Chronic hepatitis B and C are the leading cause of liver disease worldwide (Perz 2006), and the second most common cause of liver disease in the UK, after alcohol.
The hepatitis B virus is transmitted perinatally from mother to child and through contact with infected blood. Some individuals clear hepatitis B infection naturally, whereas others develop a chronic infection that can result in severe liver disease. Rates of progression from acute to chronic infection vary according to age at the time of exposure. About 85% of hepatitis B infections in newborns become chronic compared with 4% in adults (Edmunds et al. 1993).
It has been estimated that 95% of people with new chronic hepatitis B in the UK are migrants, most of whom acquired the infection in early childhood in the country of their birth (Hahné et al. 2004). The remaining 5% of people with chronic hepatitis B acquired the infection in the UK, either through vertical transmission from mother to child or through exposure between adults. Migrant populations are therefore the main focus for hepatitis B case-finding in the UK, and infection in childhood is the major route of transmission. Other key risk groups for hepatitis B infection are described in Whose health will benefit?
There is considerable uncertainty about the number of people with chronic hepatitis B in the UK. In 2002 the Department of Health estimated that chronic hepatitis B affects 180,000 people in the UK (Department of Health 2002). Information on the burden of hepatitis B in England and Wales is derived from a number of sources:
laboratory reports of confirmed acute and chronic infections
serological studies of populations covered by screening programmes (that is, pregnant women and blood donors)
serological studies of populations at high risk (for example, people who inject drugs)
sentinel laboratory surveillance of people being tested
estimates of the size of the migrant population.
In 2011, 589 acute or probable acute cases of hepatitis B were reported in England (Health Protection Agency 2012). The total number of acute infections will be greater than the number reported. The most recent study to estimate the annual incidence of hepatitis B in England and Wales was conducted between 1995 and 2000 (Health Protection Agency, Hahné et al. 2004). It estimated the annual incidence of hepatitis B, from laboratory reports, to be around 7.4 per 100,000 people. This translates into around 3700 acute infections per year and around 270 cases of chronic hepatitis B per year. Information about risk factors was available for about 50% of the acute cases. The most common reported risk was heterosexual exposure, followed by homosexual exposure. In comparison, fewer than 5% of cases were attributed to injecting drug use. The decline in the number of cases linked to injecting drug use is supported by the 2011 Unlinked Anonymous Monitoring (UAM) survey, which reported a fall in the proportion of injecting drug users who had ever been infected with hepatitis B, from 28% in 2001 to 16% in 2011 (Health Protection Agency 2011c). This decrease is probably associated with an increase in the uptake of hepatitis B vaccination (Judd et al. 2007; Hope et al. 2007). According to the UAM survey, self-reported rates of hepatitis B vaccination increased from 35% in 2000 to 76% in 2011 (Health Protection Agency 2011c).
A national antenatal screening programme for hepatitis B surface antigen (HBsAg) began in 2000 (Health Protection Agency 2011a). Uptake of screening during pregnancy has increased over time (up to 97% in 2011), but the proportion of women who test positive has remained stable (0.42% in 2011).
The sentinel surveillance programme identified that 28.5% (73,290) of women who had been tested for HBsAg in 2011 were tested through antenatal screening. Overall, 0.5% of the women tested in the antenatal programme tested positive. Most of the 73,290 women in the study were white or white-British. More black or black-British women (3.9%) and women from 'other' or mixed ethnicity (3.8%) tested positive for HBsAg compared with their Asian/Asian-British (0.5%) and white counterparts (0.3%).
Hepatitis C is a blood-borne viral infection transmitted through contact with infected blood. In the UK, hepatitis C is primarily acquired through injecting drug use. Approximately 70–75% of people who are infected with acute hepatitis C develop a chronic condition that can result in liver failure and liver cancer.
The most recent national estimate suggests that around 216,000 people in the UK have chronic hepatitis C (Health Protection Agency 2012; Scottish Executive 2008). Of these, around 160,000 live in England (Harris 2012a). Injecting drug use is the main route of hepatitis C infection in England. Of the estimated number of people who are chronically infected, around 87% are current or past injection drug users. Of the remaining 13%, 6% are of South Asian descent and the other 7% are of white/other ethnicity (Harris et al. 2012a). Similarly, 90% of the total laboratory reports including risk information in the UK in 2010 attributed infection to injecting drug use (Health Protection Agency 2011c). The main focus for hepatitis C case-finding is therefore people who inject or have injected drugs. There is good evidence that HIV-positive men who have sex with men are at increased risk of hepatitis C infection, and British HIV Association guidelines recommend regular hepatitis C testing in this group. Emerging evidence suggests that people who inject image- and performance-enhancing drugs are also at increased risk of hepatitis C infection.
In England, more than 95,000 individuals had been diagnosed with hepatitis C by the end of 2011, suggesting that a significant number of infections remain undiagnosed. Hospitalisations, registrations for liver transplant and deaths from liver cancer due to hepatitis C are steadily increasing throughout the UK. In England, rates of end-stage liver disease caused by hepatitis C are likely to increase if diagnosis and treatment rates do not improve (Health Protection Agency 2012).
The prevalence of chronic disease in current and past drug users varies by region, and is highest in London and the North West (Harris et al. 2012). An analysis of the 2010 UAM survey of people who inject drugs and attend specialist services estimated the overall prevalence of hepatitis C antibodies (indicating exposure to the virus) to be 43%, but ranging from 14% to 82% in different geographical sites (Harris et al. 2012b). Data from the UAM survey also suggest that over 83% of people surveyed had a voluntary test for hepatitis C in 2010, compared with 40% in 2000. However, only about half were aware they were hepatitis C antibody positive when comparing self-reported data with anonymous test results (Health Protection Agency 2011b).
The national hepatitis B immunisation programme recommends that people from at-risk groups are immunised against hepatitis B. Post-exposure immunisation (which may include hepatitis B immunoglobulin as well as hepatitis B vaccine) is also recommended for babies born to chronically infected mothers (Department of Health 2006).
NICE recommends a number of treatments for hepatitis B and hepatitis C (see section 7). Early diagnosis and treatment can clear infection and reduce the risk of long-term complications, such as cirrhosis and liver cancer. For people with chronic hepatitis C, early therapy is associated with increased and sustained virological response rates (Foster et al. 2010).