HEPATITIS B

Public health priority: High for newly acquired cases, routine for unspecified cases.

PHU response time: Investigate confirm newly acquired cases and all other confirmed cases within 3 working days. Enter confirmed newly acquired unspecified cases on NDD with 5 working days.

Case management: Investigate likely source of newly acquired cases.

Contact management: Ensure that contacts of newly acquired cases are offered post-exposure prophylaxis.

Last updated: 06 September 2004

1. Reason for surveillance

• To identify the source of the infection for newly acquired cases, and to prevent further cases

• To monitor the epidemiology of hepatitis B and so inform the development of better prevention strategies.

2. Case Definition

Hepatitis B - Newly Acquired
A confirmed case requires laboratory definitive evidence only.

Laboratory definitive evidence

• Detection of HBsAg in a patient shown to be negative within the last 24 months, or

• Detection of HBsAg and IgM to hepatitis B core antigen, in the absence of prior evidence of HBV infection, or

• Detection of HBV by nucleic acid testing, and IgM to hepatitis B core antigen, in the absence of prior evidence of HBV infection.

Clinical evidence
Not applicable.

Epidemiological evidence
Not applicable.

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.

Laboratory definitive evidence
Detection of HBsAg or HBV by nucleic acid testing, in a patient with no prior evidence of hepatitis B virus infection.

Clinical evidence
Not applicable.

Epidemiological evidence
Not applicable.

Factors to be considered in case identification
Exposure to HBV may result in transient or chronic infection, either of which can be asymptomatic. The infection cannot be reliably distinguished clinically from other forms of hepatitis. Hence it is important to obtain a laboratory diagnosis.

Acute infection is suggested by the presence of anti-HBc IgM in the serum, with or without symptoms. Anti-HBc IgM is present in high titre during acute infection and usually disappears within 6 months. Anti-HBc IgM may also be detectable intermittently in those with chronic infection. HBsAg can be detected in serum from several weeks before the onset of the illness, to days, weeks or months after infection. HBsAg presence alone does not define acute infection.

Chronic carriers can be distinguished by tests which show:

• A positive result for anti-HBc IgG or positive for total anti-HBc, and

• Documentation of HBsAg in two blood samples collected ≥6 months apart.

The presence of HBsAg indicates that the person is likely to be infectious. The presence of HBeAg or hepatitis B DNA is associated with high infectivity.

Summary of serological markers

3. Notification criteria and procedure

Hepatitis B is to be notified by:

• Medical practitioners and hospital CEOs on provisional clinical diagnosis of acute viral hepatitis (ideal reporting by telephone on same day of diagnosis)

• Laboratories on serological confirmation (ideal reporting by routine mail).

Only confirmed cases should be entered onto NDD.

4. The disease

Infectious agent
The hepatitis B virus (HBV).

Mode of transmission
Hepatitis B is usually transmitted by contact with blood, semen or vaginal secretions of an infected (HBsAgpositive) person. Because of the high concentration of virus in blood in some cases, an extremely small inoculum may be sufficient to transmit infection. The virus must be introduced through broken skin, via the placenta or come in contact with mucous membranes for infection to occur.

Well-documented modes of transmission include:

• Sharing contaminated objects that pierce the skin, such as needles, tattoo equipment, body-piercing equipment, acupuncture equipment and razor blades

• Sexual contact (heterosexual or homosexual)

• Perinatal transmission from an infected mother to her infant

• Needlestick injuries

• Contact between infective fluid and mucous membranes, such as a splash of blood into eyes or mouth

• Biting by an infected person

• Transfusion of infected blood or blood products.

Breast feeding does not appear to be a significant route of transmission. Faecal-oral and vector-borne modes of transmission have not been demonstrated.

Under some conditions, HBV can remain viable on environmental surfaces.

Timeline
The typical incubation period is 45 to 180 days, but more commonly 60 to 90 days.

Infectivity commences many weeks before symptom onset and generally persists while HBsAg remains present. Following acute infection, the risk of developing chronic HBV infection varies inversely with age, and is also more likely among the immunocompromised.

Clinical presentation
The usual clinical presentation is characterised by an insidious onset, with anorexia, vague abdominal discomfort, nausea and vomiting, sometimes arthralgias and rash, often progressing to jaundice. The clinical course is indistinguishable from any other types of acute viral hepatitis. Only a small proportion of acute cases are clinically recognised, as only 30-50% of adults and less than 10% of children have symptoms. Infection is usually asymptomatic in infants.

5. Managing single notifications

Response times
Investigation
Within 3 working days of notification by a doctor of a newly acquired case begin follow-up investigation. Unspecified cases are followed up at the discretion of the PHU Director.

Data entry
Within 5 working days of notification enter confirmed newly acquired and confirmed unspecified cases on NDD.

Response procedure (newly acquired cases only)
The response to a notification will normally be carried out in collaboration with the patient's health carers. But regardless of who does the follow-up, PHU staff should ensure that action has been taken to:

• Confirm the onset date and symptoms of the illness

• Confirm results of relevant pathology tests, or recommend the tests be done

• Find out if the case or relevant care-giver has been told what the diagnosis is before beginning the interview

• Seek the doctor's permission to contact the case or relevant care-giver

• Review case and contact management.

Case management
The case management is the responsibility of the treating doctor. PHU staff should assist if requested.

Investigation and treatment
Supportive only during the acute phase. Interferon or combination anti-viral therapy may be of value for some carriers with chronic liver disease.

A repeat test for HBsAg is recommended after 6 months to determine the clearance or continued presence of HBsAg. Those still HBsAg-positive are defined as chronic carriers, and should be counselled accordingly.

Education
The case or relevant care-giver should be informed about the nature of the infection and the mode of transmission. In particular, advice should be given emphasising that blood and other secretions are infectious until they become HBsAg negative, usually within 2 to 3 months. Chronic carriers are usually infectious for life.

Scrupulous attention to standard precautions is important while cases are HBsAg-positive. Surfaces contaminated with blood should be cleaned and properly disinfected.

Objects potentially contaminated with blood (for example razors and toothbrushes) should not be shared with other people and should be kept out of reach of children. Contaminated sharps should be stored in an approved sharps container. Any wound should be covered with an impermeable dressing.

Infected persons (among others) should not share injecting equipment with other people. Disposable needles should only be used once. Infected persons should not donate blood or body parts.

Persons who are HBsAg-positive should be advised that the virus may be transmitted through sexual contact. Patients should be educated to practise abstinence, use condoms, or otherwise practice safe sex. Sex partners who are anti-HBc positive (from previous infection) or anti HBs positive are not at risk for hepatitis B infection (although may be for hepatitis C or D [if a hepatitis B carrier]). Vaccination has an estimated 95 percent efficacy.

Pregnant or sexually active women should be told about the risk of hepatitis B infection to newborns of HBsAgpositive mothers, and of the importance of prophylaxis for such newborns. If an infected woman is pregnant, she should advise her obstetrician or other prenatal care-giver to ensure that hepatitis B immune globulin (HBIG) and hepatitis B vaccine are available for the neonate at the time of delivery.

Parents or guardians of HBsAg-positive persons with intellectual disabilities or behaviour problems should be alerted to the risk of HBV infection associated with aggressive behaviour, such as biting and scratching.

Instruct persons with acute HBV infections to postpone non-emergency dental care and surgery until their viraemia has cleared. HBsAg-positive persons who seek medical or dental care should notify involved personnel of their hepatitis B status.

Exposure investigation (newly acquired cases only)
Determining the source of infection for newly acquired cases may permit identification of other cases and interrupt the transmission. Information regarding exposures during the period six weeks to six months before onset of the illness should be sought. This should include information about:

• Household and sexual contacts with a history of hepatitis or a chronic carrier state

• Sexual contact (heterosexual or homosexual) with multiple sex partners and/or a sex partner who is an injecting drug user

• History of receiving blood transfusions or other blood products, dental or surgical care, renal dialysis or other medical procedures

• History of tattooing, body-piercing or acupuncture

• Use of shared needles

• Needlestick or similar injury

• Accidental exposure of eyes, mucous membranes or a wound to the blood of another person

• Work in high-risk occupational settings such as laboratory, mortuary, ambulance or police work or employment in facilities for the mentally disabled

• Residence in a facility for the mentally disabled

• Any record of incarceration.

Exposure among health care workers should be managed as per circular 2003/39.

Isolation and restriction
The risk of transmission of HBV in the child care setting is usually low, and can be reduced through sound infection control procedures and environmental cleanliness. Toiletry items that could be contaminated with blood or saliva should not be shared. Contaminated objects should be cleaned and disinfected as soon as possible, to prevent transmission. The risk is greatest if the individual is an HBeAg-positive carrier, and/or is a child <3 years old who has open skin lesions, demonstrates aggressive scratching or biting behaviour, or has a bleeding disorder. In child cases, the PHU should carefully assess the situation to determine whether or not exclusion of the child from child care or vaccination of classroom contacts is indicated.

Hospitalised patients with acute or chronic HBV infections pose a minimal risk to staff or other patients, given the implementation of standard precautions, and the appropriate pre-exposure use of hepatitis B vaccine.

Environmental evaluation
Usually none, unless transmission occurs in a child care centre, dialysis centre, or health care facility through infected environmental surfaces or inanimate objects.

Contact management
The management of contacts is usually the responsibility of the treating doctor, but PHU staff should ensure that contacts of newly acquired cases are protected and assist in the follow up of contacts of unspecified cases if requested.

Identification of contacts
Persons with significant opportunity for blood-borne exposure during the infectious period should be identified. The following is a general list of persons considered contacts if exposed to infectious cases:

• All sexual partners

• A newborn child of the case

• All household members and other close contacts who have had an opportunity for blood borne infection to be transmitted.

Treatment
Passive Immunisation
Passive immunisation with HBIG (along with active immunisation with hepatitis B vaccine) is used to prevent infection or modify illness due to infection with HBV. To be effective, HBIG must be given as soon as possible after exposure. The exposed person's prior history of hepatitis B infection, vaccination, and vaccine response status (if known) should always be considered, but treatment should not be unduly delayed whilst awaiting test results.

Post-exposure prophylaxis is recommended in the following situations:

• Perinatal exposure to an HBsAg-positive mother, where HBIG (100 IU IM) should be given within 12 hours of birth, and hepatitis B vaccination commenced

• Percutaneous or permucosal exposure to blood (400 IU for adults, as soon as possible, but <72 hours) and hepatitis B vaccination commenced

• Sexual exposure to an HBsAg-positive individual (if within 2 weeks), where HBIG (400 IU IM) should be given, and hepatitis B vaccination commenced.

HBIG is available by telephoning the Medical Registrar at the NSW Red Cross Blood Transfusion Service.

Active Immunisation
Hepatitis B vaccination is also indicated for persons at increased risk of infection because of lifestyle, medical history, occupation, or ongoing intimate contact with a HBV carrier. Vaccination should be recommended to persons at risk who are identified in the course of a HBV case investigation.

For details, refer to the latest Australian Immunisation Handbook.

In NSW, hepatitis B vaccine is currently available free to:

• All babies

• Contacts of an acute case or hepatitis B carrier, including sexual and household contacts

• All school children aged 10-13 years if they have not been previously vaccinated

• Sexual health clinic clients

• Corrections health service clients.

Antibiotic prophylaxis
None

Education
Advise susceptible contacts (or parents/guardians) of the risk of infection and the need for immunisation; counsel them to watch for signs or symptoms of hepatitis occurring within six months of exposure, and to avoid exposing others to potential infection.

Isolation and restriction
Nil

6. Managing special situations

Cases among health care workers
If the case is a health care worker who performs exposure prone procedures, the case should be assessed and monitored in accordance with NSW Health Department Circular 99/88. HBsAg, HBeAg and/or HBV DNA status must be ascertained before recommencing performance of exposure prone procedures. Other health care workers should be reminded of the need for compliance with standard infection control precautions (Circular 2002/45) and the requirements of their suspected registration boards.

Suspected iatrogenic infection
If more than 1 cases occur among patients of the same dental or health care provider, and circumstances suggest the possibility of iatrogenic infection, initiate an investigation and notify the Communicable Diseases Branch (CDB) immediately.

Cases among health care workers
If the case has donated blood or plasma while infectious, the blood bank and the CDB should be notified immediately.

Cases among health care workers
If transfused blood or blood products are suspected as the possible source of infection, the blood bank and the CDB should be notified immediately.