Principles for control of HCV infection and associated disease (July 1995)
Source : Viral Hepatitis vol 4.1 (see publications)
Given the limited effectiveness of current treatments, major efforts to prevent HCV infection within the population are required. The principal components of a control strategy for HCV infection and associated disease are:
- measures to establish adequate public health and information systems addressing occurrence, distribution and costs of the infection, and trends in these over time;
- measures to interrupt transmission;
- measures to counsel and control disease in those already infected;
- further research.
Establishing public health and clinical information systems
Public Health authorities need urgently to review current systems were these exist and to make plans for their establishment or development. Such systems should be designed to allow:
- targeting of interventions;
- monitoring of the occurrence and trends of infection;
- monitoring of the uptake of treatment, and coverage of interventions;
- assessment of the effectiveness of previous treatments and of intervention programmes.
Interrupting transmission
The immediate priorities are defined by the predominant modes of transmission described above.
Prevention of parenteral transmission
Maintain and monitor the protection of the blood supply and other tissues used for medical procedures and dialysis equipment. Currently, effective serological assays are available to prevent HCV transmission from blood, blood products and other human tissues. However these tests cost more than $ 5.00 per test and are unaffordable for some developing countries and transitional economies.
This will require:
- the development of cheap screening tests and the implementation of affordable screening programmes in blood banks of all countries. This will require negotiations with manufacturers.
- continuation or institution of screening of all donors of tissue products or the products themselves for the presence of HCV using modern sensitive tests. Appropriate quality control systems must constitute an integral part of such screening programmes.
- continuation or institution of policies of self exclusion from blood and tissue donation.
- the use of viral inactivation treatments for blood and tissue products where feasible and appropriate.
Prevent transmission to health care workers through occupational parenteral exposure
The adoption by health care workers of universal precautions developed to prevent other blood-borne diseases should be a major priority. To achieve this will require:
- raising the awareness of the occupational risks of infection through appropriate staff training;
- recognition of clinical settings and clinical groups in which a high prevalence of infection may be expected, and institution of appropriate infection control procedures by clinical and laboratory staff against HCV transmission.
Prevent transmission through injecting drug use
This will require programmes comprising:
- preventive efforts aimed at reducing the number of new and established injecting drug users;
- preventive efforts aimed at early harm reduction through reducing injection associated behaviours likely to carry risk of transmitting the infection.
These should include:
- provision of information and education (e.g. early prevention in schools) promoting the avoidance of drug use and, in particular, injecting drug use;
- access to disposable sterile injecting equipment and promotion of disposal (needle exchange programmes);
- promotion of hygiene in preparation of injectable drugs and discouraging the sharing of injecting equipment.
It is crucial that such measures should be fully integrated with and build upon the experience of programmes for the prevention of HIV transmission through injecting drug use.
Prevention of vertical transmission
The risk of vertical transmission appears to be low, and at present no effective pharmacological, immunological or behavioural means are available to control transmission of infection from an infected mother to her child. In these circumstances there would not appear to be any obvious benefit to the child in routine screening of pregnant women for HCV infection. Pregnancies among HCV-positive women should not be discouraged.
Other modes of transmission
Sexual transmission
This may require measures focused both on individuals who are known to be HCV infected or who are at high risk of infection and on the population at large.
Individuals HCV infected or at high risks
Counselling should be offered to such individuals which fully informs them of currently available information about the risks of sexual transmission of the virus and which promotes safer sex practice. Individuals should be supported in making their own decisions about appropriate safer sex strategies (including condom use) to reduce their risk of transmitting infection to others, in the context of their particular circumstances.
General population
Current measures to promote safer sex strategies for the prevention control of HIV transmission should continue to be supported.
Transmission to household contacts by individuals who are HCV infected or at high risk
Such individuals should be fully informed of currently available information about the low risk of this mode of transmission of the virus. General precautions in terms of not sharing tooth brushes, razors and avoid contact with bleeding wounds should be encouraged.
Measures to counsel and control disease in those already infected
As described in the previous section the majority of individuals who are infected with HCV are likely to be unaware of both their infection and potential infectiousness. Thus there are two distinct groups who could benefit from such measures:
- Individuals already known to be HCV infected;
- Individuals who are HCV infected but in whom this is unknown.
The following issues need to be considered and kept under continuous review:
- Is therapy of known HCV infected individuals using currently available modalities justified clinically?
Three groups of patients should be distinguished: (1) those with symptomatic infection, (2) those with asymptomatic infection with elevated liver enzymes, and (3) those with asymptomatic infection with normal liver enzymes. Insufficient information is currently available to provide a definitive answer to this question, concerning these three groups. Further studies of the longer term clinical effectiveness of different modalities are needed. At present it is recommended that treatment should be offered according to clinical indication by centres with appropriate experience and expertise, where appropriate treatment should be carried out in the context of properly designed therapeutic trials with follow-up periods of adequate duration.
- Is the identification of unknown HCV infected individuals within the community justified by the possibility both of preventing serious complications of infection, and controlling further transmission?
Given the need for better information concerning the therapeutic effectiveness and natural history of HCV infection, it is difficult to justify systematic screening programmes for individuals who may be identified as being at high risks of being infected. On the other hand, clinicians should be aware that if such individuals present with symptoms, HCV testing may be indicated, and that HCV infection should be included in the differential diagnosis as part of good clinical practice. Such individuals may include injecting drug users, people who have received blood products or transfusions prior to the introduction of HCV antibody screening, people who have had renal dialysis, and households and sexual contacts of known HCV infected individuals.
Priorities for research
Priorities for such research should be to:
- develop cheaper, simpler, but highly sensitive and specific tests for HCV infection;
- describe the distribution of prevalent and incident HCV infections in the wider community by geography, social, demographic and behavioural features and presumptive mode of acquisition of infection. Where possible a subset of this information should be strain type specific;
- describe the historical evolution of the epidemic over time in both blood transfusion recipients and injecting drug users;
- define the natural history of the infection in patients acquiring infection by different routes, and the host and viral determinants of this;
- further establish risks of vertical transmission and its determinants;
- elucidate the mechanisms and efficiency of transmission of infection through apparently non parenteral routes;
- better establish prevalence, risks and control strategies for occupationally acquired and nosocomial infection;
- develop models of the transmission dynamics of HCV infection in different populations and the empirical estimation of the important transmission factors;
- identify the clinical and consequent economic benefits of therapeutic interventions over adequate follow-up periods, and the virological and host correlates of successful therapy. Studies in injecting drug users are urgently required;
- Identify the epidemiological and consequent economic benefits of therapeutic interventions, secured through a reduction in the infectivity of affected individuals.
