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
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
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
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
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
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.”