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All you need to know about hepatitis B

Primary care practices need to do more to help protect patients against hepatitis B, a survey commissioned by the British Liver Trust revealed in May.(1) Carolyn Driver discusses the different vaccines currently available and the importance of addressing the health needs of child travellers

Carolyn Driver
RGN RM RHV FPCert MSc(TravelMed) FFTM RCPS(Glas)
Independent Travel Health and Immunisation Specialist Nurse Cheshire

Hepatitis B infection has a worldwide distribution (see Figure 1). It is estimated that, currently, more than two billion of the global population have been infected. Of these, approximately 360 million are chronically infected and at risk of serious illness and death from cirrhosis and hepato-cellular carcinoma, diseases that are estimated to cause 500,000-700,000 deaths each year worldwide.(2)
In 1991 the World Health Organization called for universal immunisation against hepatitis B infection by 1997.(3) Although 85% of countries in the world have done this, the UK has not.(4) Here we rely on an opportunistic approach requiring identification of those most at risk.(5) For this approach to work well it relies on knowledgeable healthcare professionals and an awareness of the disease among the population so that those at risk can present for screening and vaccination.

Hepatitis B infection
Hepatitis B is an infection of the liver caused by the hepatitis B virus (HBV). The outcomes of HBV infection are age-dependent and include acute hepatitis B, chronic HBV infection, cirrhosis and hepatocellular carcinoma (HCC). Acute hepatitis B occurs in approximately 1% of perinatal, 10% of early childhood (1-5 years old) and 30% of late (> 5 years old) HBV infections.
Fulminant hepatitis develops in 0.1-0.6% of acute hepatitis cases; mortality from fulminant hepatitis B is approximately 70%. The development of chronic HBV infection is inversely related to age and occurs in approximately 90% of people infected perinatally, in 30% infected in early childhood and in 6% infected after five years of age. The likelihood of progression to chronic infection does not differ among those with symptomatic or asymptomatic infection. People with chronic HBV infection have a 15-25% risk of dying prematurely from HBV-related cirrhosis and HCC.(2)
Many people who become chronic carriers have no symptoms and are unaware that they are infected, but will remain infectious and capable of transmitting the virus to others.
Hepatitis B virus is transmitted by contact with blood or body fluids of an infected person in the same way as human immunodeficiency virus. However, HBV is 50-100 times more infectious than HIV and the virus can remain infectious on hard surfaces for more than a week. The main routes of transmission of HBV include:

  • Perinatal (from mother to baby at birth).
  • Child-to-child transmission.
  • Unsafe injections and transfusions.
  • Sexual contact.

Worldwide, most infections occur from infected mother to child, from child-to-child contact in household settings, and from reuse of unsterilised needles and syringes. In many developing countries, almost all children become infected with the virus. In industrialised countries the pattern of transmission is different. The majority of infections in these countries are acquired during young adulthood by sexual activity and injecting drug use. However, perinatal transmission may account for 15% of HBV-related deaths, even in low-endemic areas.(2)

The situation in the UK
The UK is considered to be an area of low prevalence for HBV although this does vary across the country. Currently the Department of Health recommends pre-exposure hepatitis B vaccination for the following:(5)

  • Intravenous drug users.
  • Individuals who change sexual partners frequently.
  • Close family contacts of a case or individual with chronic hepatitis B infection.
  • Families adopting children from countries with a high or intermediate prevalence of hepatitis B.
  • Foster carers.
  • Individuals receiving regular blood or blood products and their carers.
  • Patients with chronic renal failure.
  • Patients with chronic liver disease.
  • Inmates of custodial institutions.
  • Individuals in residential accommodation for those with learning difficulties.
  • People travelling to or going to reside in areas of high or intermediate prevalence (see Figure 1). 
  • Individuals at occupational risk, eg, healthcare workers.
  • Postexposure immunisation is recommended for:
  • Babies born to mothers who are chronically infected with HBV or to mothers who have acute hepatitis B during pregnancy. In the UK antenatal screening for HBV is now offered to all mothers; however, there is some evidence that follow-up of results is patchy.
  • Any individual who is potentially exposed to hepatitis B-infected blood or body fluids.

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Children
From the above it can be seen that the UK approach to control the spread of HBV relies on identification of those at risk. Young children and infants are a particularly vulnerable group as they have the greatest chance of becoming chronic carriers and thus succumbing to serious, life-threatening consequences. Children can also transmit the infection horizontally and thus a chronically infected child in a playgroup or nursery could pose a risk to others. 
Although the main responsibility for monitoring HBV infection and following up contacts lies with the Health Protection Agency, it is vital that all primary healthcare professionals play their part in identifying those potentially at risk and educating and screening them when appropriate. There should be a named person in each local health protection unit who can be consulted for information on local policy.(6) Staff in general practice can play an important role in identifying migrant families who may come from a part of the world where HBV infection is of intermediate-to-high endemicity.
In 2006, 21.9% of live births in the UK were to mothers born outside the UK and this figure is not likely to diminish with current migration trends. It is important that these women are encouraged to consent to screening and agree to their infants and other family members being vaccinated when necessary. The Department of Health has recently updated the leaflet "Hepatitis B, how to protect your baby". This leaflet is now available in the following languages: Arabic, Bengali, Cantonese, French, Greek, Gujarati, Hindi, Portuguese, Punjabi, Somali, Swahili, Turkish, Urdu and Vietnamese.
Completion of the course of vaccines is also essential and again primary care staff can play a vital role in this respect.
Current guidelines for vaccinating neonates born to hepatitis B-infected mothers can be found in the Green Book Immunisation Against Infectious Disease.(5) Where at all possible vaccination should be commenced at birth and most infants will also require hepatitis B immunoglobulin, which is preferably administered within 24 hours of birth. All infants born to HBV-infected mothers should be referred to a liver specialist for monitoring.

Hepatitis B vaccination and overseas travel
The National Travel Health Network and Centre (NaTHNaC) states in its country profiles for all intermediate and high-risk countries for HBV that vaccination should be considered for all travellers.(7) It is essential that all travellers are educated about the mode of transmission of this disease and the prevalence of the infection at their destination. They should also be aware of the availability of a safe and effective vaccination.
Parents taking children abroad should be aware of the nonsexual routes of transmission. This is particularly important for those travellers visiting friends or family abroad (VFRs). Statistically they tend to stay longer and may have much closer contact with the local population than tourists. In the review The incidence and routes of transmission of hepatitis B virus in England and Wales, 1995-2000: implications for immunisation policy, the authors identified that travellers of Asian ethnic origin, including children, had acquired hepatitis B infection while visiting South Asia.8 Medical treatment was cited as the most likely source of infection. The same report also highlighted that the most common mode of transmission to hepatitis B-infected children in the UK is through another household member.
All children are vulnerable to illness and accidents and thus all parents regardless of ethnicity who are taking their children to areas of intermediate or high risk should consider vaccination. Currently hepatitis B vaccine given purely because of travel abroad is considered a private chargeable vaccine in many areas, which can create another barrier to its use. Healthcare professionals need to develop skills to help overcome these barriers. It is also arguable that they should lobby locally to change a policy that treats those travelling abroad unequally to other at-risk groups.

Immunisation options
There are now a number of different vaccines available for use in the UK (see Table 1).

  • All the available vaccines are inactivated products designed for intramuscular administration.
  • The preferred site is the deltoid in all recipients over the age of 12 months. The anterolateral aspect of the thigh should be used in infants under one year.
  • They can be administered at the same time (but at a different site) to all other vaccines, including hepatitis B immunoglobulin.
  • Schedules should be adhered to as closely as possible, but there is no need to restart a course where there has been a longer than recommended gap between doses.
  • Where possible complete the course with the same brand of vaccine; however, there is good evidence that in the case of the single antigen vaccines, changing brands will not affect the immune response.5 However, as the two combined paediatric hepatitis A and B vaccines currently available contain different antigen doses, courses of these should continue with the same brand.
  • The only contraindication to hepatitis B-containing vaccines is a history of anaphylaxis to a previous dose of the vaccine or to a constituent of the product.
  • Hepatitis B vaccines can be given to those who are immunosuppressed; however, their immune response may be suboptimal and thus compliance with the full course is vital. Preterm babies often do not respond as well as those born at term so a preterm infant born to a hepatitis B-infected mother should be followed up rigorously to ensure completion of the course and to check for seroconversion.
  • Serology should be performed at one year of age to check for seroconversion in infants born to hepatitis B-infected mothers. This may be done when they attend for their fourth dose of vaccine.
  • A single booster dose should be given at the same time as the preschool booster to children born to hepatitis B-infected mothers.
  • A single booster five years after a primary course is currently recommended for all other groups.

[[nip43_table1_86]]

Complete long-lasting immunity can only be certain following a complete course of vaccination and thus it is important to encourage attendance for the complete course. The fourth dose in an accelerated schedule can often be forgotten so practitioners should set up recall systems for these doses. Travellers rarely attend in time for longer courses of vaccination, but the WHO reports that due to the long incubation period of the infection, two doses of vaccine given one month apart may offer reasonable protection providing the third dose is given as soon as possible following travel.(9)

Conclusion
Hepatitis B is a preventable infection that can have serious implications, especially when acquired in infancy or early childhood. The current UK strategy for preventing this disease relies on a proactive approach to identify those at risk and thus healthcare professionals in the primary sector should be familiar with their local policies and ensure that all at-risk individuals are
appropriately educated and vaccinated.

References

  1. Nurses urged to protect against hepatitis B [news item]. 19 May 2008. Available from http://www.nursinginpractice.com
  2. World Health Organization. Weekly Epidemiological Record. Hepatitis B vaccines. Weekly Epidemiological Record 2004;79:253-64.
  3. World Health Organization.  Fact sheet no 204. Hepatitis B. Available from: http://www.who.int/mediacentre/factsheets/fs204/en/
  4. Pendleton S, Wilson-Webb P. Rising curve: chronic hepatitis B infection in the UK. Canterbury: Hepatitis B Foundation; 2007.
  5. Salisbury D, Ramsay M, Noakes K. Immunisation against infectious diseases. London: Department of Health; 2006. ch. 18.
  6. Health Protection Agency. Standards for local surveillance and follow up of hepatitis B and C. London: HPA; 2006.
  7. NaTHNaC. Country map. Available from: http://www.nathnac.org/ds/map_world.aspx
  8. Hahnéa S, Ramsay M, Balogun K, et al. Incidence and routes of transmission of hepatitis B virus in England and Wales, 1995-2000: implications for immunisation policy. J Clin Virol 2004;29:211-20.
  9. World Health Organization. International travel and health 2008. Geneva: WHO; 2008.