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AIDS action -  Issue 3 - Testing

AIDS action  Issue 3         Page 1   2 

Tests: discrimination or discovery?

An AIDS awareness counsellor recently summed up her experience of society's response to AIDS: 'I believe that, although AIDS is a new disease, it is laying bare all the old prejudices and political injustices that already exist.' One area where this is most apparent is the misuse of testing for HIV infection.
 

 
Testing for HIV antibodies has become increasingly significant in AIDS control programmes. HIV screening can be a valuable tool for discovering more about the spread of the disease, making blood supplies safer and planning the allocation of health care resources and health education strategies. But, testing can also be used as a tool for discrimination - against individuals, groups of individuals, and whole nationalities.

This issue of AIDS Action looks at some of the practical and ethical implications of HIV testing; the importance of effective clinical diagnosis in developing countries and the nature of the AIDS virus. Guidelines for setting up workshops to increase AIDS awareness are also featured.

Why test?
HIV testing was initially developed for screening donated blood. Testing is now carried out for a variety of reasons and can be categorised in the following way: 'anonymous' screening, 'voluntary' testing and 'compulsory' testing. 

Anonymous screening appears to be the most effective and ethically acceptable way of ensuring the safety of blood supplies and measuring the rate of increase of HIV infection. But difficult ethical questions have arisen for the medical workers concerned. Should individuals 'anonymously' screened be informed if the results are positive? If so, what counselling and other support services can be offered? Although HIV infection is not always an indication that a person will go on to develop AIDS, knowing that they are infected creates anxiety for the individual concerned and their loved ones. Medical workers have nothing more to offer than treatment for opportunistic infections, if and when they occur - there is still no cure for AIDS.

Investing in people 
Widespread HIV screening requires many resources. Not only are testing kits expensive, but, until recently, most have required additional technical equipment for their use. Since no test is 100 per cent accurate, confirmatory tests should be carried out on all positive results. In many areas of the developing world, these are prohibitively expensive. Putting resources into HIV screening could have serious implications for vital, on-going primary health care programmes. Many argue that It is better to put available resources into AIDS education and counselling programmes, integrated with existing PHC activities, than into widespread HIV testing. 

Dr Fleischer, from the Medical Missions Institute in Wurzburg, currently evaluating new testing kits for use in developing countries, stresses: ' What we need is not investment in expensive testing equipment - already tests are being developed that don't need elaborate, technical equipment - what we need is investment in people. Workshops are needed about when to test, how to deal with the results responsibly and on setting up adequate counselling services. In the wrong hands, HIV testing can cause a lot of unnecessary suffering and harm.'

Compulsory testing
Compulsory testing is an aspect of AIDS control most likely to cause 'unnecessary suffering and harm'. The decision to test one group of people rather than another, is usually based on unproven assumptions about which sectors of the population are 'spreading' the disease. There is a danger that all those not singled out for screening will consider themselves to be not at risk, even where there is no evidence to suggest that levels of infection are higher in the screened group than in any other population sector. In the Philippines, for example, prostitutes have been brought in regularly by the police for screening, and their clients have not. In South Africa, black migrant workers from neighboring states are singled out for screening and those found positive are repatriated. Alan Whiteside, from the University of Natal, points out: 'The emphasis has been on black migrants being screened and repatriated and not on white foreigners. This is blatant racism, but South Africa is not alone in this.' In all countries, one of the greatest struggles in the fight against AIDS will be to ensure that criteria for HIV testing are guided by unbiased, humane principles - not by prejudiced assumption.

The international newsletter for information exchange on AIDS prevention and control.

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Explaining the nature of the virus that causes AIDS

The first cases of AIDS were recognised in the USA in 1981; the virus that causes it was identified in 1983 at the Institut Pasteur in Paris. It was initially named lymphadenopathy associated virus (LAV). Confirmation that this virus was the cause of AIDS came in 1984 from the National Cancer Institute in Bethesda, USA. It was renamed human T-lymphotropic virus type 3 (HTLV-3). In 1986 an international expert committee introduced the term human immunodeficiency virus (HIV). 

Recently a new AIDS virus has been identified in West Africa. This virus, which is related to the original AIDS virus and acts in a similar way, with similar routes of transmission, is spreading to other parts of the world. The first identified AIDS virus is now called HIV-1 and the variant, HIV-2.

Structure of HIV
 

Figure 1

 
HIV is a member of the retrovirus family of viruses. This family has been known for many years to cause a number of different diseases in animals. It is significant that other members of the family also cause immune deficiency (such) as feline leukaemia virus in cats. Some, also like HIV, cause central nervous system degeneration (such as visna virus in sheep) and anaemia (such as equine infectious anaemia virus). The structure of HIV-1 (HIV-2 is similar) is shown in figure 1. Like all retroviruses, HIV contains RNA in its core; the virus itself is surrounded by a fat-containing (lipid) envelope or 'coat'.

Figure 2 shows how the virus reproduces itself in human cells. Firstly, the virus needs to select cells to attach itself to - these are cells with a special 'receptor' known as the 'CD4 antigen'. This receptor occurs on cells in the body's immune system, the helper T lymphocytes, and on some macrophages. There is some evidence that other cells can support the growth of HIV, such, as those in the lining of the bowel (bowel epithelium) and in the brain (microglial cells).
 
Replication
When the virus has made contact with a CD4 antigen-carrying cell, it sheds its lipid coat and injects its RNA into the human cell. The single-stranded RNA then makes a copy of itself with the use of an enzyme, called reverse transcriptase. This results in double-stranded DNA which then inserts itself into the human cell DNA. Because HIV becomes part of the human cell's genetic material, infection of the cell is irreversible. Although it may be possible to develop a drug that suppresses the activity of the virus (keeping an infected person relatively healthy) there is no prospect of cure in the sense of eliminating the integrated viral DNA. 

The virus may remain dormant for months, or even years, but if the infected cells are activated by the body's immune system (fighting another disease) HIV will begin to reproduce itself, making copies that will go on to infect more human cells.

The viral DNA starts to instruct the human cell to produce viral components, such as viral proteins and RNA - the two main components of HIV The viral proteins migrate to the surface of the infected cell, where they stick out through its outer membrane. Then, by a process known as budding, multitudes of new viruses detach themselves from the infected host cell, and are taken away in the blood-stream to attach to other cells with CD4 receptors.

Infection with any other disease, i.e. activation of the immune system, is therefore likely to lead to the virus replicating; but there is some evidence that a few common viral infections such as herpes simplex virus and cytomegalovirus can specifically encourage the replication of HIV. Increased replication of the virus means that an infected person is more likely to develop full-blown AIDS. This is because replication of the virus leads to progressive destruction of infected cells, thus destroying the body's immune system and decreasing its ability to fight off infection with other diseases. With this in mind, the advice given to those who are infected with HIV - to lead a healthy lifestyle - a firm scientific basis. 

If the infection is primarily in the brain, viral replication will cause the brain to be diseased (encephalopathy), which will often result in dementia. Although the body's immune system does produce antibodies to the virus, they do not seem to be able to inactivate the virus. The virus in circulation is therefore able to spread to other parts of the body and can also be transmitted to sexual partners, passed an to others through infected blood, blood products, and other body fluids, and from an infected mother to her unborn child.

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Properties of the virus
HIV, like other viruses, is easily destroyed by boiling and steaming (autoclaving) (see WHO Report). The lipid-containing envelope of the virus can be destroyed by various chemicals in standard disintectants - hypochlorite, glutaraldehyde and formaldehyde, normally recommended for Hepatitis B virus - as well as by alcohols, acetone, phenol, and several detergents.

However, the lipid envelope can also protect the virus from dehydration. This means that contaminated fluid which has been allowed to dry, may still contain infectious virus, for hours or even days if kept at room temperature. It is important to ensure that any surfaces or clinical instruments contaminated with body fluids are treated with effective disinfectants.

Prospects for control of HIV
The principles for control of HIV are easily states but much less easily implemented. The absence of a vaccine, or a cure for AIDS, means that the only way of controlling the epidemic is to educate the public about the nature of the infection and how its spread can be avoided.

Dr Donald Jeffries, Reader in Clinical Virology, St Mary's Hospital Medical School, London W2 1 PG, UK.
 

Figure 2

 
HIV has two glycoproteins (a form of protein) in its lipid envelope, called gp 120 and gp 41. The 'gp' stands for glycoprotein; the numbers reflect the sizes. Inside the envelope is a structure called the core shell - this layer is made of a protein known as p 18. The core itself, which contains the RNA, is made of a protein called p 24. The glycoproteins and proteins of the virus are important since they act as antigens, that is, they stimulate the immune system to produce specific antibodies, which can be detected in a blood test (see pp. 4-5).

 

Explanation of scientific terms

RNA and DNA: Ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) store the genetic information of an organism i.e. the instructions for its growth and reproduction, in every living cell. Most cells or organisms carry their genetic Information in the form of DNA, which then makes a mirror-image copy of itself, RNA, which is used to make proteins - a vital component of living organisms.

Virus: Probably the simplest of all known organisms. Different viruses cause different diseases. A virus is not a complete cell, and only contains some genetic material and a coat of protein. It is not 'alive' in the scientific sense, because it needs other organisms to be able to reproduce, by invading other cells. Most viruses contain DNA as their genetic material.

Retrovirus: A virus which store its genetic material as RNA, not DNA. 'Retro' means backwards, so-called because the virus persuades the invaded cell to convert viral RNA back into DNA, which is 'backwards' to the cell's normal operation - which is to convert DNA into RNA (to make proteins or to reproduce itself). 

Immune system: This is the body's defence system against attack from viruses, bacteria and other organisms that cause disease or are harmful. The function of the immune system is to recognise and eliminate these.  A key element in this response is the production of antibodies; these recognise, and stick to, specific antigens (a protein or carbohydrate substance belonging to an organism that produces an immune response). The combined antibody/antigen can then be engulfed, or eaten up, by macrophages - other cells of the immune system. The helper T lymphocyte is a type or white blood cell, which has a very important role in the immune system. These cells carry the CD4 receptor, and are the main type of cell which HIV infects; thereby critically 'injuring' the body's ability to fight off infection.

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HIV testing in rural hospital

Blood testing for the human immunodeficiency virus (HIV) can play an important role in AIDS prevention and control. Many rural hospitals, which often lack basic laboratory equipment, are facing increasing demand for HIV testing, from epidemiologists, governments, doctors and individuals. Dr Fleischer offers some practical advice. 

There are three areas where testing is important: screening blood to be used for transfusions; screening populations or population sectors; and testing individuals. In all these areas careful consideration is required before setting up facilities for HIV testing.

Making blood transfusions safer
The World Health Organisation has estimated that around ten per cent of HIV infected individuals may have become infected following transfusions with blood contaminated with the virus. In areas badly affected by malaria, blood transfusion levels are high compared with western hospitals. Screening donated blood, or confidential screening of donors themselves, can help to greatly reduce the risk of using infected blood.

The risk is not entirely eliminated by testing: the test is not for the virus itself, but for antibodies to the virus produced in the blood of an infected person. This means that with any antibody test, there is a 'window' period of a number of weeks, or even months; between initial infection and the time when the body starts to produce antibodies; during which time a test for HIV antibodies will be negative, even if the virus is present. In most countries, screening donated blood is carried out on an 'anonymous' basis: names are not registered and donors are not informed of the results. 

Screening the population
There is a clear need to obtain epidemiological data concerning the prevalence and patterns of infection in any given population, in order to more accurately plan health education strategies and the allocation of resources for prevention and care.

Epidemiological surveys should be carried out in ways that respect the confidentiality of those being tested. Some countries are carrying out 'anonymous' screening of blood samples taken for other purposes (e.g. pregnant women attending maternity clinics) to gain information on the spread of the disease. Patients are not informed of the testing or the results, and no names are recorded. 

In contrast, other countries are carrying out 'compulsory' screening, which means that testing is not voluntary, and that positive results usually have a direct affect on the rights of the individual ego in relation to where they can live or work.

Voluntary testing of individuals
When a medical worker suspects from looking at the clinical symptoms that a patient is suffering from AIDS, serological evidence of HIV may be useful. Some individuals - with or without any signs of illness - may have special reasons for wanting a test, such as sexual partners of confirmed AIDS patients. This is known as voluntary testing, and results are given to the individual concerned. It is important that adequate pre-test counselling is given to all those agreeing to, or asking for; blood tests so that the full implications are understood.

Confidentiality
When introducing HIV testing into a hospital or clinic, all staff involved should understand that carrying out such tests is not a solution to the threat of AIDS; indeed, testing con further complicate matters both socially and morally. Procedures and criteria for testing should be agreed upon and understood by all staff. Hospital staff must also discuss who will have access to the results and what action s to be taken.

Tests are carried out in the laboratory, and this puts the laboratory technician - usually the most senior - in a trusted position; s/he should be trusted by the other staff.

A system of double record keeping can help to keep results confidential: one laboratory book stores the names and dates of patients tested, and gives a test reference number for each patient. The second book just registers a number for each patient (without the name) and the test result. It should be agreed who has access to the second book. 

It should also be agreed whether or not individuals are to be told their result. Individuals who have requested tests will of course want to know the result; results should only be given to those who want to know. The ethics of HIV testing are complex - some hospitals have decided against testing altogether under the present circumstances.

Practical considerations 
Hospitals setting up testing facilities should make sure that they have the personnel to ensure effective and accurate use of tests. It is very dangerous to buy testing kits, or to receive donated ones, without ensuring that laboratory staff and others receive the necessary introductory courses. Training should cover technical problems, accurate reading of results, and the wider social implications. Such a course could be arranged at a regional centre for a small group of technicians, with follow-up from a central laboratory.

The necessary organisational and technical resources should also be available. Introduction of HIV testing for blood transfusion purposes requires the storage of blood for a minimum of four hours (for currently available ELISA tests). A small, refrigerated blood storage unit is necessary for this. Once a hospital claims to be screening blood before transfusion, tests must be carried out daily, or more often in emergencies. This requires investment in laboratory staff time, and in establishing effective supply and storage systems.

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Clinical case definition in developing

In most developing countries, routine blood testing for HIV infection is too expensive - especially where further confirmatory tests are necessary. Clinical diagnosis of AIDS can be particularly useful in these circumstances. Since endemic tropical and sexually transmitted diseases can complicate the picture, clinical case definitions for AIDS should be evaluated in the light of local disease patterns.

As in the United States and Europe, HIV infection in the developing world can directly affect the body's tissues, or can indirectly lead to opportunistic infections and tumours. However, there are clinical differences between the developed and developing world. For example, in the United States a major AIDS-related lung disease is pneumocystis carinii pneumonia (PCP) - a previously rare form of pneumonia; in Africa, PCP is almost unknown, but higher levels of the lung infection tuberculosis appear to be AIDS-related; one survey has revealed that, of 159 patients in a TB sanatorium in Zaire, 33% were HIV antibody positive(1).

Given differences in disease patterns between the developed and developing world, applying clinical and laboratory data from developed countries - where some of the earliest detailed observations were made - may result in incorrect diagnosis in the developing world. 

A clinical case definition of AIDS in Africa was introduced by the WHO in 1985 (2). It has since been revised to place greater emphasis on HIV infection status (3). The 1985 clinical definition of adult AIDS in Africa was evaluated in Zaire in a study involving 174 patients(4) and found to have a specificity of 90% i.e. a low number of false positives (for definitions of terms see p5).

The study also found that, of the 'major' symptoms and signs of AIDS (weight loss of more than 10%, fever or chronic diarrhoea lasting more than a month) diarrhoea was the most specific. All 'minor' symptoms and signs (including: cough lasting longer than one month; painful genital ulceration lasting longer than one month; itching and inflamed skin; recurrent herpes zoster infection/shingles) were very specific, but less sensitive (resulting in a higher number of false negatives). It is important to remember that each symptom/sign alone is not necessarily sufficient for the diagnosis of AIDS - a syndrome which involves a number of infections. For a list of diseases which are by themselves sufficient for the diagnosis of AIDS see 1987 CDC/WHO revised case definition.

Case definitions are only guidelines. The tropical physician should obtain an overall picture of a patient's health in the context of endemic disease patterns, as well as concentrating on the individual symptoms of the patient. Doctors and other health staff will learn from each case history and should be self" critical in their application of a clinical case definition of AIDS.

With knowledge of endemic tropical diseases, careful recording of case histories and good clinical judgment, the tropical physician should be able to distinguish between HIV-related opportunistic infections and endemic tropical ones, like visceral leishmaniasis* (which can mimic AIDS-related intestinal diseases i.e. enteropathic AIDS) and tuberculosis. It will also become apparent that the endemic form of Kaposi's sarcoma (KS) in parts of Africa, differs from the 'aggressive' form of AIDS-related KS, which is found in developed countries.

The spread of AIDS in Africa (9,788 AIDS cases were registered by the WHO, in March 1988, with HIV infection in individuals estimated at two million) will continue to influence tropical disease patterns. Both for surveillance and diagnostic purposes, I strongly recommend that clinical evaluation is carried out in the first instance, followed by reliable serological examination for HIV infection where possible.

Dr C E Anyiwo, Expert Advisory Committee on AIDS and senior lecturer and consultant in medical microbiology, College of Medicine, Lagos University Teaching Hospital, Nigeria.

1 Mann JM et al. Association between HTLV-III/LAV infection and tuberculosis in Zaire. JAMA 1986; 256: 3099-3102. 
2 WHO Report (AIDS Action issue 1, insert) November 1981
3 Weekly Epidemiological Record, No. 112, 118 January; 1988. 
4 Colebunders et al. Evaluation of a clinical case definition of acquired immunodeficiency syndrome in Africa. The Lancet, February 28, 1987

* Transmitted by the bite of sandflies. Symptoms include fever, progressive anaemia, leucopenia. Also known as Kalaazar and dumdum fever.
 

 
Taken from AIDS in Africa: a review of medical, public health, social science and popular literature (see page 8).

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AIDS action  Issue 3    7   Page 8   9 

The following resource list is part of a regular series; here we list a selection of a broad range of materials, covering technical, health education and social aspects of AIDS, from developed and developing countries. Readers are encouraged to send information about additional materials produced in their own countries.

Equipment

Equipment for Charity Hospitals Over-seas (ECHO)
Ullswater Crescent, Coulsdon Surrey, UK.

Activities: Provides low-cost HIV blood testing kits, needles, syringes, gloves, vehicles for AIDS outreach programmes. A major blood testing kit now supplied by ECHO is the Karpas test, which detects (and types) the presence of both HIV1 and HIV2 antibodies. Karpas screening kits are probably the cheapest now available. The test can be completed within one hour and only requires 100-fold bench microscope to verify positive reaction and a domestic refrigerator for storage of the reagents Also supplied: Wellcozyme, Dupont and Abbot tests.

Books/Pamphlets

AIDS in Africa: A review of Medical, Public Health, Social Science and Popular Literature
By Drs B J Johnson and R S Pond, February 1988. Report containing useful reference material, dealing with medical, epidemiological, social, cultural and political aspects. Includes tables and figures and bibliography for background reading. 
Available from: Misereat; (Episcopal Organisation for Development Cooperation) Postfach 1450, Mozartstrasse 9, D-5100 Aachen, West Germany.

Preventing a Crisis
Manual designed for family planning association and other health personnel. Five chapters explore how each component of a family planning programme might be strengthened or adapted to prevent HIV transmission; including service delivery, counselling, training, health education, women and development, male motivation and working with young people. Available in English, in book or loose-leaf format. Arabic, French, Portuguese and Spanish versions due out shortly.  
Available from: IPPF Distribution Unit, PO Box 759, Inner Circle, Regent's Park, London NW1 4LQ, UK. Price: U5$5.00/£2.00.

Blaming Others: Prejudice, Race and Worldwide AIDS 
By Renee Sabatier, with contributions from 12 journalists from developing countries. Examines some of the emotive issues connected with AIDS, arguing that blame and prejudice are undermining AIDS campaigns. Questions asked include: Has Western reporting on AIDS in the third world been hysterical? Is research racially biased? How widespread is promiscuity?
Available From: The Panos Institute, 8 Alfred Place, London WC1E 7EB, UK. Price: £4.95.

Report of the Meeting on Criteria for HIV Screening programmes 
Summarises criteria that should be considered in planning and implementing HIV screening programmes. Produced by WHO/GPA, Geneva May 1987 document GLO/87.2. 
Available from: WHO/GPA, Publications.

Teaching Materials

One of a series of posters produced for use in schools by the Ministry of Education AIDS Control Programme, Uganda, with assistance from UNICEF Schools pack contains posters, flip charts, and teachers' guide to AIDS control and human reproduction. Contains excellent ideas for teaching methods, and classroom activities. For further information contact: Mary Owor/Martha George, UNICEF, PO Box 7047; Kampala, Uganda.

AIDS Information for Secondary Schools
Booklet intended for secondary school students, their teachers and parents, and other young people worried about AIDS. Explains what AIDS is, what causes it, how it is spread and how it can be prevented. Also deals with false rumours, and uses clear illustrations. Includes 'true or false? ' questionnaire (answers on back page) and personal questionnaire on sexual and other risk behaviour. 
Produced by, and available from, the Health Education Unit, Ministry of Health, Zambia, with support from the Norwegian Ministry of Development Cooperation (NORAD), Lusaka, Zambia. Distributed in Zambia free of charge.

AIDS FACTS PLUS
A multi-purpose resource pack, as an ex-tension to the original teaching pack AIDSFACTS. Contains 25 A4 sheets (can be easily photocopied) designed to be used in a variety of teaching situations and as background material. Also discusses social, medical, moral and sexual issues such as AIDS and the Workplace', 'Being HIV positive' and 'Care of the AIDS Patient'. 
Available from the publishers, Cambridge Science Books, Tracey Hall, Cockburn Street, Cambridge CB1 3NB, UK. Price: £76.95 incl. p&p. Also from Cambridge Science Books: AIDS: Questions and Answers by Dr V Daniels - an excellent general introduction price: £6.95, and A Guide to Clinical Counselling, by R Miller and R Bor - a practical handbook on the psycho-social management of AIDS patients, their families and loved ones. Intended for doctors, nurses, counsellors and other health care professionals.

Sources of Information

Aids Information 
A current awareness bulletin from the Oncology Information Service, Medical and Dental Library, The University, Leeds LS2 9JT, UK. Scans 1,300 major international biomedical journals, and extracts every paper on AIDS and HIV, giving abstracts and authors' addresses. Published monthly. Price: £9.00 (UK National Health Service affiliates). Outside UK, enquiries to: Swets Publishing Service, PO Box 825, 2160 SZ LISSE, The Netherlands.

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Guidelines on sterilisation and high-level disinfection methods effective against human immunodeficiency virus (HIV)

Due to the great importance of this activity to health care workers in the field, we are reproducing these guidelines in their entirety.

The human immunodeficiency virus (HIV) can be transmitted from one person to another through the use of non-sterile needles, syringes, and other skin-piercing and invasive instruments. Proper sterilisation of all such instruments is therefore important to prevent its transmission. HIV is very sensitive to standard methods of sterilisation and high-level disinfection, and methods designed to inactivate other viruses (e.g., hepatitis B virus) will also inactivate HIV.

Heat is the most effective method for inactivating HIV; methods for sterilisation (1) and high-level disinfection (2) based on heat are therefore the methods of choice. High-level disinfection by boiling is feasible in most circumstances, as this requires only a source of heat, a container, and water. In practical and field settings, high-level disinfection with chemicals is far less reliable.

HIV transmission
HIV has been found in various body fluids from persons infected with the virus. However, only blood, semen and vaginal and cervical secretions have been implicated in HIV transmission. Nevertheless, as all body fluids (including pus and other infected discharges and infected body cavity fluids, such as pleural fluid and cerebrospinal fluid) may contain blood or white blood cells, it is essential that all medical instruments for invasive procedures (including needles and syringes) should be cleaned, then sterilised or given high-level disinfection, for each separate patient, to prevent transmission of HIV.

Methods of sterilisation and disinfection

It is imperative that all instruments be cleaned thoroughly before being sterilised or disinfected at high level by any method. It is suggested, particularly in health care settings where the prevalence of HIV infection among patients is high, that medical instruments should be soaked for 30 minutes in a chemical disinfectant before cleaning. This will give further protection to the personnel from exposure to HIV during the process of cleaning.

Sterilisation by steam
Steam sterilisation (autoclaving) is the method of choice for reusable medical instruments including needles and syringes. An inexpensive type of autoclave is an appropriately modified pressure cooker (WHO/UNICEF type). (3) Autoclave and pressure cookers should be operated at 121°C (250°F) equivalent to a pressure of 1 atmosphere (101 kPa, 151 b/in²) above atmospheric pressure, for a minimum of 20 minutes. 

WHO and UNICEF have collaborated in developing a portable steam steriliser containing an insert (rack), where needles, syringes and other instruments commonly used in health care settings can be fitted.

Sterilisation by dry heat 
Sterilisation by dry heat in an electric oven is an appropriate method for instruments that can withstand a temperature of 170°C (340°F). This method is therefore not suitable for reusable plastic syringes. An ordinary electric household oven is satisfactory for dry heat sterilisation. The sterilisation time is two hours at 170°C (340°F).

High-level disinfection by boiling
A high level of disinfection is achieved when instruments, needles, and syringes are boiled for 20 minutes. This is the simplest and most reliable method for inactivating most pathogenic microbes, including HI\/; when sterilisation equipment is not available. Hepatitis B virus is inactivated after a few minutes of boiling and it is probable that HI\/; which is very sensitive to heat, is also inactivated after several minutes of boiling. However, in order to be sure, boiling should be continued for 20 minutes.

High-level disinfection by soaking in chemicals
Many disinfectants recommended for use in health care facilities have been found to inactivate HIV in laboratory testing. However, in practice, chemical disinfectants are not reliable, because they may be inactivated by blood or other organic matter present. Furthermore, they must be prepared carefully. They may also rapidly lose their strength, especially when stored in a warm place. Chemical disinfection must not be used for needles and syringes. Chemical disinfection for other skin-cutting and invasive instruments should only be employed as the last resort, if neither sterilisation nor high-level disinfection by heat is possible and then only if the appropriate concentration and activity of the chemical can be ensured and if the instruments have been thoroughly cleaned prior to soaking in the chemical disinfectant.

The following chemical disinfectants have been shown to be effective in inactivating HIV: 

sodium hypochlorite, 0.1-0.5% available chlorine; 
chloramine 2% (tosylchloramide sodium); 
ethanol 70%;
2-propanol (isopropyl alcohol) 70%;
polyvidone iodine 2.5%;
formaldehyde 4%;
glutaral (glutaraldehyde) 2%;
hydrogen peroxide 6%; 

Other commonly used disinfectants may also be effective, but laboratory data on their effectiveness are not available.

AIDS: a worldwide effort will stop it 

AIDS action  Issue 3    10  Page 11  12 

AIDS action  Issue 3    11  Page 12      

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