unfortunately, as the CDC investigators admit, they are unable to segregate paid plasma donors from volunteer whole blood donors in their data, which we view as a serious flaw. Taken against the background of historically low infectious syphilis rates in this country and the failure of clinicians to recognize even isolated cases of transfusion associated syphilis, we question the applicability of the CDC data to the volunteer whole blood donor sector.

Ramsey and Sherman reviewed FDA reported blood component recalls in the US from 1990 through 1997. Of an estimated 241,800 components recalled, 57% (137,100) were for incorrect syphilis testing. These were primarily in a single large recall of units where weakly reactive STS results might have been called negative. This recall was classified, by FDA, as a class III recall, “not likely to cause adverse health consequences”.

With these points in mind, AABB believes the requirement for performing an STS on each whole blood donation can safely be eliminated based on thirty years experience. However, we understand the FDA concerns and would support further studies if the FDA is not willing to endorse discontinuation at this time.

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