HIV transmission in the substance misusing population occurs by several routes: parenterally through the sharing of dirty needles or injecting paraphernalia, sexually and by vertical transmission from the infected mother to the foetus or during birth. In the UK, the prevalence of HIV is low when compared with other European countries, and is found largely within Greater London and the South East. The rate in London amongst injecting drug misusers is approximately 1 in 80 for men and 1 in 100 for women. The effectiveness of treatment has improved considerably over recent years due to several factors:
- Combination antiretroviral therapies, including new classes of drug such as the protease inhibitors have been developed and tested.
- Improved methods of viral load determination have been shown to have prognostic value.
- Improvements in opportunistic infection prophylaxis strategies and treatments now prolong disease-free states.
- Zidovudine for HIV-infected pregnant women has been shown to decrease vertical transmission.
- Prophylaxis for needle-stick injuries now decreases transmission in health care settings.
Treatment will now commonly commence with combination therapy which decreases viral load and may delay viral drug resistance (which is increasingly a major concern). In November 1994, Connor et al reported that the administration of zidovudine to previously untreated HIV-infected pregnant women and their newborns reduced the rate of perinatal HIV infection by two-thirds from one in four to one in twelve. It is now recommended that all pregnant women be offered HIV testing and counselling; this is especially important in those with a history of illicit substance misuse.
TESTING
Whilst in general injecting drug misusers should be encouraged to have testing (in view of the effectiveness of treatments now available), this must always remain the client's decision, and should always be preceded by the giving of informed consent. There are various issues which should be discussed before testing in order that the patient makes an informed decision before proceeding:
- The likelihood of a positive test result.
- The potential social and financial implications of a positive result.
- The patient's understanding of what a positive test means medically.
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- Pre- and post-test counselling should be offered and informed consent obtained before testing for HIV and hepatitis viruses.
- In the UK, the prevalence of HIV is low when compared with other European countries. HIV is found largely within Greater London and the South East, where prevalence is in the region of 1% amongst injecting drug misusers. It is now recommended that all pregnant women be offered HIV testing, as the risk of vertical transmission (infection of the baby) is much reduced by administration of medication. Treatment for HIV infection is increasingly effective.
- In the UK, recent evidence suggests that between 50 and 80% of past and current injecting drug users may be infected with hepatitis C. Treatment is only appropriate in selected cases, but all hepatitis C positive patients may benefit from advice to cease alcohol consumption and regarding avoidance of onward transmission.
- Vaccination against hepatitis A & B should be offered to all drug users and to the close contacts of those who are carriers of the hepatitis B virus.
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- What supports are available to him or her.
- Results should ideally be given by the person who organised the test, as a planned consultation on a definite day.
- Patients with positive results will need clear advice about onward medical treatment and referral.
Sometimes, an HIV test is requested immediately after an episode of high risk behaviour, such as needle sharing, and the patient needs to be advised that testing will not provide a reliable result until sufficient time has elapsed for the development of antibodies.A wait of three months between the last episode of risk-taking and the performing of the test is advisable, providing accurate results in 99% of all cases. If a test result is negative, reassure and advise about minimising future risk-taking. If a test result is positive, offer appropriate support, advise about how to avoid transmission to others, and offer referral for treatment. After learning of the diagnosis the drug user may require considerably more support than previously.
Next page .. VIRAL HEPATITIS
The above information is copyright of Dr Bruce Trathen MBBS MRCPsych (2006). ISBN 0-9545164-0-0. The author grants permission for these guidelines to be downloaded, copied and distributed freely, but does not grant permission for their sale.
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