VHPB recommendations on surveillance of hepatitis B (July 1997)

Source : Viral Hepatitis vol 5.3 (see publications)

Surveillance is necessary to determine the incidence, prevalence and burden of a disease. The success of any surveillance system is dependent on the willingness of doctors to report cases of infectious disease. Feedback to reporting physicians is an integral part of any surveillance system. The role and purpose of surveillance should be stressed from the start of medical training.

Surveillance systems for hepatitis B are necessary to:

  • prioritise hepatitis B among other diseases of public health importance;
  • measure the impact of vaccination programmes (including the monitoring of adverse effects);
  • evaluate prevention programmes;
  • ensure that targets for disease reduction and prevention are met.

Surveillance may also alert health officials to outbreaks of disease.

In most European countries notification of acute hepatitis is mandatory, but wide differences between case definitions, and the completeness and methods of reporting exist, making it extremely difficult to draw meaningful conclusions from country-to-country comparisons.

For better standardisation of surveillance systems across Europe, the VHPB recommend greater uniformity in formulating case definitions, in submitting surveillance reports, in monitoring vaccine coverage and impact, and in reporting severe adverse events.

1. Formulating case definitions

The VHPB recommend that all countries formulate a case definition, and support the case definition of viral hepatitis B put forward by the World Health Organisation:

  • A clinical case of acute viral hepatitis is an acute illness that includes the discrete onset of symptoms and jaundice or elevated serum aminotransferase levels (> 2.5 times the upper limit of normal).
  • A confirmed case of hepatitis B is a suspected case that is laboratory confirmed: HBsAg positive or anti-HBc-IgM positive, and anti-HAV-IgM negative.

The serological quality of the tests used is crucial for a firm diagnosis of infection. It is understood, however, that case definitions based on serological tests pose a problem for countries without widespread access to these tests. Methods to detect HBsAg using test procedures such as reverse passive hemagglutination (RPHA) or latex bead technology are very inexpensive, and while not as sensitive as radioimmunoassay (RIA) antigen tests or the enzyme-linked immunosorbent assay (ELISA), are far better than not testing at all.

2. Submitting surveillance reports

Regardless of the availability of serological tests, all countries are advised to report all cases of jaundice and suspected viral hepatitis. Countries with laboratory facilities can further differentiate between hepatitis A, B, C and other types of hepatitis. Surveillance reports should be submitted on a regular basis, and at a minimum, once a month.

Data from acute disease reporting systems underestimate the true incidence of hepatitis B virus infection in the community because:

  • at least 60 percent of infections in adolescents and adults are asymptomatic or subclinical;
  • a high degree of underreporting takes place;
  • 90% or more of infections occurring in infants and children are asymptomatic and are therefore not reflected in the reported data.

Although surveillance of acute disease can be an essential parameter, it is insufficient to give a clear picture of the burden of disease. Surveillance of the chronic consequences of HBV (for instance, cirrhosis and HCC) and reporting of disease-specific mortality data is useful to document the burden of disease in the community. Acute case notification should be followed up by further epidemiological investigation and implementation of appropriate control measures. All outbreaks should be investigated immediately and confirmed serologically.

Outbreak investigation and sentinel surveillance may serve as supplementary sources of data on disease surveillance. In addition, sero-surveillance systems are very cost-effective ways of looking at the epidemiological situation of an infectious disease.

Although screening of blood donors is a very efficient system for preventing transmission of bloodborne pathogens, prevalence data from blood donors are not representative of the general population. Certain population groups - such as pregnant women and military personnel - are easily accessible for hepatitis screening, and data collected from these groups are relevant and should be incorporated into surveillance systems. In addition, hospital diagnosis systems should also be considered as additional sources of information.

3. Monitoring vaccine coverage and impact

All countries should have coverage assessment systems in place for the vaccine-preventable diseases included in the national immunisation schedule. The target age for assessing vaccine coverage is dependent on the chosen vaccination programme and should be clearly defined.

The impact of vaccination programmes on acute and chronic disease cannot be measured until many years after implementation. However, countries may decide to conduct serological studies to measure the effectiveness of the vaccination programme: taking serological assessment of markers such as surface antigen and core antibody can document a reduction in chronic carrier rates and acute disease.

4. Reporting severe adverse events

Adverse events monitoring systems are already in place for tracking adverse events following immunisation; these guidelines should be applied to hepatitis B immunisation programmes.