Quiz feedback: Hepatitis

GP panel:

It is clear that most people are aware which of the above are risk factors for hepatitis A. The panel was curious as to why IV drug use is a risk factor, when it is known transmission of hepatitis A is by the faecal-oral route. It was suggested there may be increased risk because the living conditions for many IV drug users may be substandard (with overcrowding and poor personal hygiene) and associated with increased exposure to faecal contamination. Perinatal transmission of hepatitis A is rare. If the mother develops symptoms two weeks before to one week after delivery, the infant may be given IG (0.02 mL/kg), although its efficacy in these circumstances has not been established.

Specialist comment:

The most common reported source of infection is household or other close contact with an infected person. Outbreaks of hepatitis A infection among injecting drug users have been reported in North America and Scandinavia. Several routes of transmission are likely to occur including a combination of person-to-person and percutaneous spread. Poor personal hygiene among drug users may be a source of hepatitis A contamination of drugs or drug paraphernalia, as well as direct person-to-person transmission. Viraemia occurs within 1–2 weeks after hepatitis A exposure and persists through the period of liver enzyme elevation. Virus concentration in serum is 2–3 log₁₀ units lower than in stool. Percutaneous transmission of hepatitis A by needle sharing can occur. Faecal contamination of drugs by rectal transportation has been reported but is probably a rare source of infection.

GP panel:

Again, these responses demonstrate that GPs are very clear about risk factors for hepatitis B infection.

There were mixed responses to whether a blood transfusion is a risk factor of hepatitis B. It was acknowledged that some people would be chronically infected from receiving infected blood prior to routine blood screening in New Zealand. Following the implementation of blood screening for hepatitis B in New Zealand in 1971, the risk of contracting hepatitis B through a blood transfusion in New Zealand, is now considered extremely low.

Specialist comment:

In the United States, the risk of post-transfusion hepatitis B is estimated to be one to four per million blood component transfused. In endemic countries the risk may be higher, although nucleic acid testing aims to reduce this and has been introduced in some countries.

GP panel:

The panel discussed the uncertainty that currently exists about how infective Hepatitis C is, particularly in relation to sexual activity. The panel commented they had known of situations when an individual had hepatitis C, but their sexual partner had continued to remain negative for many years.

This led on to a discussion about the likelihood of an increased theoretical risk of transmission from a newly infected person who hadn’t yet developed symptoms, ie still in the ‘window period’.

Specialist comment:

Successful antiviral therapy may remove the possibility of transmission to partners. Sexual transmission of hepatitis C occurs at a low rate (<1% per year of relationship or about 2% of partners in long-term relationships). These rates increase if the index case is also HIV infected.

Most patients (>60%) do not have symptomatic acute infection. This means many infections are only detected by screening asymptomatic patients at increased risk of infection. HCV RNA is detectable about 2 weeks after infection whereas the appearance of anti-HCV takes 8–9 weeks. For the minority who experience symptoms, these occur around 6–8 weeks after infection.

Vertical (mother to infant) spread also occurs at a low rate (2– 5%). Higher rates are seen if there is HIV co-infection.

GP panel:

It was clear from the responses that GPs are very aware that Hepatitis A does not develop into a chronic hepatitis. This lead on to a discussion, as to whether there are any long term health issues as a result of hepatitis A.

Specialist comment:

Hepatitis A is rarely complicated by extrahepatic manifestations or fulminant hepatitis. However, the expectation is that patients will recover without sequelae.

GP panel:

The panel discussed the scenario of the patient who requests confirmation/reassurance that the vaccine “has worked”. They agreed that it would be a situation to discuss the current recommendations that post vaccination immunity check for hepatitis B is not routinely indicated. However ultimately the patient makes an informed choice.

The panel found it helpful to be reminded of the practice in NZ whereby pregnant women are offered a blood test to see if they are chronic carriers of hepatitis B. Babies born to infectious mothers are immunised soon after birth with Hepatitis B vaccine and immunoglobulin, then receive the national immunisation schedule vaccines at the usual times. At 5 months a blood test is taken to check for seroconversion/antibody levels. If the anti-HBs measurement is less than 10 mIU/mL the baby should be given further doses of vaccine at 6 & 7 months with a repeat blood test at 8 months of age.

Specialist comment:

Infants born to hepatitis B infected mothers should be tested at around 5 months for both HBsAg and anti-HBs. In addition to measuring antibody response to vaccine, this is to identify the approx 5% of infants that are hepatitis B infected (and therefore will likely have chronic infection) despite immunoprophylaxis. With appropriate immunoprophylaxis, breast-feeding of infants poses no additional risk for the transmission of hepatitis B.

GP panel:

The panel were in agreement about the tests to be done to help diagnose the cause of an acute hepatitis but voiced that it might tempting to order a Hepatitis C antibody test for completeness sake even if someone was not a drug user. Although it is worth remembering that the majority of patients with newly acquired hepatitis C will be asymptomatic.

While it is preferable to carefully choose the tests based on the clinical scenario, this can be difficult in practice. In addition the combination of tests is often predefined in the PMS system or on the laboratory form. It is useful to provide clinical details on the laboratory requisition form, as this can help the laboratory with appropriate test choices.

Specialist comment:

No further comment

GP panel:

The panel were in agreement that pre-immunisation screening is indicated for those at higher risk of being a hepatitis B carrier. They acknowledged this may include those infected as a child, since approximately 90% of infected infants and 25–50% of infected children aged 1-5 years will remain chronically infected.

The panel were unsure what the risks would be if an immune person or hepatitis B carrier was inadvertently vaccinated for hepatitis B. They were also interested about what further vaccinations were required for someone who had started or partially completed a hepatitis B vaccination course but never finished it.

Specialist comment:

The role of pre-vaccination screening is to identify individuals who do not require vaccination and to reduce unnecessary vaccination. The need for pre-vaccination screening should be guided by the likelihood that an individual has been exposed to hepatitis B. For high risk groups, this may be an opportunity to identify a chronically infected patient who may benefit from ongoing surveillance and treatment. The administration of hepatitis B vaccine to individuals who are infected or immune will not result in any adverse outcome.

Longer than recommended intervals between doses do not reduce final antibody concentrations. An interruption in the vaccination schedule does not require restarting the entire series of vaccination or adding extra doses. If the vaccination series is interrupted after the first dose, the second dose should be administered as soon as possible. The second and third doses should be separated by an interval of at least two months. If only the third dose is delayed, it should be administered when convenient.

GP panel:

The panel agreed that for the vast majority of people travelling to a country with high risk of hepatitis A vaccination without prior screening was indicated. In this scenario the panel advocated use of a hepatitis A vaccine (sometimes used in combination with other vaccines such as Hepatyrix or Twinrix) and then another booster within 6 months if the patient wants to maximize duration of future cover.

Specialist comment:

Agree, most people do not require pre-travel screening.

Pre-vaccination antibody screening (Hepatitis A IgG antibody) is only justified in older travellers, those who have lived in areas where hepatitis A is endemic (average prevalence of immunity of over 30 percent), or those with a history of jaundice.