Countrywide variations in chronic HBV burden revealed

Sep 3 2015

By Shreeya Nanda, Senior medwireNews Reporter

A systematic review of the worldwide prevalence of chronic hepatitis B virus (HBV) infection finds wide variation between countries.

This study “highlights the need for continued prevention and control strategies and the collection of reliable epidemiologic data using standardised methodology”, Jördis Ott (Helmholtz Centre for Infection Research, Braunschweig, Germany) and co-workers write in The Lancet.

Using data from 1800 reports of hepatitis B surface antigen (HBsAg) seroprevalence across 161 countries published between 1965 and 2013, the global prevalence was estimated at 3.61%.

African and Western Pacific region countries had the highest endemicity, with total prevalence rates of 8.83% and 5.26%, respectively, while countries of the Americas and the South East Asian region were at the other end of the scale, at 0.81% and 1.90%, respectively.

HBsAg prevalence varied greatly across countries, ranging from 0.01% in the UK and Norway to 22.70% in Kiribati, which the researchers say “might be partly explained by varying risk factors and transmission routes across countries”.

Variation was also seen within World Health Organization regions – with prevalence estimates in the Americas of 0.20%, 0.22% and 0.27% in Mexico, Guatemala and USA, respectively, and 4.71% and 13.55% in Belize and Haiti, respectively.

The researchers estimate that globally 248 million people were HBsAg positive in 2010, with the greatest burden in the Western Pacific region, with an estimated 95 million chronic HBV patients, followed by the African region, which had more than 75 million HBsAg-positive individuals.

And China, India and Nigeria topped the list of countries with the highest population of HBsAg-positive people, at 74 million, 17 million and 15 million, respectively.

Compared with the prevalence between 1957 and 1989, HBV prevalence decreased in countries of the South East Asian, Western Pacific and Eastern Mediterranean regions during the 1990 to 2013 time period. But Ott et al noted trends towards increasing prevalence in some eastern European and African countries, such as Nigeria (8.52% in 1957–1989 to 9.81% in 1990–2013).

Writing in an accompanying comment, Jennifer MacLachlan (Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia) and co-authors note that the researchers excluded studies focusing on certain population groups, such as migrants from endemic areas living in countries of low endemicity. As these groups are at particular risk of chronic HBV and in some countries represent the majority of those living with HBV, “this exclusion leads to an underestimate of the total burden of HBV”, they say.

The commentators conclude that with the appropriate implementation of global policies and initiatives in the most-affected populations, “the impressive reductions in HBsAg prevalence in children vaccinated in infancy being observed can in the near future be matched by similarly profound reductions in lives being lost to chronic HBV infection each year”.

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