We would like to acknowledge H. Wedemeyer, B. Heidrich, and M. P. Manns for their comments and believe that it is important to consider that HDV is not a vanishing disease in several countries of Europe.1 Indeed, in France too, we agree that the surveillance of hepatitis D has to be performed. It is however very difficult to obtain a good estimation of the prevalence of HDV among people infected by HBV. HDV is still not a major health problem in HBsAg-negative HBV-infected patients;2, 3 therefore, we encourage the search for HDV status at least once in the medical survey of an HBs-positive carrier. Search for total anti-delta antibodies in the serum might be sufficient for initial screening. Then the next question may be what proportion of patients with anti-HDV have ongoing replication of HDV? (i.e., patients who would be at risk of transmission and of potential liver damage and might get benefit from treatment). Considering results in 2005, among 122 new patients with serological reactivity for total HDV antibodies, 62 (50%) had a positive detection of HDV RNA using the recently described TaqMan-based real-time PCR approach.4
The graphs in Fig. 1 can be generated from results obtained at the “Laboratoire Associé au Centre National de Référence des Hépatites B, C” in France during the last 5 years by considering patients with detectable HDV RNA registered for the first time. Among 617 patients analyzed, the situation seems quite different than in Germany. Indeed, the proportion of HDV-infected patient from Western Europe is decreasing as described for Italy,1 but we do not observe such a high prevalence of HDV-infected people from Eastern Europe, which represents in France only 12% in 2006. In contrast, new infection recognized as HDV concerns mostly African people migrating to France. This phenomenon leads us to extensively characterize the variability of HDV in Africa during recent years.5, 6 The results encourage a new HDV classification in which the Deltavirus genus consists of 8 major clades, 5 of them being present in Africa (i.e., clade 1, 5, 6, 7, and 8).7 Interestingly, clade 5 isolates represent approximately 20% of HDV RNA–positive samples, which is stable for the time period in France. Collaborative studies that include a large number of HDV-infected patients will be necessary to evaluate whether HDV clades are associated with different response to pegylated interferon.