Hepatitis B
Queensland Health Guidelines for Public Health Units
- Infectious Agent
- Notification Criteria
- Notification Procedure
- Reporting to NOCS
- Objectives of Surveillance
- Public Health Significance and Occurrence
- Clinical Features
- Reservoir
- Mode of Transmission
- Incubation Period
- Period of Communicability
- Susceptibility and Resistance
- Management
- Preventive measures
- Summary
- References
Infectious Agent
The infectious agent is Hepatitis B virus (hepadnavirus - double stranded DNA virus). Hepatitis B virus (HBV) is classified into 8 main genotypes (A-H). There is growing evidence of differences in liver disease severity between HBV genotypes.
Notification Criteria
Laboratory definitive evidence (unspecified hepatitis B)Detection of hepatitis B surface antigen (HBsAg)
OR
Detection of hepatitis B virus by nucleic acid testing, in a patient with no prior evidence of hepatitis B virus infection
Laboratory definitive evidence (newly acquired hepatitis B)
Detection of hepatitis B surface antigen (HBsAg) in a patient shown to be negative within the last 24 months
OR
Detection of HBsAg and IgM to hepatitis B core antigen (anti-HBc IgM), in the absence of prior evidence of hepatitis B virus infection
OR
Detection of hepatitis B virus by nucleic acid testing, and IgM to hepatitis B core antigen (anti-HBc IgM), in the absence of prior evidence of hepatitis B virus infection
Notification Procedure
Pathology Laboratories
To notify on confirmation by usual means.
Reporting to NOCS
Only report confirmed cases.
Hepatitis B (unspecified)
A confirmed case requires laboratory definitive evidence AND that the case does not meet any of the criteria for a newly acquired case.
Hepatitis B (newly acquired)
A confirmed case requires laboratory definitive evidence (newly acquired hepatitis B) only.
NB: The notification criteria outlined above reflect the national case definition for hepatitis B. In Queensland, laboratory notifications of hepatitis B are automatically classified by the Notifiable Conditions System (NOCS) database as 'unspecified' on receipt, and are then automatically converted to 'acute' or 'chronic' under business rules (depending on the availability of relevant laboratory results). 'Chronic' hepatitis B notifications are transmitted to the National Notifiable Diseases Surveillance System under the 'unspecified' category, and 'acute' notifications under the 'newly acquired' category.
Objectives of Surveillance
- To identify cases of acute/newly acquired hepatitis B, so that appropriate public health action can be taken.
- To monitor the epidemiology of hepatitis B.
Public Health Significance and Occurrence
Worldwide; endemic with little seasonal variation. WHO estimates that more than 2 billion people have been infected with HBV and that 350 million have chronic infection. Each year, approximately 600,000 to 1 million people die as a result of infection and there are over 4 million new acute clinical cases.
In countries where pre-transfusion screening of blood is performed, and where pooled blood clotting factors are appropriately processed, the risk of hepatitis B has virtually been eliminated for recipients of blood products. However it is still present in many developing countries. Contaminated and inadequately sterilised syringes and needles have resulted in outbreaks of hepatitis B. Occasionally outbreaks have been traced to tattoo parlours and acupuncturists.
Rarely, transmission to patients from HBsAg positive health care workers has been documented. Outbreaks have been reported among patients in dialysis centres in many countries through failure to adhere to recommended infection control practices.
Death from acute hepatitis B infection is rare, but 15-25% of those with chronic infection may develop cirrhosis and/or hepatocellular carcinoma. Chronic HBV causes most cases of hepatocellular carcinoma worldwide. Only tobacco causes more cancers.
Clinical Features
Less than 10% of children and 30-50% of adults with acute hepatitis B infection show icteric disease. In those with clinical illness, the onset of illness is usually insidious, with anorexia, vague abdominal discomfort, nausea and vomiting, sometimes arthralgia and rash, often progressing to jaundice. Severity ranges from inapparent cases detectable only by abnormal liver function tests to fulminating, fatal cases of acute hepatic necrosis. Fulminant HBV infection also occurs in pregnancy and among newborns of infected mothers.
Chronic hepatitis B is typically asymptomatic, until complications such as advanced cirrhosis, liver failure or hepatocellular carcinoma develop. The risk of developing chronic infection varies inversely with the age when a person becomes infected. More than 90% of infants infected at birth develop chronic infection, compared to 20-50% of children infected between the ages of 1 and 5 years and 10% or fewer of older children and adults. Cirrhosis of the liver, liver failure and/or hepatocellular carcinoma eventually occurs in 15-25% of those chronically infected and premature mortality related to these conditions is significant.
Reservoir
Humans. Chimpanzees are susceptible, but an animal reservoir in nature has not been recognised. Closely related hepadna viruses have been found in woodchucks, ducks, ground squirrels and other animals, such as snow leopards and German herons; but none cause disease in humans.
Mode of Transmission
Body substances capable of transmitting HBV include blood and blood products; saliva (although no outbreaks of HBV infection due to saliva alone have been documented); CSF; peritoneal, pleural, pericardial and synovial fluid; amniotic fluid; semen and vaginal secretions and any other body fluid containing blood; and unfixed tissue and organs. The presence of "e" antigen or HBV-DNA >105 copies/ml indicates a higher viral titre and higher infectivity in these fluids.
Transmission occurs by the following routes:
- percutaneous (IV, IM, SC or intradermal)
- permucosal exposure
- sexual transmission
- perinatal transmission from mother to child
HBV is stable on environmental surfaces for at least 7 days and therefore indirect inoculation can occur via inanimate objects. Faecal-oral or vector borne transmission has not been demonstrated.
In countries where HBV is highly endemic (HBsAg prevalence 8% or higher) most infection occurs in infancy and early childhood. In areas of low prevalence (HBsAg prevalence under 2%) most infections occur in young adults, especially among persons from known risk groups:
- injecting drug users
- people with multiple sexual partners
- men who have sex with men (MSM)
- household contacts and sexual partners of infected people
- health care workers - following blood exposure in the workplace
- prisoners
Shared razors and toothbrushes have been implicated as occasional vehicles of HBV transmission. Household transmission primarily occurs child to child.
Incubation Period
Usually 45 - 180 days, average 60 - 90 days. HBsAg may appear as soon as 2 weeks following infection and rarely as long as 6 - 9 months later. The variation is partly related to the amount of virus in the inoculum, the mode of transmission and host factors.
Period of Communicability
All people who are HBsAg positive are potentially infectious. Blood from infected persons is infective many weeks before the onset of symptoms and remains infective through the acute clinical course of the disease. The infectivity of chronically infected individuals varies from highly infectious (HBeAg positive, HBV-DNA above 105 copies/ml) to modest (anti-HBe positive).
Susceptability and Resistance
Susceptibility is general. Protective immunity follows infection if antibodies to HBsAg (anti-HBs) develop and HBsAg is negative. People with Down syndrome, lymphoproliferative disease, HIV infection, immunosuppression and those on haemodialysis appear more likely to develop chronic infection.
Management
| Cases: | |
| Investigation: | Follow up cases of acute/newly acquired hepatitis B in consultation with the attending medical practitioner. The follow up of all other cases is at the discretion of the public health unit. Identify possible source of infection. If it could be transfusion-related contact the Australian Red Cross Blood Service. |
| Counselling: | The case should be advised of the nature of the infection and its mode of transmission.
|
| Contacts: | |
| Definition | Contacts up to 180 days prior to the index case developing symptoms. If the index case is asymptomatic, according to risk history. Contacts include:
|
| Investigation | Determine if contacts have been immunised or previously infected:
|
| Prophylaxis | Provide hepatitis B vaccine if anti-HBs negative. Hepatitis B vaccine is funded for household and sexual and injecting drug use contacts of people with acute or chronic hepatitis B (full eligibility criteria for vaccine). Hepatitis B immunoglobulin (HBIG) should be given to:
|
| Counselling | Contacts should be advised of the nature of the infection and its mode of transmission. |
Community outbreaks/epidemics
Two or more cases occurring in association with a common exposure warrants a search for additional cases.
Health care settings.
Refer to the following:
- Australian National Guidelines for the Management of Healthcare Workers Living with Blood Borne Viruses and Healthcare Workers who Perform Exposure Prone Procedures at Risk of Exposure to Blood Borne Viruses
- Queensland Health Implementation Standard: Management of Exposure to Blood and Body Fluids
Preventative Measures
- Screening donated blood and tissues
- Standard and transmission based infection control precautions in healthcare settings
- Routine screening of pregnant women
- Hepatitis B vaccination
- Routine vaccination of newborns/infants and unvaccinated adolescents
- Vaccination of those in identified risk groups
- General promotion of safer sex practices and safer injecting drug use practices.
Summary
Prepare a report of any investigation for the Communicable Diseases Branch, Queensland Health, on request.
References
Heymann, D. (Ed). 2008. Control of Communicable Diseases Manual, 19th edition. American Public Health Association: Washington.
Mandell GL, Bennett JE and Dolin R, 2010. Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases, 7th Ed. Churchill Livingstone, Philadelphia.