Transmission of non-A, non-B hepatitis by heat-treated factor VIII concentrate.

In-vitro and animal studies have shown that viral agents can be removed from or inactivated in clotting factor concentrates by physical or chemical treatment. However, clinical data have as yet not substantiated the results of these studies. 13 haemophilia A patients who had not been treated previously with blood or blood products were given a dry-heated factor VIII concentrate and were tested serologically over the next 12 months. Hepatitis developed in 11 patients (84%) and was invariably of type non-A, non-B. Morbidity was not related to the lot of the therapeutic material or to the number of infusions. The incubation period was either 5 or 8-11 weeks, and only 1 patient had symptoms. Aminotransferase elevation showed both monophasic and biphasic patterns. During the follow-up period signs of the disease disappeared in 10 patients (90%). These findings contrast with the absence of non-A, non-B hepatitis in chimpanzees given the same heated concentrate. Thus, clinical studies in first-exposure haemophiliacs are essential for the true evaluation of the safety of new "treated" concentrates.