2 Background

2.1 To refer to `AIDS and drug misusers' can be to adopt a useful short-hand but it should not obscure the facts that:

i. a wide and heterogeneous group of people may have become infected with HIV through injecting drug misuse, or may misuse illicit drugs and have become infected through sexual behaviour.

ii. HIV-infection and drug misuse together may result in a diverse spectrum of conditions affecting both physical and mental health.

2.2 If agencies are to respond appropriately to the needs of individuals, then it is important to understand some of the distinctions implicit in the use of more general terms.' In this chapter we describe the range of patterns of drug misuse and the ways in which people with HIV-infection may be, or have been, involved in drug misuse; provide a brief description of the nature of HIV-infection and its sequelae of HIV-disease including AIDS; define some of the terms which we will go on to use throughout the report; and comment on what is known about the extent of HIV-infection among drug misusers.

Drug Misusers

2.3 There will be a range of people who may have acquired HIV-infection in connection with their drug misuse. First, there are those who might have been infected through injecting drug misuse but who are now drug free. People who experimented with drugs in the past but never became regular users fall into this category. So do people who were regular drug misusers but who have been
' In this report we have for convenience used the term `drug misuse' to embrace the concept of `problem drug use' as defined in the ACMD's Treatment and Rehabilitation Report (1982) and expanded in its Report, AIDS and Drug Misuse Part 1 (1988). abstinent for a long time and have acquired new networks of non-drug misusing friends. Such people are unlikely to identify themselves as drug misusers and will not be in contact with nor desire links with specialist drug services.

2.4 Secondly, there are people who have recently stopped misusing drugs after a period of drug dependency. Some will never have been in contact with helping services. Others will have received treatment to achieve and sustain abstinence but no longer wish to retain contact with drug services. For some drug misusers who have recently become abstinent, the discovery that they are infected with HIV may precipitate a return to drug misuse. For others, cessation of drug misuse may be followed by increased sexual activity or use of alcohol, or both, and this behaviour may not necessarily be curbed when they learn they are seropositive.

2.5 Thirdly, there are those who are currently misusing drugs by injection. Patterns of drug use, and methods of administration, vary considerably over time between and within different areas and this group is by no means homogeneous. It includes both casual and regular injectors who may be injecting opiates, amphetamine, cocaine, other pharmaceutical preparations such as benzodiazepines and barbiturates, or a combination of whatever drugs are most readily available. Some of these people will be in contact with helping agencies, but the majority will not. Some — particularly experimental or infrequent injectors of non-opiates — may not consider themselves as `drug misusers' and may not perceive themselves as at risk of HIV-infection.

2.6 In addition to the risk of acquiring HIV-infection through sharing injection equipment, drug misusers, like the rest of the population, can acquire the disease sexually. They may be particularly at risk from drug-using partners. There is evidence that drug misusers who do not inject have acquired HIV-infection sexually, and that some patterns and types of drug use may be associated with the likelihood of high-risk sexual behaviour. This will include regular prostitutes who misuse drugs, and drug misusers who engage in occasional male or female prostitution for money to purchase drugs, or who exchange sex for drugs, shelter or other support. It will also include those whose sexual behaviour and ability to use (or not use) appropriate safer sexual techniques will be influenced by their concomitant use of drugs, including alcohol.

2.7 It is apparent that service providers must recognise the different needs not only of those people who are curently injecting drugs, but also those who became infected through past drug misuse, and those who currently misuse drugs by whatever route who may have acquired HIV-infection through sexual behaviour.

HIV-Infection and AIDS Antibody Tests

2.8 The diagnosis of HIV-infection depends on the detection of antibodies (anti-HIV) which indicate infection with the virus. Anti-HIV usually appears within 4 to 16 weeks, although it sometimes takes longer. Until anti-HIV appears therefore, some infected people will be antibody negative. Several tests are needed to ensure the accuracy of the result. The person with anti-HIV is described as seropositive. Conversely, a seronegative person has no detectable antibodies and is probably not infected, but recent infection can not be excluded.

Antigen Tests

2.9 Antigen is a component of the virus itself, and its presence correlates with infectiousness. After infection, antigen appears before anti-HIV and then becomes undetectable. Its reappearance often heralds progression to AIDS. It is therefore thought that people are highly infectious when they first become infected, then are less infectious until they are about to become ill. Other sensitive tests for the virus are likely to be available shortly.

The Spectrum of HIV-Disease

2.10 Although we recognise that HIV-infection cannot accurately be described as a disease, in this report for reasons of convenience we use the generic term "HIV-disease" to cover the full range of HIV-related conditions from infection to AIDS.

2.11 HIV causes immune deficiency because it infects the population of T4 or helper lymphocytes. These white blood cells co-ordinate the immune response and are important in protecting against infections with parasites, viruses, fungi and bacteria, and against cancer. A weakened immune system leaves the body open to such life-threatening "opportunistic" infections and cancers. Many seropositive injecting drug misusers are afflicted by serious infections due to more virulent micro-organisms which, because thay are not "opportunistic", cannot be classified as AIDS yet may cause deaths which are due to HIV-disease.

2.12 As time passes, the heterogeneity of HIV-disease becomes more apparent leading to increasing use of the newer CDC (Centres for Disease Control, Atlanta) classification rather than the traditional classification based on AIDS diagnoses. This classification is comprehensive yet flexible and better mirrors the widening clinical spectrum. It divides infection into 4 groups which reflect both the stage and the severity of disease. Another classification system, the Walter Reed system is also useful for clinicians to `stage' deterioration. Common to all 3 systems is the concept of a long but variable incubation period during which the disease process may develop. Initially this is often insidious and covert, but it leads subsequently often to a series of more disabling illnesses, until the terminal deterioriation. We will now review briefly the progression of HIV infection with reference to the CDC classification groups.

CDC Group

I    Acute infection
II Asymptomatic infection
III Persistent generalised lymphadenopathy
IV Other (more significant) disease:

Subgroup (of Group IV)

A Constititional (prolonged fevers, marked weight loss)
B    Neurological (dementia, neuropathy)
C Secondary infectious disease
C 1 — as defined for AIDS
C2 — others (eg tuberculosis, oral thrush etc)
D    Secondary cancers
E    Other conditions (eg immune thrombocytopenic purpura)

CDC Group I — Acute Infection
2.13 A glandular fever type illness with fever, lymphadenopathy and rash — may follow within a few weeks of infection although most individuals probably sero-convert without symptoms. There have also been a few reports of transient meningitis, neuropathy or myopathy coincident with sero-conversion.

CDC Group II — Asymptomatic Infection
2.14 After infection the infected person usually shows no clinical features of disease, and is described as asymptomatic. Measurements of immunological function may — or may not — be completely normal. The mean time between infection and the onset of AIDS is now estimated at 8 years but with wide variation. It is not yet known if one can be infected for life without developing AIDS. Various studies show about 30 to 40% are likely to progress to AIDS after 5 to 7 years. An additional 25 to 40% will develop other less severe illnesses, but which will have an adverse prognosis. Over time, it is likely that the majority of those infected will progress to AIDS.

CDC Group III — Persistent Generalised Lymphadenopathy
2.15 Generalised lymphadenopathy (PGL) is common with lymph nodes persistently enlarged in the neck or armpits. It needs to be distinguished from other causes commonly found in drug-misusers especially those due to the injecting habit.

CDC Group IV — Other (more significant) disease
2.16 Group IV describes the chronic and more severe expressions of HIV disease including the many manifestations of AIDS. People with the constitutional upset of AIDS without the associated opportunistic diseases have AIDS-related complex (ARC). Symptoms include fever, weight loss, diarrhoea, fatigue and night sweats found in conjunction with certain physical signs and abnormal laboratory results. Not everybody with AIDS has experienced ARC. However, almost all people with ARC ultimately develop AIDS although therapeutic intervention may slow this development.

2.17 More than a single disease, AIDS itself is a kaleidoscope of many disorders. Different problems may occur in a single, multiple or sequential fashion; these many be focal or may become disseminated, and they can affect virtually every body system.

2.18 In drug misusers, the principal manifestation of AIDS — ultimately affecting perhaps 70-80% of cases — is pneumocystis carinii pneumonia (PCP). Symptoms may develop slowly over 3 to 10 weeks with malaise, cough, fevers and progressive breathlessness on exertion. Early diagnosis and swift intervention are important but even so mortality may be 10 to 25%. Patients usually require hospital admission for a period or 2 to 4 weeks. Subsequently, prophylactic regimes are indicated to prevent recurrence which is common.

2.19 After PCP, the problem most likely to be seen in drug misusers with AIDS is candidal oesophagitis (thrush) causing swallowing difficulties. Oral thrush isn a bad sign in an infected individual and suggests early development of AIDS.

2.20 Central nervous system problems are also common and include various forms of meningitis, encephalitis and abscess formation. The AIDS dementia complex (ADC) may develop in 40% or so of AIDS patients often at a pre-terminal stage although it may occasionally occur earlier. It may be clinically difficult to distinguish ADC from drug induced encephalopathy.

2.21 There are certain features which, if developing, should prompt early referral to an HIV specialist. These include breathlessness, protracted fevers or weight •loss, increasing fatigue, bruising, oral thrush and the occurence of shingles. Similarly, an adverse prognosis is associated with progressive dropping T4 cell count, lack of reaction to a battery of skin antigen tests, the development of HIV antigen and of low blood counts.

HIV-Disease in injecting drug misusers

2.22 Injecting drug misusers are prone to a vast array of acute and chronic infections affecting many organs. In addition to those previously mentioned are viral hepatitis, sexually transmitted diseases and infection with human T cell lymphotrophic virus type I (HTLVI) which may cause leukaemia or lymphoma.

2.23 American and Italian studies have suggested that continuing users progress to AIDS at a faster rate than ex-users presumably due to factors such as debilitation and enhanced HIV activity. However, overall recent studies have not shown that injecting drug misusers progress at a faster rate than homosexuals, and possibly they may progress more slowly; the explanation for this could be age-related. Assessment of deterioration is complicated, however, by the similarity between HIV- and drug-related manifestations.

2.24 Evidence now suggests that the prognosis of serious, non-AIDS related infections is worse in individuals with HIV-infection. This is of particular significance for some injecting drug misusers who, as a result of their lifestyle, deprivation and unhygienic practices are exposed to a variety of potentially virulent micro-organisms. HIV-infection may act as an amplification of infections such as tuberculosis, septicaemia, endocarditis and bacterial pneumonia. For example, the mortality from endocarditis may be increased sixfold. New York has witnessed a significant increase in deaths among injecting drug misusers from such conditions. Because they are not classified as AIDS deaths, some researchers have argued that the real extent of HIV-related deaths among injecting drug misusers in the city may be under-estimated by as much as 100%. Deaths may include suicides as well as those as a result of infection.

2.25 Evidence from USA, Italy and Spain emphasises the individual and public health threat of tuberculosis in seropositive drug misusers. Its incidence has varied in 3 series of seropositives from 7 to 13 %. For the first time since the War, HIV-infection is causing a resurgence of tuberculosis in the indigenous population of New York with an increase of 36% in cases between 1984 to 1986. Tuberculosis may be pulmonary in site when it can be highly infectious (including to casual contacts), or extra-pulmonary when it is difficult to diagnose and, if disseminated, especially life-threatening. Extra-pulmonary tuberculosis has recently increased by 400% in injecting drug misusers in Brooklyn. However, a major difference between the UK and the USA in respect of tuberculosis, is that routine BCG immunisation is undertaken in the UK and this may confer a degree of individual and community protection.

2.26 Major concerns are often expressed about the compliance of seropositive drug misusers with care programmes. However, several recent studies have found that in centres where drug misusers have been treated with zidovudine compliance has been comparable to that among homosexual men, and both groups have enjoyed comparable medical benefits. Therefore a history of drug misuse should not per se influence decisions about treatment with drugs such as zidovudine which require considerable compliance and careful monitoring.

The Extent of HIV-Disease Among Drug Misusers

2.27 It is difficult to assess the potential extent of HIV-infection among past or current drug misusers. To the end of September 1988, of some 9,250 people in the UK who have been found to be seropositive, 1,520 have been injecting drug misusers. It is likely that these represent only a small proportion of the total infected. We have estimated that in 1986 there may have been between 37,000 and 75,000 regular injectors of notifiable drugs in the UK, supplemented by an unquantified number of injectors of other drugs, particularly amphetamines (Chapter 1, Part 1 Report). Additionally there will be a far greater number than this who experiment with injecting these drugs or who inject on an occasional or periodic basis. Many people may have injected drugs with shared equipment at some time in the past few years. Their level of risk will vary with the date HIV was first introducted into their locality; levels of seroprevalence since its introduction; and local patterns of sharing injecting equipment.

2.28 Our understanding of all of these factors is hampered by a lack of information. Available information on seroprevalence, for example, is inevitably based on relatively small samples of drug misusers who are regularly attending services. The highest rates have been recorded in Edinburgh (between 38% and 65% during 1985-86) and Dundee (39% in 1986). Reported rates elsewhere have generally been much lower (0.7% and 1.5% in London 1984-86, 4.5% in Glasgow during 1985) although St Mary's Drug Dependency Unit in London, which has a large proportion of Scottish and Irish clients, found a rate of 32 % in 1987. We recognise the many problems in obtaining information about seroprevalence within a system of voluntary testing. Nonetheless, while we know so little both about the extent and spread of HIV-infection, and the extent and nature of drug misuse, we are hindered not only in our ability to target and assess the effectiveness of preventive efforts, but also to plan services for those who many become ill. Efforts must be made to provide more reliable epidemiological data on drug misuse, and on HIV-infection among drug misusers.