AIDS and haemophilia.

Approximately 1% of all AIDS cases are haemophiliacs. LAV/HTLV-III is transmitted by blood and in factor VIII concentrates. Since 1981, increasing numbers of haemophiliacs have been infected, as indicated by detection of antibodies to LAV/HTLV-III. Up to 90% of haemophiliacs in some populations are now seropositive, but to date less than 1% have progressed to clinical AIDS. Immunological abnormalities, in particular reduced T-lymphocyte helper/suppressor ratios, are common in haemophiliacs treated with factor VIII. Such abnormalities do not necessarily indicate past infection by the AIDS virus, but they may predispose to infection following exposure to the virus. Blood Transfusion agencies are introducing screening tests for antibodies to LAV/HTLV-III to help prevent the spread of AIDS by blood products. Heat treated factor VIII concentrate is now available and appears not to transmit AIDS. Factor IX concentrate may also transmit LAV/HTLV-III, but less frequently. A few cases of AIDS have occurred in Haemophilia B (Christmas Disease) patients.