HTLV-III seropositivity in European haemophiliacs exposed to Factor VIII concentrate imported from the USA.

77 Scottish haemophiliacs and 22 Danish haemophiliacs were serologically tested for antibodies to human T-cell leukaemia virus III (HTLV-III). Since 1979 the Scottish patients had been treated largely with factor VIII concentrate produced in Scotland, whereas all but 2 of the Danish patients had received both locally prepared concentrate and commercial concentrate made from US donor material. 15.6% of Scottish and 59.1% of Danish haemophiliacs were antibody positive (p less than 0.001). None of 11 haemophiliacs not treated in the period 1979-84 was seropositive. 2 (6.7%) of 30 subjects who had been treated with locally produced concentrate only were antibody positive, compared with 23 (39.7%) of 58 subjects who had been treated with commercial concentrate. Among 52 users of both commercially and locally produced factor VIII concentrate, seropositivity was directly correlated with the consumption of commercial concentrate (p less than 0.001) but not locally produced material. These data indicate that European haemophiliacs were exposed to HTLV-III via some factor VIII concentrates obtained from the USA.