Seroepidemiology of HTLV-I/II in universal screening of blood donations in France.

OBJECTIVE

To evaluate the serological and epidemiological characteristics of HTLV-I/II-positive blood donors in continental France during the first 6 months of universal screening of blood donations (n = 1,816,927).

METHOD

A collaborative investigation of all confirmed anti-HTLV-I/II-positive samples reported by blood transfusion centres was performed. Seventy-three out of 77 reported samples were retested at two reference laboratories. Epidemiological data on risk factors were compiled.

RESULTS

Of the 73 retested samples, 66 were confirmed to be HTLV-I-positive and one to be HTLV-II-positive; six samples were designated false-positive, mainly because of non-specific reactivity to recombinant gp21 in Western blot. The overall prevalence of HTLV-I/II in continental France is 0.039 per thousand. The main risk factor identified for HTLV-I infection was directly (origin) or indirectly (heterosexual contact) linked to endemicity in the Caribbean. The cost per case of avoided contamination in the 6-month period of this study was 1.36 million French francs.

CONCLUSIONS

Sixty-two per cent of HTLV-I/II-infected blood donations would not have been discarded through the previous targeted HTLV screening or through other mandatory tests, including anti-hepatitis B core. To avoid false-positive results, we propose a new algorithm of diagnosis.