How do people get infected ?
Hepatitis B virus is transmitted by contact with blood or body fluids of an infected person in the same way as human immunodeficiency virus (HIV), the virus that causes AIDS. However, HBV is 50 to 100 times more infectious than HIV.
The main ways of getting infected with HBV are:
- Perinatal (from mother to baby at the birth)
- Child-to-child transmission
- Unsafe injections and transfusions
Worldwide, most infections occur from infected mother to child, from child to child contact in household settings, and from reuse of unsterilized needles and syringes. In many developing countries, almost all children become infected with the virus.
In many industrialized countries (e.g. Western Europe and North America), the pattern of transmission is different. In these countries, mother-to-infant and child-to-child transmission accounted for up to one third of chronic infections before childhood hepatitis B vaccination programmes were implemented. However, the majority of infections in these countries are acquired during young adulthood by sexual activity, and injecting drug use. In addition, hepatitis B virus is the major infectious occupational hazard of health workers, and most health care workers have received hepatitis B vaccine.
Hepatitis B virus is not spread by contaminated food or water, and cannot be spread casually in the workplace.
Can chronic hepatitis B and liver cancer be treated?
Liver cancer is almost always fatal, and usually develops between 35 and 65 years of age, when people are maximally productive and with family responsibilities. The loss of a mother or a father in a developing country can devastate the entire family. In developing countries, most people with liver cancer die within months of diagnosis. In industrialized countries, surgery and chemotherapy can prolong life up to a few years. Chronic hepatitis B in some patients is treated with drugs called interferon or lamivudine, which can help some patients. However, interferon or lamivudine therapy costs thousands of dollars and will never be available to most patients in developing countries. Patients with cirrhosis are sometimes given liver transplants, with varying success. It is preferable to prevent this disease with vaccine than to try and cure it.
How safe and effective is the vaccine?
Hepatitis B vaccine has an outstanding record of safety and effectiveness. Since 1982, over one billion doses of hepatitis B vaccine have been used worldwide. The vaccine is given as a series of three intramuscular doses. Studies have shown that the vaccine is 95% effective in preventing children and adults from developing chronic infection if they have not yet been infected. In many countries where 8% to 15% of children used to become chronically infected with HBV, the rate of chronic infection has been reduced to less than 1% in immunized groups of children.
How is WHO trying to control hepatitis B?
Since 1991, WHO has called for all countries to add hepatitis B vaccine into their national immunization programmes. As of March 2000, 116 countries had included hepatitis B vaccine in their national programmes including most countries in
- Eastern and South- East Asia,
- the Pacific Islands,
- Australia,
- North and South America,
- Western Europe and the Middle East.
However, many low income countries in sub-Saharan Africa, the Indian subcontinent and in the Newly Independent States do not use the vaccine. The price of the hepatitis B vaccine has been one of the main obstacles to its introduction in many of these countries.
The Global Alliance for Vaccines and Immunization (GAVI) was created in 1999. It is a unique coalition of public and private institutions where WHO has taken a leading role. The main mission of GAVI is to vaccinate as many children as possible against vaccine-preventable diseases. GAVI has introduced a new approach to international health funding: the Global Fund for Children's vaccines (GFCV). This fund will help 74 low-income countries to reinforce their national vaccine programmes and introduce hepatitis B, yellow fever and haemophilus influenzae type b(Hib) vaccines into their national immunization programmes.
How many people are affected by hepatitis B?
Worldwide, more than two billion people (1 out of 3 people) have been infected with hepatitis B
and approximately 350 to 400 million people have developed chronic infection.2 These chronically
infected persons are at high risk of death from cirrhosis of the liver and liver cancer. About one
million people die each year from hepatitis B and its complications.3
In the United States, more than 12 million people (1 out of 20 people) have been infected with
hepatitis B, and approximately 1.25 million people have developed chronic infection. Each year
approximately 100,000 new people become infected with the disease and more than 5,000
Americans die from hepatitis B-related liver complications, including cirrhosis and hepatocellular
carcinoma (HCC). It is estimated that one U.S. health care worker dies each day from hepatitis B.
How is hepatitis B transmitted?
Hepatitis B is the most common serious liver infection in the world. The virus is transmitted
vertically through blood or body fluids from an infected woman to her newborn during the delivery
process, or horizontally via infected blood products, unprotected sex and intravenous drug use with
unsterile needles.
What is chronic hepatitis B?
About 5 to 10 percent of hepatitis B-infected adults will develop chronic infection.1 If a person tests
positive for the hepatitis virus (HBsAg) for more than six months, then they are diagnosed as being
chronically infected.2 The risk of death from HBV-related liver cancer or cirrhosis is approximately
25 percent for those who became chronically infected during childhood.3 While primary liver
cancer, or hepatocellular carcinoma (HCC), is fairly uncommon in the United States and Europe, it
is among the top three causes of cancer deaths in many Asian and some African countries.
According to the World Health Organization, more than half a million people worldwide die each year from primary liver cancer, and up to 80 percent of liver cancers are due to hepatitis B.3
What are symptoms of hepatitis B?
Of hepatitis-B infected adults, about 40 percent will show no signs of symptoms.4 Those who do
have symptoms often mistake hepatitis B infection for the flu. The most common symptoms
include:
- Fever
- Fatigue
- Muscle aches
- Appetite loss
- Nausea
- Jaundice
Is there a cure for chronic hepatitis B?
There is no cure for chronic hepatitis B. Once transmitted, the virus will always stay
present in the body though it may be suppressed to imperceptible levels. Fortunately, the
disease is preventable and many children today begin a series of vaccinations at birth.
Vaccination is the primary mode of intervention to prevent the contraction and spreading
of chronic hepatitis B.
What are the goals for treatment against chronic hepatitis B?
Medications have been introduced to fight chronic hepatitis B infection. The primary goal of
antiviral therapy for chronic hepatitis B infection is the suppression of viral replication, as
measured in the reduction of HBV DNA levels, and the prevention of disease progression to liver
cancer. Reducing viral load and enhancing the body’s natural immune response can lower the risk
of liver damage. According to a recent treatment algorithm for the management of chronic
hepatitis B infection in the United States that was published in the February 2004 issue of
Clinical Gastroenterology and Hepatology, important considerations in determining whether to
treat a particular patient include both HBV DNA levels and alanine aminotransferase (ALT)
levels.
