Important Facts 1. Hepatitis B is a viral infection that damages the liver and can cause acute or chronic disease. 2. The virus is transmitted through contact with blood or other body fluids of an infected person. 3. An estimated 240 million people are chronically infected with hepatitis B (hepatitis B surface antigen positive for at least 6 months). 4. More than 780,000 people die each year from complications of hepatitis B, including cirrhosis and liver cancer. 5. Hepatitis B is a major occupational hazard affecting health workers. 6. However, hepatitis B can be prevented by immunization with available safe and effective vaccines. Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus. It is a serious global health problem. It can cause chronic infection and patients are at high risk of dying from cirrhosis and liver cancer. A hepatitis B vaccine has been available since 1982. The hepatitis B vaccine is 95% effective in preventing infection and the development of chronic disease and liver cancer caused by hepatitis B. Geographic Distribution Hepatitis B prevalence is highest in sub-Saharan Africa and East Asia. Between 5% and 10% of the adult population in these two regions is chronically infected with hepatitis B. Amazonian and southern Central and Eastern European regions also have a high prevalence of chronic infection. In the Middle East and the Indian subcontinent, an estimated 2-5% of the population is chronically infected. Less than 1% of the population in Western Europe and North America is chronically infected. Transmission The hepatitis B virus can survive outside the body for at least 7 days. During this time, if the virus enters the body of a person who has not been vaccinated against hepatitis B, it can still cause infection. The incubation period of the hepatitis B virus averages 75 days, but may range from 30 to 180 days. Hepatitis B virus can be detected 30 to 60 days after infection and may persist and develop into chronic hepatitis B. In highly endemic areas, the hepatitis B virus can be detected in people who have not been vaccinated. In hyperendemic areas, the most common routes of transmission of hepatitis B virus are mother-to-child (perinatal transmission) or horizontal (contact with infected blood) transmission during labor and delivery, especially from infected toddlers to uninfected toddlers in the first five years of life. It is common for infants infected by their mothers and those infected before the age of five to develop chronic infection. Hepatitis B can also be transmitted through skin or mucous membrane contact with infected blood and various body fluids, as well as through saliva, menstrual blood, vaginal fluids, and semen. Hepatitis B may also be sexually transmitted, especially by unvaccinated men who have sex with men and heterosexuals who have multiple sexual partners or contact with sex workers. Infection in 5% of adults leads to chronic hepatitis. Transmission of the virus may also occur in healthcare settings or in situations where injecting drug users reuse needles and syringes. In addition, infections can occur during medical, surgical, and dental procedures and tattooing, or through the use of razors or other types of objects contaminated with infected blood. Symptoms Most people do not have any symptoms during an acute infection. However, some people have an acute illness with symptoms that can last for several weeks, including yellowing of the skin and eyes (jaundice), dark-colored urine, extreme fatigue, nausea, vomiting, and abdominal pain. A small number of people with acute hepatitis also develop acute liver failure and die. Hepatitis B virus may cause chronic liver infections in some people, which may later develop into cirrhosis or liver cancer. More than 90% of healthy adults infected with the hepatitis B virus recover spontaneously within a year. Who is at risk for chronic disease? The likelihood of a hepatitis B virus infection becoming a chronic disease depends on a person’s age at the time of infection. Children under 6 years of age who are infected with the hepatitis B virus have the greatest likelihood of becoming chronically infected: 1) about 80-90% of infants infected with the virus in the first year of life become chronically infected; and 2) 30-50% of children infected before age 6 become chronically infected. Adults: 1) Less than 5% of healthy adults infected with hepatitis B virus become chronically infected; 2) 20-30% of chronically infected adults develop cirrhosis and/or liver cancer. Diagnosis It is clinically impossible to differentiate hepatitis B from hepatitis caused by other viral agents. Therefore, the diagnosis must be confirmed by laboratory tests. Several blood tests can be used to diagnose and monitor patients with hepatitis B. The diagnosis can be made using a variety of methods. This can be used to differentiate between acute and chronic infections. Laboratory diagnosis of hepatitis B infection is made primarily by testing for hepatitis B surface antigen (HBsAg). WHO recommends that all donated blood be tested for hepatitis B to ensure blood safety and to prevent inadvertent transmission to transfusion recipients. 1) Acute hepatitis B virus infection is characterized by the presence of hepatitis B surface antigen and immunoglobulin M (IgM) anti-core antigen antibodies. In the early stages of infection, patients may also be seropositive for hepatitis B e antigen (HBeAg). Hepatitis B e antigen is usually a marker of active viral replication. The presence of Hepatitis B e antigen indicates that the infected person’s blood and body fluids are highly infectious. 2) Chronic infection is characterized by the persistence of hepatitis B surface antigen (with or without hepatitis B e antigen) for at least 6 months. The persistence of hepatitis B surface antigen is a major risk marker for the development of chronic liver disease and, later in life, hepatocellular carcinoma (liver cancer). Treatment There is no specific treatment for acute hepatitis B. Therefore, the goal of treatment is to keep the body comfortable and maintain an adequate nutritional balance, including replacing fluids lost through vomiting and diarrhea. Treatment can be given with medications including oral antiviral drugs. Treatment slows the progression of cirrhosis, reduces the incidence of liver cancer and improves long-term survival. The WHO recommends the use of oral drugs – tenofovir or entecavir – because they are the most effective drugs for suppressing the hepatitis B virus. Compared to other drugs, they rarely lead to drug resistance, are easy to take (one tablet a day) and have few side effects, so only limited monitoring is needed. However, for most people, this treatment does not cure the hepatitis B infection, but only suppresses the replication of the virus. Therefore, most people who start hepatitis B treatment must take the medication for the rest of their lives. Treatment with interferon may be considered for some people in high-income settings, but its use is less feasible in low-resource settings due to the high cost of interferon and the presence of significant side effects that require careful monitoring of medication use. Hepatitis B diagnosis and treatment is difficult to obtain in many resource-limited settings, and many people are diagnosed only after they develop advanced liver disease. Liver cancer progresses rapidly and regression is often poor due to limited treatment options. In low-income settings, most people with liver cancer die within months of diagnosis. In high-income countries, with surgery and chemotherapy, patients’ lives can be extended by several years. In high-income countries, patients with cirrhosis sometimes receive liver transplants, with varying degrees of success. Prevention Vaccination against hepatitis B is the primary method of prevention. WHO recommends immunizing all infants against hepatitis B as early as possible after birth, preferably within 24 hours. This should be followed by two or three doses to complete the full basic immunization schedule. In most cases, either one of the following two options is available: 1) the three-dose method, in which the newborn receives the first dose (monovalent vaccine) at birth, and the second and third doses (monovalent vaccine or combination vaccine) are given at the same time as the first and third doses, respectively, of the DPT vaccine; or 2) the four-dose method, in which the newborn receives one dose of the monovalent vaccine at birth, and then receives three doses of the monovalent vaccine or combination vaccine, usually at the same time as the other routine childhood vaccinations. vaccines, usually given at the same time as other routine childhood vaccines. More than 95% of infants, children, and young adults who receive the full series of vaccines develop antibodies in their bodies that reach protective levels. Protection lasts for at least 20 years and may be lifelong. Therefore, WHO does not recommend catch-up vaccination for people who have completed the 3-dose vaccination program. All children and unvaccinated adolescents under 18 years of age in countries with low or moderate epidemics should be vaccinated. An increasing number of people in high-risk groups in these countries are likely to be infected, so they should also be vaccinated. These include: 1) people who require frequent use of blood or blood products, dialysis patients, and solid organ transplant recipients; 2) inmates in prisons; 3) injecting drug users; 4) family members and sexual contacts of chronically infected people with hepatitis B virus; 5) people with multiple sexual partners; 6) health care workers and others who may be occupationally exposed to blood and blood products; and 7) travelers who have not yet completed the full course of hepatitis B vaccination. Travelers who have not yet completed the full course of hepatitis B vaccination should be vaccinated before traveling to areas where hepatitis B is endemic. The vaccine has an excellent record of safety and efficacy. Since 1982, more than 1 billion doses of hepatitis B vaccine have been administered worldwide. In many countries where 8 to 15 per cent of children had become chronically infected with hepatitis B virus, chronic infection among vaccinated children has now been reduced to less than 1 per cent through vaccination. As of 2013, 183 Member States had immunized infants against hepatitis B as part of their immunization schedules, and 81 per cent of children had received the vaccine. The number of countries is significantly higher than the level of 31 countries in 1992. That year, the World Health Assembly adopted a resolution recommending global vaccination against hepatitis B. In addition, as of 2013, a total of 93 Member States had administered the first dose of hepatitis B vaccine to newborns. In addition, the implementation of blood safety strategies, including quality-assured screening of all donated blood and blood components for transfusion, can prevent the transmission of the hepatitis B virus. Performing safe injections and eliminating unnecessary and unsafe injections can also prevent hepatitis B virus transmission. Safer sexual practices, including minimizing the number of sexual partners and using barrier protection (condoms), can also prevent transmission. In March 2015, WHO released the first guidelines for the prevention, care and treatment of chronic hepatitis B infection. Among the recommendations are the following: 1) promote the use of simple, non-invasive diagnostic tests to assess the stage of liver disease progression and the appropriateness of treatment; 2) prioritize the treatment of patients with the most advanced liver disease and those at greatest risk of death; and 3) recommend prioritizing the use of nucleoside (acid) analogues that are less likely to develop resistance (tenofovir and entecavir, as well as entecavir in children aged 2-11 years) as both first- and second-line drugs. The above guidelines also recommend lifelong medication for patients with cirrhosis and regular monitoring for disease progression, drug toxicity and early detection of hepatocellular carcinoma. WHO’s response WHO is working on viral hepatitis prevention and control in the following areas: 1) raising awareness and promoting partnerships; 2) developing evidence-based policies and collecting data for action; 3) promoting prevention of transmission through immunization, safe injections, and blood safety; and 4) promoting wider access to hepatitis B surveillance and screening, care, and treatment services. WHO also organizes World Hepatitis Day on 28 July each year to raise awareness and understanding of viral hepatitis.