NAME: Hepatitis B virus (HBV).
SYNONYM OR CROSS REFERENCE: HBV Footnote 1-Footnote 11, hepatitis B Footnote 1, HBV infection Footnote 1-Footnote 3, Footnote 11, type B hepatitis Footnote 4, Footnote 12, Footnote 13, serum hepatitis, homologous serum jaundice, Australia antigen hepatitis, and HB Footnote 4.
CHARACTERISTICS: HBV is a member of the Hepadnaviridae family Footnote 1, Footnote 11, has a circular DNA genome that is partially double stranded and partly single stranded, and is 42 nm in diameter Footnote 1, Footnote 2, Footnote 4. HBV is comprised of a number of clinically important viral proteins, including the envelope protein, hepatitis B surface antigen (HBsAg), hepatitis B core antigen (HBcAg), and a soluble nucleocapsid protein, the hepatitis B e antigen (HBeAg) Footnote 3.
Eight genotypes of HBV have been identified (A to H) Footnote 2-Footnote 4, Footnote 10, Footnote 14, Footnote 15, that show differential geographical distributions Footnote 2, Footnote 14 and clinical outcomes Footnote 14. For example, genotypes B and C are prevalent in Asia Footnote 2, Footnote 14, while A and D are more common in Europe, the Middle East, and India Footnote 2, and A and C are the most common in North America Footnote 14.
PATHOGENICITY/TOXICITY: Acute hepatitis B infection: Persons with acute hepatitis B infection may be asymptomatic or present with a clinical picture varying from mild to severe hepatitis Footnote 2. Persons with symptomatic acute HBV infections can show signs and symptoms that include nausea, abdominal pain, vomiting, fever, jaundice, dark urine, changes in stool colour, and hepatomegaly or splenomegaly as well as signs of liver dysfunction Footnote 1, Footnote 2, Footnote 11. The outcome of acute HBV infection is usually good with complete recovery from any liver damage and seroconversion to anti-HBs, which represents a long-term protection from HBV infection Footnote 2.
Chronic hepatitis B infection: Defined as the persistence of HBsAg for more than 6 months Footnote 1, Footnote 2, Footnote 6, Footnote 11. Persons with chronic HBV infection may be asymptomatic or may suffer from symptoms such as fatigue, anorexia, nausea, abdominal discomfort and liver dysfunction. They are at substantially increased risk for developing chronic liver diseases, including cirrhosis of the liver and primary hepatocellular carcinoma Footnote 11.
EPIDEMIOLOGY: HBV infection is a worldwide health problem Footnote 2, Footnote 4, Footnote 5. Two billion people worldwide have been infected with HBV, 360 million have chronic HBV infection and 600,000 die each year from HBV-related liver diseases or hepatocellular carcinoma Footnote 1, Footnote 4. HBV infection is most prevalent in Asia, Africa, Southern Europe and Latin America where the prevalence of HBsAg carriers in the general population ranges from 2-20 % Footnote 2. In these areas, HBV infection mainly occurs in childhood and early infancy. North America, Northern Europe, and the Oceanic region are low prevalence areas, where HBV infection typically occurs in adolescence and early adulthood.
HOST RANGE: Humans are the only known natural host Footnote 1-Footnote 7, Footnote 9, Footnote 11, Footnote 13. Chimpanzees are susceptible as an experimental animal Footnote 4, Footnote 9, Footnote 11, Footnote 12, Footnote 16.
INFECTIOUS DOSE: Unknown.
MODE OF TRANSMISSION: HBV is transmitted by percutaneous or mucosal exposure to infected blood or other body fluid Footnote 1, Footnote 3, Footnote 4, Footnote 11. HBV transmission has been observed with numerous forms of human contact such as perinatal/mother to child, household (non sexual), sexual, needle sharing, and occupational/health-care-related Footnote 1, Footnote 4, Footnote 11.
INCUBATION PERIOD: Usually 24-180 days (average 60-90 days) Footnote 2, Footnote 4. The variation depends on the amount of virus in the inoculum, mode of transmission, and other host factors Footnote 4.
COMMUNICABILITY: All persons who are HBsAg positive are potentially infectious, and blood can be infectious for several weeks before the onset of clinical symptoms Footnote 4.
RESERVOIR: Humans Footnote 1.
DRUG SUSCEPTIBILITY: Sensitive to antivirals such as interferon-α, pegylated interferon α-2a, lamivudine, adefovir, entecavir, telbivudine, and tenofovir Footnote 3.
SUSCEPTIBILITY TO DISINFECTANTS: Treatment of HBV diluted in phosphate buffered saline with 1% non-ionic detergent (Triton X-100) plus 0.3% tri-n-butyl-phosphate leads to HBV inactivation Footnote 7. HBV is also inactivated by formaldehyde, glutaraldehyde, sodium hypochlorite (5,000 ppm available chlorine), quaternary ammonium compounds, and alcohols (70-80%) Footnote 8.
PHYSICAL INACTIVATION: Moist heat at 98°C for 1 minute will partially inactivate HBV in a 1:10 serum dilution Footnote 13. Incubation at 60°C for 10 hours (pasteurisation) will also inactivate HVB Footnote 7.
SURVIVAL OUTSIDE HOST: HBV can survive and remain infectious on environmental surfaces for at least 7 days Footnote 17.
SURVEILLANCE: Monitor for symptoms. Demonstration in sera of specific HB antigens and/or antibodies (HBsAg, anti-HBs, HBeAg, anti-HBe, and anti-HBc) using enzyme immunoassay techniques (e.g. ELISA) confirm diagnosis Footnote 15. Other tests include radioimmunoassay Footnote 12, PCR Footnote 2, Footnote 6, real-time PCR, and non-PCR based DNA assays Footnote 6.
Note: All diagnostic methods are not necessarily available in all countries.
FIRST AID/TREATMENT: Following exposure to HBV the affected area should be washed immediately with soap and water. Mucous membranes and conjunctivae should be irrigated thoroughly with water Footnote 10. If the material involved is known to contain HBV or be positive for HBsAg then hepatitis B immunoglobulin (HBIG) should be given, ideally within 48 hours of exposure Footnote 18.
Seven drugs are licensed in the United States for treatment of HBV infection: interferon-α, pegylated interferon α-2a, lamivudine, adefovir, entecavir, telbivudine, and tenofovir Footnote 3.
IMMUNISATION: Two types of HB vaccine have been licensed and shown to be highly effective against all subtypes of HBV Footnote 4, Footnote 11. The first, prepared from plasma from HBsAg-positive persons, is still widely used. The second is synthesised using recombinant DNA Footnote 4. Vaccination against HBV should now be the norm in laboratory personnel Footnote 10.
PROPHYLAXIS: Previously unimmunised adults exposed to HBsAg positive blood should receive HBIG as soon as possible as well as immunization with HB vaccine unless natural immunity can be confirmed Footnote 4, Footnote 10.
LABORATORY-ACQUIRED INFECTIONS: The rates of HBV infection have been reported to be several times greater in laboratory staff than the general population and is one of the most frequently reported laboratory acquired infection Footnote 10.
SOURCES/SPECIMENS: Blood Footnote 1-Footnote 12, cerebrospinal fluid, saliva, semen, synovial fluid Footnote 4, Footnote 12, breast milk, bile, faeces, nasopharyngeal washings, sweat Footnote 12, peritoneal, pleural, pericardial, amniotic, and unfixed tissues and organs Footnote 4.
PRIMARY HAZARDS: Percutaneous (e.g. needlestick) or mucous membrane exposures to blood that might contain HBsAg Footnote 4.
SPECIAL HAZARDS: There is a potential for infection via aerosols and HBV contaminated surfaces Footnote 10.
RISK GROUP CLASSIFICATION: Risk Group 2 Footnote 19.
CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infectious or potentially infectious material, animals, or cultures.
PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable. Eye protection must be used where there is a known or potential risk of exposure to splashes Footnote 20.
OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC). The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities Footnote 20.
SPILLS: Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply an appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up Footnote 20.
DISPOSAL: Decontaminate all wastes that contain or have come in contact with the infectious organism by autoclave, chemical disinfection, gamma irradiation, or incineration before disposing Footnote 20.
STORAGE: The infectious agent should be stored in leak-proof containers that are appropriately labeled Footnote 20.
REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.
UPDATED: December 2011
PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada.
Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.
Public Health Agency of Canada, 2011