Seroepidemiology of the human T-cell leukaemia/lymphoma viruses in Europe: The HTLV European Research Network

An extensive collaboration of laboratories and investigators has been developed to define the seroprevalence of human T-cell leukaemia/lymphoma virus type I and II (HTLV-I and -II) infection in Europe. An algorithm for serological screening for HTLV-I and -II infection has been established by consensus. Data from screening almost 4 million subjects, including many unpublished studies, which conform to this algorithm are presented. In extensive studies the seroprevalence of HTLV-I/II in blood donors is low, ranging from <1 in 100,000 to 30 in 100,000 donors and is due predominantly to HTLV-I. In antenatal clinics in France and the United Kingdom the seroprevalence of HTLV-I is >0.2% but surveillance in this setting has been limited and extensive study of the seroprevalence of HTLV-I/II infection in pregnant women in Europe is urgently required to determine the need for HTLV- I/II antenatal screening. HTLV-I is present in populations who have immigrated to Europe from endemic areas and is spreading into indigenous European populations, particularly through sexual transmission to females. HTLV-II infection is present predominantly amongst IVDU and is usually a coinfection with HIV-1. There are considerable regional differences in HTLV- II seroprevalence.