'How frequent is posttranfusion hepatitis after the introduction of 3rd generation donor screening for hepatitis B? What is its probable nature?

Third generation donor screening for hepatitis B is not generally efficacious in reducing PTH B except under certain epidemiological conditions. The nature of the remaining cases of PTH varies from region to region and depends on actual epidemiological circumstances. Cases of HB, transmitted by HBsAg-negative but nevertheless HBV-infectious blood, should be considered as well as cases of HB, transmitted by vehicles other than transfusion-blood, but confusingly also classified as PTH. Hepatitis A and hepatitis due to agents not yet identified occurring in blood recipients need further investigation. In such cases it remains an open question too, whether the disease is mainly transmitted with the transfusion-blood or by other vehicles, associated with large and long-lasting wounds or hospital environments as closely as blood transfusions are.