Hepatitis B

• Introduction
• Epidemiology
• Risk for Travellers
• Transmission
• Signs and symptoms
• Treatment
• Prevention
• Vaccine information
• References
• Reading List

Introduction

Hepatitis B virus is one of the most prevalent viruses worldwide and is a major cause of chronic liver disease and hepatocellular carcinoma. It is a hepadnavirus, consisting of a core antigen surrounded by a surface antigen that is the basis of the hepatitis B vaccine .

Epidemiology

(Data from the Travel Health Surveillance Section of the Health Protection Agency Communicable Disease Surveillance Centre)

Global Epidemiology

The hepatitis B virus (HBV) can cause acute inflammation of the liver, asymptomatic infection or chronic liver disease. Between 2% and 10% of adults who acquire HBV become chronically infected and can develop cirrhosis and/or liver cancer.

The prevalence of chronic hepatitis B infection varies worldwide. In sub-Saharan Africa , most of Asia and the western Pacific 8% to 10% of people are chronically infected. The Amazon and southern parts of eastern and central Europe have a rate of chronic HBV infection between 2% and 7%, and approximately 5% of people are infected in India and the Middle East . In Australia , New Zealand , northern and western Europe, and north America , the prevalence of chronic hepatitis B viral infection is under 2% of the general population.

The World Health Organization (WHO) estimates that there are approximately 350 million carriers of HBV worldwide [1].

Global distribution of hepatitis B, 2002 (map reproduced with acknowledgement to the World Health Organization)

Countries/areas with moderate to high risk of infection

 Hepatitis B in travellers from England and Wales

Figure 1 Laboratory reports of acute hepatitis B by travel history, England and Wales , 1987 - 2002 (1)

Figure 1 shows the total laboratory reports of hepatitis B reported to CDSC from 1987 to 2002 by history of travel. The numbers of cases have remained constant over this period with no particular trend. However, the number of reports where a travel history has not been stated has increased from around 40% in 1989 to 75% in 2002. This is probably due to changes in automated data laboratory collection systems, which may have led to loss of information on risk factors. On average, just under 40% of reports with travel history information specified travel abroad; this proportion has remained fairly steady over time.

Figure 2 Laboratory reports of cases of acute hepatitis B acquired abroad in England and Wales 1987 - 2002*

* Data for 2002 is provisional

Figure 2 shows the laboratory reports of hepatitis B, which are known to have been acquired abroad. From 1990, the number of reports associated with travel decreased, but it is not possible to say whether this is a real decrease or due to of lack of information about travel. Therefore these figures must be interpreted with caution.

Figure 3 Laboratory reports of acute hepatitis B by country acquired, England and Wales 1991 to 2002*

* Data for 2002 is provisional

Figure 3 shows the laboratory reports of hepatitis B by country acquired where the country has been stated. The majority of the reports are acquired in Europe , the Indian sub-continent, the Far East and Africa . The most infections acquired in Europe were from western Europe. However, towards the end of the 1990s, there has been an increase in the number of infections acquired in eastern Europe. The numbers are small and this data will reflect both travel patterns and the relative risk of contracting hepatitis B in certain countries. It must also be noted that cases of HBV acquired abroad include those who have migrated to England and Wales from abroad as well as short term travellers from England and Wales .

Further information is available from the HPA/NaTHNaC report ' Illness in England , Wales , and Northern Ireland associated with foreign travel - a baseline report to 2002 ' Available online at http://www.hpa.org.uk/ [2].

Risk for Travellers

The risk of hepatitis B for tourists is considered to be low. However, this risk will increase with certain activities, for example unprotected sexual intercourse, receiving blood transfusions in countries that do not screen donated blood and sharing needles by injecting drug users. Working in medical settings and receiving injections or body piercings may also increase the risk.

The risk among long-term travellers is higher, with estimates of acquiring symptomatic hepatitis B ranging from 0.2 per 1,000 travellers per month in Africa and Latin America , to 0.6 per 1,000 in Asia .

Back to top

Transmission

The virus can be found in bodily fluids and is transmitted percutaneously or by close sexual contact.

The percutaneous route of transmission includes the use of contaminated medical, dental or other instruments and transfusion of infected blood products.

Sexual transmission is a particularly high risk amongst men who have sex with men.

The virus can also be passed vertically from a mother to child. This is the most common mode of transmission world-wide.

There is no evidence that insect borne transmission occurs .

Signs and Symptoms

In the majority of cases, hepatitis B is a sub-clinical illness, with less than 10% of children and between 30-50% of adults suffering symptomatic disease.

Symptomatic patients will experience, following an incubation period of 6 weeks to 2 months, anorexia, nausea and vomiting and sometimes rash. They will then become jaundiced. The case fatality rate is about 1% and occurs in persons with fulminant hepatitis. This increases with age.

Following acute infection approximately 1-10% of adults will develop chronic hepatitis B. Fifteen to twenty-five per cent of those with chronic hepatitis B infection will progress to cirrhosis or hepatocellular carcinoma and die. It is also possible to become an asymptomatic carrier of hepatitis B.

Treatment

There is no specific treatment for acute hepatitis B, but rather supportive intervention.

Antiviral agents can be used in some patients to treat chronic hepatitis B. The response rate is variable and long term therapy is often required.

Prevention

All travellers should receive the following advice to reduce their risk.

• Refrain from unprotected sexual intercourse.
• Avoid tattooing, piercing and acupuncture unless it is certain that sterile needles are being used.
• Take out adequate travel insurance that will provide repatriation if necessary.
• Never share unsterilised needles.
• Exercise body fluid precautions if working in a medical setting
• Carry a sterile medical kit for use by medical staff if necessary.  

Travellers should be aware that using precautions against hepatitis B will prevent other blood and bodily fluid borne viruses, such as HIV and hepatitis C, for which there are no vaccines available.

A vaccine is available for those travellers considered to be at risk of hepatitis B.

References

1. World Health Organization. Hepatitis B factsheet No 204. Revised October 2000. WHO: Geneva .
2. Health protection Agency. Illness in England , Wales , and Northern Ireland associated with foreign travel - a baseline report to 2002. London : HPA, 2004. Available online at http://www.hpa.org.uk/.

Reading List

• Department of Health. Immunisation against Infectious Disease. 1996; HMSO London
• Kumar P, Clark M. Clinical Medicine, fifth edition. 2002
• Chin, J. Control of Communicable Diseases Manual, 17 th edition. 2000