Detection of Rare Cases of HTLV-I and -II Infections and High Numbers of HTLV-Seroindeterminate Results in Bavarian Blood Donors

Abstract

Background: In order to evaluate the prevalence of human T-cell lymphotropic virus type I and II (HTLV-I/-II) infections in Germany, the Bavarian blood donor population was screened. Material and Methods:Between 1991 and 1994 around 1.5 million donations from about 375,000 blood donors of the Bavarian Red Cross (BRK) were tested for HTLV-I/-II in an antibody screening test. Sera repeatedly reactive in the screening test at the BRK blood bank were further assayed in additional enzyme-linked immunosorbent assays (ELISA), Western blot (WB) and radioimmunoprecipitation assay (RIPA). Selected donors were analyzed by polymerase chain reaction (PCR). Results:Only 4 HTLV-I/-II infections could be confirmed by WB and by RIPA, indicating a seroprevalence of 0.001%. Three positive donors were American soldiers and the fourth one was a German woman. Out of 609 sera reactive in at least two antibody screening tests, only 4 could be confirmed in WB as HTLV-I or -II positive. However, reactivity of these sera appears not to be related to an HTLV-I or -II infection, as shown by selected samples testing negative by RIPA and PCR. Conclusions:HTLV-I/-II seroprevalence in Bavarian blood donors is very low which implies that a general testing of all blood donations should not be recommended. However, donors with sexual partners from HTLV-endemic regions should be tested. Concerning serological diagnosis, we would suggest to modify the WHO-based interpretation criteria in countries with low HTLV prevalences: Only sera with antibodies to 1 or 2 Gag andthe 2 recombinant Env proteins should be considered HTLV positive.