A multicentric seroepidemiological survey of HTLV-I/II in Italy

Several studies carried out in the USA and in Europe have shown the presence of HTLV-I/II antibodies in subjects belonging to high-risk groups for HIV infection as well as blood donors. Concern about the presence of HTLV-I/II markers in the normal population, as well as the efficient transmission of HTLV-I/II by whole blood or infected blood cells have led several countries to include screening for anti-HTLV-I/II among the mandatory serological testing of blood donors.

In order to assess the risk of HTLV-I/II infection related to blood transfusions, a multicentric survey for antibodies against HTLV-I and HTLV-II was carried out involving 10 Italian sites during the spring of 1991.

Serum specimens were collected from 14,598 blood donors, 1,411 injecting drug users, 1,015 thalassemics, 142 hemophiliacs and 138 hemodialysis patients. HTLV antibodies were detected by a screening EIA which combines a viral lysate with a recombinant HTLV-I env protein (p21e). The serological confirmation was performed by a semi-automated dot-blot immunoassay that detects gag p19 and p24 and env p21e specific antibodies, while the discrimination of HTLV-I and HTLV-II reactivities was carried out by EIAs employing synthetic peptides of the ENV region specific for each virus.

The seroprevalence of confirmed positives was 0.034% among blood donors and 3.61% among IDUs, while no sample of the other categories could be confirmed, although several were indeterminate and one thalassemic reacted against HTLV-I on peptide testing. HTLV-I reactivity was observed in one blood donor, while all 38 of the 51 confirmed seropositive IDU's reacted only to the HTLV-II synthetic peptide.

These data confirm a high prevalence of HTLV-II among Italian IDUs and show an HTLV-I/II seroprevalence among blood donors very similar to that which was found in the USA volunteer blood donors. A surveillance program among blood donors seems advisable in order to establish the possible need of a mandatory screening for HTLV-I/II.