Hepatitis B (Human)
Primary reference(s)
WHO, 2020. Hepatitis B. World Health Organization (WHO). Accessed 8 November 2020.
Additional scientific description
Hepatitis B is the most serious type of viral hepatitis. In highly endemic areas, the Hepatitis B virus (HBV), which is highly contagious, is most commonly spread from mother to child at birth (perinatal transmission), or through horizontal transmission (exposure to infected blood), especially from an infected child to an uninfected child during the first five years of life (WHO, 2016a).
Hepatitis B is also spread by needlestick injury, tattooing, piercing and exposure to infected blood and body fluids, such as saliva and, menstrual, vaginal, and seminal fluids. Sexual transmission of hepatitis B may occur, particularly in unvaccinated men who have sex with men and heterosexual persons with multiple sex partners or contact with sex workers (WHO, 2020).
The incubation period of the HBV is 75 days on average but can vary from 30 to 180 days. Most people do not experience any symptoms when newly infected. However, some have acute illness with symptoms that last several weeks, including yellowing of the skin and eyes (jaundice), dark urine, extreme fatigue, nausea, vomiting and abdominal pain. A small subset of persons with acute hepatitis can develop acute liver failure, which can lead to death (WHO, 2020).
In some people, the HBV can also cause a chronic liver infection that can later develop into cirrhosis (a scarring of the liver) or hepatocellular carcinoma (liver cancer). Infection in adulthood leads to chronic hepatitis in less than 5% of cases, whereas infection in infancy and early childhood leads to chronic hepatitis in about 95% of cases (WHO, 2020).
Laboratory confirmation of hepatitis B diagnosis is essential. A number of blood tests are available to diagnose and monitor people with hepatitis B. They can be used to distinguish acute and chronic infections (WHO, 2020).
The World Health Organisation (WHO) has published surveillance standards for hepatitis B (WHO, no date).
Metrics and numeric limits
The prevalence of hepatitis B is highest in the WHO Western Pacific Region and the WHO African Region, where 6.2% and 6.1% of the adult population is infected respectively (WHO, 2020).
In the WHO Eastern Mediterranean Region, the WHO South-East Asia Region and the WHO European Region, an estimated 3.3%, 2.0% and 1.6% of the general population is infected, respectively (WHO, 2020).
In the WHO Region of the Americas, 0.7% of the population is infected (WHO, 2017).
The WHO estimates that in 2015, 257 million people were living with chronic hepatitis B infection (defined as hepatitis B surface antigen positive) (WHO, 2019). It is estimated that about 887,000 people die each year due to consequences of hepatitis B (WHO, 2017).
HBV-HIV coinfection: about 1% of persons living with HBV infection (2.7 million people) are also infected with human immunodeficiency virus (HIV). Conversely, the global prevalence of HBV infection in HIV-infected persons is 7.4% (WHO, 2019).
Key relevant UN convention / multilateral treaty
International Health Regulations (2005), 3rd ed. (WHO, 2016b).
Examples of drivers, outcomes and risk management
Hepatitis B is a major global health problem (WHO, 2018). However, there is still limited access to diagnosis and treatment of hepatitis B in many resource-constrained settings. In 2016, 10.5% (27 million) of those infected were aware of their infection. Of those diagnosed, the global treatment coverage is 16.7% (4.5 million). Many people are diagnosed only when they already have advanced liver disease (WHO, 2019, 2020).
A safe and effective vaccine that offers 98–100% protection against hepatitis B is available and is the mainstay of prevention worldwide (WHO, 2020).
The WHO recommends that all blood donations be tested for hepatitis B to ensure blood safety and avoid accidental transmission to people who receive blood products (WHO, 2020).
For World Hepatitis Day 2020, the WHO focused on the theme ‘Hepatitis-Free Future’ to highlight the importance of addressing the prevention of mother-to-child transmission of HBV; to launch new guidance; and to call for increased domestic and international programming and funding to prevent hepatitis B mother-to-child transmission, as well as to expand access to hepatitis prevention, testing and treatment services, with a view to achieving the 2030 elimination targets (WHO, 2020).
References
WHO, no date. Immunizations, Vaccines and Biologicals: WHO-recommended Surveillance Standard of Acute Viral Hepatitis. World Health Organization (WHO). Accessed 21 November 2019.
WHO, 2016a. Technical considerations and case definitions to improve surveillance for viral hepatitis: technical report. World Health Organization (WHO). Accessed 18 February 2020.
WHO, 2016b. International Health Regulations (2005), 3rd ed. World Health Organization (WHO). Accessed 26 September 2020.
WHO, 2017. Global Hepatitis Report 2017. World Health Organization (WHO). Accessed 18 February 2020.
WHO, 2018. Immunizations, Vaccines and Biologicals: Hepatitis B. World Health Organization (WHO). Accessed 21 November 2019.
WHO, 2019. Progress report on HIV, viral hepatitis and sexually transmitted infections 2019: accountability for the global health sector strategies, 2016–2021. World Health Organization (WHO). Accessed 18 February 2020.
WHO, 2020. Hepatitis B. World Health Organization (WHO). World Health Organization (WHO). Accessed 8 November 2020.