Background and Objective. The objective of this work was to compare three methods for estimating hepatitis B virus (HBV) incidence and residual risk. Methods. Computerized blood donor records in southern Brazil were examined for the period 2004–2006. The methods for estimating HBV incidence included stand-alone HBsAg, HBsAg yield method, and an extension of the latter which added recent anti-HBc seroconversions as incident HBV cases. Results. HBV incidences for the above methods were 9.91, 20.09, and 22.93 per 100000 repeat donors, respectively. In the same order, corresponding residual risks were 1？:？62482, 1？:？30821, and 1？:？47559, respectively. First-time donors had 52 higher HBV incidence compared to repeat donors. Conclusion. Although the three methods compared produced overlapping 95% confidence intervals, their variation was considerably lower for the method which included recent anti-HBc seroconversions. First-time donors are primary cause for concern regarding HBV transmission via blood transfusion in southern Brazil. 1. Introduction There is a consensus that infection caused by hepatitis B virus (HBV) is a worldwide public health concern of high priority, given over 2 billion people who have already been infected and about 350 million of them living with a chronic infection [1]. About a million deaths per year are attributed to this infection and its complications, primarily liver cancer and cirrhosis [1, 2]. Three quarters of the world population live in high-prevalence areas for HBV [2]. In developing countries with endemic regions for this infection, such as the Southeast of Asia, China, Africa, many Middle East countries, Pacific islands, and the Amazon region, serologic surveys show that majority of the population has been infected and that 8–15% are chronic HBV carriers. Because 5–12% of the women of childbearing age have been infected with HBV, the risk of perinatal transmission reaches the level of 70–90%, resulting in many newborns infected at birth. In addition, many children are infected during childhood through direct contact with infected blood, ulcerative wounds, or saliva. Approximately one quarter of the children infected with HBV until five years of age become chronic carriers of the virus. On the other hand, adolescent and adult populations acquire HBV through sexual contacts and have between 1% and 5% risk of becoming chronic carriers [3]. Such a high disease burden is even more absurd in the light of the fact that HBV infection is preventable by affordable vaccine (about U$10 per person for the standard vaccine schedule).
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