Between 1.04 million and 1.61 million migrants now resident in the US have chronic hepatitis B infection, investigators report in the online edition of Hepatology.
“The finding that as many as 1.6 million foreign born individuals in the United States may be living with chronic hepatitis B – nearly twice the number previously estimated – highlights the need for HBV [hepatitis B virus] screening in all foreign-born persons,” write the authors.
After adding the 300,000 to 600,000 chronic hepatitis B infections in US-born individuals, the investigators suggest that there could be as many as 2.2 million chronic hepatitis B infections in the United States, a far higher figure than any other current estimate.
Chronic hepatitis B is a major global health problem. It is thought that there are between 350 and 400 million infections worldwide. Up to a quarter of people with chronic hepatitis B infection have a significant risk of premature death because of complications related to the infection.
Despite the serious health implications of the infection, the epidemiology of chronic hepatitis B in the US is poorly understood. This is partly because testing for the infection is not part of routine health care. Moreover, surveillance activities for the infection have inadequate funding and are poorly developed. Estimates of the number of chronic hepatitis B infections in the US vary from a low of 500,000 to as high as two million.
It is well recognised that many of cases of chronic hepatitis B infection involve people who were born outside the US. Between 2006 and 2008, approximately 3% of refugees entering the US were found to have the infection – this is compared to a prevalence rate of between 0.1 and 0.2% in the US-born population.
Current hepatitis B surveillance data are likely to be inaccurate because vulnerable and marginalised individuals – including those born abroad – are under-represented.
A team of investigators therefore conducted a meta-analysis, surveying the prevalence of chronic hepatitis B in 102 countries and the rate of the infection in migrants.
Some 2053 prevalence surveys were included in the study. Of these, 256 involved emigrants and 1797 examined rates of chronic hepatitis B infection among individuals still living in the country studied.
Countries with the highest prevalence of chronic hepatitis B infection were Sudan (19%), Liberia (17%), Guinea (16%), Eritrea (16%) and Zimbabwe (14%).
Rates of the infection among migrants were highest among those who emigrated from Africa (10%), followed by Asia (7%), Oceania (5%) and the Caribbean (5%).
Overall, the prevalence of chronic hepatitis B among foreign-born individuals in the US was calculated at 3.45%.
The total number of infections among foreign-born individuals living in the US in 2009 was calculated to be 1.32 million. But estimates varied from a low of just over 1 million to a high of 1.61 million.
Approximately 58% of foreign-born people with chronic hepatitis B in the US had migrated from Asia and 11% were of African origin – the infection is endemic in both these regions.
The five countries from which the largest number of individuals with the infection had migrated were China (12% of migrants), Vietnam (13%), the Philippines (7%), the Dominican Republic (11%) and Mexico (0.5%).
“The number of foreign-born individuals living with chronic hepatitis B will continue to increase with ongoing migration from countries with intermediate and high HBV endemicity,” write the authors. “Primary care physicians and general internists have an opportunity to identify foreign-born persons living with chronic hepatitis B in the United States via screening and follow-up to ensure the benefit from monitoring and treatment.”
The authors of an editorial in the same edition of Hepatology praise the study’s “convincing data”. They believe these can “help public health officials identify at-risk populations and direct prevention to communities in need of culturally appropriate services. HBV testing, followed by linkage to care and treatment, can prevent new cases of HBV infection…and improve health outcomes for persons living with hepatitis B.”
Kowdley KV et al. Prevalence of chronic hepatitis B among foreign-born persons living in the United States by country of origin. Hepatology, DOI: 10.1002/hep.24804, 2012
Ward JW et al. Hepatitis B in the United States: a major health disparity affecting many foreign-born populations. Hepatology, online edition, DOI: 10.1002/hep.25799, 2012.