WHO Hepatitis B Fact Sheet

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http://www.who.int/mediacentre/factsheets/fs204/en/

Fact sheet N°204

Revised August 2008

Hepatitis B

Key facts

Hepatitis B is a viral infection that attacks the liver and can cause severe and

chronic illness, and death.

The virus is transmitted through contact with the blood or other body fluids of

an infected person - not through casual contact.

About 2 billion people worldwide are infected with the virus and more than 350

million live with chronic liver disease.

About 25% of adults who become chronically infected during childhood later die

from liver cancer or cirrhosis (scarring of the liver) caused by the persistent

infection.

The hepatitis B virus is 50 to 100 times more infectious than HIV.

Hepatitis B virus is a primary occupational hazard for health workers.

Hepatitis B is preventable with a safe and effective vaccine.

Hepatitis B is a potentially life-threatening liver infection caused by the

hepatitis B virus. It is a major global health problem and the most serious type

of viral hepatitis. It can cause chronic liver disease and puts people at high

risk of death from cirrhosis of the liver and liver cancer.

Worldwide, an estimated two billion people have been infected with the hepatitis

B virus (HBV), and more than 350 million have chronic (long-term) liver

infections.

A vaccine against hepatitis B has been available since 1982. Hepatitis B vaccine

is 95% effective in preventing HBV infection and its chronic consequences, and

is the first vaccine against a major human cancer.

Symptoms

Hepatitis B virus can cause an 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. People can take several months to

a year to recover from the symptoms. HBV can also cause a chronic liver

infection that can later develop into cirrhosis of the liver or liver cancer.

Who is most at risk for chronic disease?

The likelihood that an HBV infection will become chronic depends upon the age at

which a person becomes infected, with young children who become infected with

HBV being the most likely to develop chronic infections. About 90% of infants

infected during the first year of life develop chronic infections; 30% to 50% of

children infected between one to four years of age develop chronic infections.

About 25% of adults who become chronically infected during childhood die from

HBV-related liver cancer or cirrhosis.

About 90% of healthy adults who are infected with HBV will recover and be

completely rid of the virus within six months; 8% to 10% of the adult population

are chronically infected. Liver cancer caused by HBV is among the first three

causes of death from cancer in men, and a major cause of cancer in women.

Where is hepatitis B most common?

Hepatitis B is endemic in China and other parts of Asia. Most people in the

region become infected with HBV during childhood. High rates of chronic

infections are found in the Amazon and the southern parts of eastern and central

Europe. In the Middle East and Indian sub-continent, an estimated 2% to 5% of

the general population is chronically infected. Less than 1% of the population

in western Europe and North American is chronically infected.

Transmission

Hepatitis B only affects humans. The virus is transmitted between people by

contact with the blood or other body fluids (i.e. semen and vaginal fluid) of an

infected person. Modes of transmission are the same for the human

immunodeficiency virus (HIV), but HBV is 50 to 100 times more infectious Unlike

HIV, HBV can survive outside the body for at least 7 days. During that time, the

virus can still cause infection if it enters the body of a person who is not

infected.

Common modes of transmission in developing countries are:

perinatal (from mother to baby at birth)

child-to-child

unsafe injections practices

blood transfusions

sexual contact

In many developed countries (e.g. those in western Europe and North America),

patterns of transmission are different than those mentioned above. Today, the

majority of infections in these countries are transmitted during young adulthood

by sexual activity and injecting drug use. HBV is a major infectious

occupational hazard of health workers.

HBV is not spread by contaminated food or water, and cannot be spread casually

in the workplace.

The virus incubation period is 75 days on average, but can vary from about 30 to

180 days. HBV may be detected 30 to 60 days after infection and persist for

widely variable periods of time.

Treatment

There is no specific treatment for hepatitis B. Care is aimed at maintaining

comfort and adequate nutritional balance, including replacement of fluids that

are lost from vomiting and diarrhoea.

Chronic hepatitis B can be treated with drugs, including interferon and

anti-viral agents, which can help some patients. Treatment can cost thousands of

dollars per year and is not available to most patients in developing countries.

Liver cancer is almost always fatal, and usually develops in people when they

are most productive and have family responsibilities. In developing countries,

most people with liver cancer die within months of diagnosis. In higher income

countries, surgery and chemotherapy can prolong life for up to a few years in

some patients.

Patients with cirrhosis are sometimes given liver transplants, with varying

success.

Prevention

All infants should receive the hepatitis B vaccine: this is the mainstay of

hepatitis B prevention.

The vaccine can be given as either three or four separate doses, as part of

existing routine immunization schedules. In areas where mother-to-infant spread

of HBV is high the first dose of vaccine should be given as soon as possible

after birth (i.e. within 24 hours).

The complete vaccine series induces protective antibody levels in more than 95%

of infants, children and young adults. After age 40, protection following the

primary vaccination series drops below 90%. At 60 years old, protective antibody

levels are achieved in only 65 to 75% of those vaccinated. Protection lasts at

least 20 years and should be lifelong.

All children and adolescents younger than 18 years old and not previously

vaccinated should receive the vaccine.

People in high risk groups should also be vaccinated, including:

persons with high-risk sexual behaviour;

partners and household contacts of HBV positive persons;

injecting drug users;

persons who frequently require blood or blood products;

recipients of solid organ transplantation;

those at occupational risk of HBV infection, including health care workers; and

international travellers to countries with high rates of HBV.

The vaccine has an outstanding record of safety and effectiveness. Since 1982,

over one billion doses of hepatitis B vaccine have been used worldwide. In many

countries where 8% to 15% of children used to become chronically infected with

HBV, vaccination has reduced the rate of chronic infection to less than 1% among

immunized children.

As of December 2006, 164 countries vaccinate infants against hepatitis B during

national immunization programmes - a major boost in coverage from 31 countries

in 1992, the year that the World Health Assembly passed a resolution to

recommend global vaccination against hepatitis B.

For more information contact:

WHO Media centre

Telephone: +41 22 791 2222

E-mail: mediainquiries@...