Reduced risk of non-A, non-B hepatitis after a first exposure to 'wet heated' factor VIII concentrate.

The risk of post-infusion non-A, non-B hepatitis (NANBH) in patients receiving a first exposure to unheated or conventionally 'dry heated' factor VIII concentrates approaches 100%, implying invariable contamination of these products. Amongst 18 patients who received a first treatment with a 'wet heated' commercial concentrate, five (28%) developed asymptomatic NANBH, suggesting a more efficient inactivation of NANB agent(s) by this process. 2/9 (22%) of the batches of concentrate used in the study were implicated in NANBH transmission. One of those two batches, responsible for NANBH in four patients, had been prepared from a plasma pool containing an unusually large proportion of donations with high alanine aminotransferase (ALT) levels. A resulting high level of viral contamination in this batch may have been sufficient to override the effects of the sterilization process. All patients remained anti-HIV seronegative at 17-28 months of follow-up.