Journal of Viral Hepatitis, 2008, 15, 12–13 LETTER TO THE EDITOR Underestimation of chronic hepatitis B virus infection in the United States of America C. Cohen, 1 A. A. Evans, 1,2 W. T. London, 3 J. Block, 1 M. Conti1 and T. Block1,4 1Hepatitis B Foundation, Doylestown, PA; 2Drexel University School of Public Health; 3Fox Chase Cancer Center; and 4Drexel University College of Medicine, Philadelphia, PA, USA OnlineOpen: This article is available free online at www.blackwell-synergy.com Keywords: Asian and Paciﬁc Islander, hepatitis B, hepato- cellular carcinoma, immigrant, prevalence. Abbreviations: HBF, Hepatitis B Foundation; HBV, hepatitis B virus; API, Asians and Paciﬁc Islanders. Correspondence: Chari Cohen, MPH, Hepatitis B Foundation, Doylestown, PA, USA. E-mail: chari@hepb.org Dear Sir, In the December 2006 issue of Journal of Viral Hepatitis, Drs. Gish and Gadano made the important point that the current prevalence estimate of 1.25 million individuals in the USA with chronic hepatitis B virus (HBV) infection should be corrected by taking into account HBV prevalence in immigrant populations and current estimates may be as high as 2 million [1]. The Hepatitis B Foundation (HBF) agrees with this statement, that the prevalence of chronic HBV infection in the United States is, in fact, signiﬁcantly greater than the currently accepted estimate. We have per- formed our own calculation of the chronic hepatitis B prevalence estimate including the high prevalence rates of hepatitis B in immigrant populations. As a result, we esti- mate the current burden of chronic hepatitis B in the USA to be approximately 2 million people. We reason that an underestimation of the true number of infected individuals in the USA has occurred mostly because the highest-risk populations are under-represented in sur- veillance studies, and a large percentage of chronically infected individuals remain undiagnosed. Estimates of the number of HBV infections in the USA have been based on serosurvey data from the National Health and Nutrition Examination Surveys for the years 1976–1994 (NHANES II, III), which did not include signiﬁcant numbers of Asians and Paciﬁc Islanders (API, the ethnic groups most affected by hepatitis B), making it difﬁcult to obtain accurate prevalence estimates [2]. Also, the large inﬂux of foreign born individ- uals from countries with moderate or high incidence doi:10.1111/j.1365-2893.2007.00888.x of hepatitis B increases the limitation of the NHANES estimate. Using Census data (2005 American Community Survey) and current prevalence estimates for chronic hepatitis B, we calculate that in APIs alone, there are approximately 832 433 individuals chronically infected with hepatitis B (Table 1). This number was reached using hepatitis B prevalence estimates of 8.9% for foreign and 1.4% for US born APIs [3], based on HBV survey data of API pregnant women. These estimates are conservative in comparison with recent studies, which have found the prevalence among foreign-born APIs to be between 10–15% [4,5]. We calculated a chronic HBV burden of 1 157 137 individuals in the Caucasian, African American, and other ethnicities, with a prevalence estimate of 0.42% in these groups (based on NHANES III data [6]) (Table 1). Adding our estimate for the API population (832 433) brings the total burden estimate to 1 989 570. This rep- resents an increase of almost 800 000 individuals from the currently accepted HBV prevalence estimate, and it does not account for undocumented APIs, which could increase the number of chronically infected by another 100 000 (there are an estimated 1 500 000 undocu- mented APIs in the USA [7]). This calculation also does not include other high-risk groups, such as the incarcer- ated and homeless populations, which would increase the burden even further. While these calculations have limitations, they are pro- vocative, in that they highlight the strong likelihood that chronic hepatitis B remains an under-recognized disease in the USA, one that deserves greater priority from public health leaders, research institutions and clinicians. The na- tion needs to support public health surveillance systems that yield reliable state and local data and can be used to cal- culate more accurate estimates of chronic hepatitis B. As the readers of JVH are aware, chronic hepatitis B infection leads to serious liver disease and early death in up to 25% of individuals [8], and the direct and indirect ﬁnancial burden of chronic hepatitis B reaches $1 billion each year [9]. It is a leading cause of primary liver cancer (hepatocellular carcinoma), which is rising in both incidence and mortality in the USA, and now ranks 8th among leading causes of cancer death for Americans [10]. In the API pop- ulation, liver cancer ranks 3rd among causes of cancer death [11]. With the number of new infections remaining steady despite the availability of a vaccine, and the signiﬁcant rise of primary liver cancer in the USA, it is imperative that hepatitis B be prioritized as an important public health concern. An accurate assessment of the true prevalence of Journal compilation 2007 The Authors 2007 Blackwell Publishing Ltd