ABC of HIV and AIDS

Michael W. Adler, Simon G. Edwards, Robert F. Miller, Gulshan Sethi, Ian Williams, Michael W. Adler, Simon G. Edwards, Robert F. Miller, Gulshan Sethi, Ian Williams

• Éditeur: BMJ Books
• Année: 2012
• ISBN:
  9781118425909
• Édition: 6
• Sujet: Medizin
• Sous-sujet: AIDS & HIV

An authoritative guide to the epidemiology, incidence, testing and diagnosis and management of HIV and AIDS.

From an international expert editor and contributor team, this new sixth edition includes expanded coverage of HIV testing, assessment and routine follow up and new chapters outlining problematic conditions associated with HIV and AIDS. Prevention strategies, early diagnosis and antiretroviral drugs and pharmacotherapy are covered in detail as well as children and women with HIV. It also addresses key psychological and mental health issues, patient perspectives and the role of patient engagement.

As knowledge into the illness grows and major advances in HIV therapy see more people living with HIV in the community, the ABC of HIV and AIDS, 6e provides clear practical guidance for general practitioners, hospital doctors, nurses, medical students, counsellors, allied health workers and anyone working and caring for patients with HIV and AIDS.

Chapter 1

Development of the Epidemic

B. Sultan¹ and M. W. Adler²

¹University College London, Mortimer Market Centre, London, UK

²University College London Medical School, London, UK

Overview

The commonest mode of transmission of the virus is through sexual intercourse

The growth of the epidemic has appeared to stabilize

HIV continues to exhort a huge public health and economic burden

In 2009, there were 33.3 million people living with HIV worldwide

Sub-Saharan Africa has experienced a disproportionate burden of the global HIV epidemic

10 million people who are eligible for treatment under World Health Organization guidelines are still in need of treatment

Development of the epidemic (Boxes 1.1 and 1.2)

The first recognized cases of the acquired immune deficiency syndrome (AIDS) occurred in the summer of 1981 in the USA. Reports began to appear of Pneumocystis carinii (now known as jirovecii) pneumonia and Kaposi sarcoma in young men, who it was subsequently realized were both homosexual and immunocompromised. Even though the condition became known early on as AIDS, its cause and modes of transmission were not immediately obvious. The virus, human immunodeficiency virus (HIV), now known to cause AIDS in a proportion of those infected, was discovered in 1983. Subsequently a new variant has been isolated in patients with West African connections, HIV-2.

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Box 1.1 Early history of the HIV epidemic

• 1981 Cases of Pneumocystis carinii pneumonia and Kaposi sarcoma in the USA
• 1983 Virus discovered
• 1984 Development of the antibody test
• 1987 Introduction of zidovudine therapy
• 1995 Formation of United Nations Programme on AIDS (UNAIDS)
• 1996 Introduction of highly active antiretroviral therapy (HAART)
• 2003 The ‘3 by 5’ campaign is launched to widen access to treatment

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Box 1.2 HIV epidemic—the bottom line

UN Millennium Development Goal Six

• Target 6A. Have halted by 2015 and begun to reverse the spread of HIV/AIDS
• Target 6B. Achieve, by 2010, universal access to treatment for HIV/AIDS for all those who need it.

‘Growth in investment for the AIDS response has flattened for the first time in 2009. Stigma, discrimination, and bad laws continue to place roadblocks for people living with HIV and people on the margins…. This new fourth decade of the epidemic should be one of moving towards efficient, focused and scaled-up programmes to accelerate progress for Results. Results. Results’

Michel Sidibé, Executive Director UNAIDS, UNAIDS Report on the Global AIDS Epidemic 2010

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Thirty years on and with the introduction of combination antiretroviral therapy (cART), where it is widely available, the clinical picture of HIV has changed from a fatal illness to that of a chronic condition. There has been an increase in the number of people living with diagnosed HIV as a result of fewer deaths from AIDS and ongoing high rates of HIV diagnosis. In developed countries, where cART has been available from its inception, an ageing cohort is now seen, and people with HIV are living near-normal life expectancies. Consequent to this has arisen the challenges of managing the co-morbidities associated with age and the long-term consequences of cART. Despite this, more than 10 million people worldwide who require cART are not able to access it, and HIV continues to exhort a huge public health and economic burden. The last decade has seen consistent global efforts to address health, development and the HIV epidemic, starting with the United Nations (UN) Millennium Development Goals (MDGs). Despite extensive progress, many countries have failed to achieve MDG Six, which is in part to halt and reverse the spread of HIV (Box 1.2)

Transmission of the virus (Box 1.3)

HIV has been isolated from semen, cervical secretions, lymphocytes, cell-free plasma, cerebrospinal fluid, tears, saliva, urine and breast milk. This does not mean, however, that these fluids all transmit infection, as the concentration of virus in them varies considerably.

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Box 1.3 Transmission of the virus

Sexual intercourse

• anal
• vaginal
• oral

Contaminated needles

• intravenous drug users
• needlestick injuries

Mother to child

• in utero
• at birth
• breastfeeding

Tissue donation

• blood transfusion
• organ transplantation

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Particularly infectious are semen, blood and possibly cervical secretions. Infection can occur after mucosal exposure to infected blood or body fluids.

The commonest mode of transmission of the virus throughout the world is through sexual intercourse. Unprotected anal and vaginal intercourse carry the highest risk of transmission, and the promotion of condom use has been the focus of prevention efforts.

Transmission also occurs through the sharing or reuse of contaminated needles by injecting drug users, which continues to drive the epidemic in Eastern Europe.

Transmission from mother to child occurs in utero, during labour and through breastfeeding. Transmission rates can be between 15% and 45% without intervention, and less than 5% with effective interventions. Mother-to-child transmission (MTCT) of HIV still significantly contributes to child mortality worldwide. However, the increase in access to services for preventing MTCT has led to fewer children being born with HIV. Use of cART during pregnancy, and at the time of birth, has been the mainstay of intervention strategies (see Chapters 17 and 18). In the UK, universal antenatal screening and access to cART have virtually eliminated MTCT. Globally, an estimated 370 000 children were newly infected with HIV in 2007, a fall of 24% from 5 years previously. UNAIDS called for the elimination of new paediatric HIV infections by 2015. It recommends that countries adopt a policy that HIV-positive mothers or their infants take ART while breastfeeding to prevent HIV transmission.

Contaminated blood products have previously contributed to the transmission of HIV, but universal screening has almost eliminated this mode of transmission in developed countries. Healthcare workers can rarely be infected through needlestick injuries and skin and mucosal exposure to infected blood or body fluids.

Growth and size of the epidemic (Table 1.1, Figure 1.1)

The growth of the epidemic has appeared to stabilize. Globally, there are fewer AIDS-related deaths and a steady decline in the number of new HIV infections since the late 1990s. In 2009, there were 33.3 million people living with HIV. There were 2.6 million new infections, which is 21% fewer than in 1997 (3.2 million) when the number of new infections reached its peak. HIV remains undiagnosed in 40% of people. The HIV incidence in 33 countries has fallen by 25% between 2001 and 2009, with 22 of these countries being in sub-Saharan Africa. However, in seven countries there has been an increase of more than 25% in the same time period. These include five countries in Eastern Europe and Central Asia.

Table 1.1 Regional HIV and AIDS statistics 2009.

Figure 1.1 Estimated adult and child deaths from AIDS, 2009.

Even though North America and Europe experienced the first impact of the epidemic, infections with HIV are now seen throughout the world, and the major focus of the epidemic is in resource-poor countries.

UK, Western Europe and USA

The number of people living with HIV in North America and Western and Central Europe has increased, with a 30% rise since 2001, and reached an estimated 2.3 million people in 2009. Heterosexual transmission represents about 50% of new HIV infections. In 2007, almost 17% of these new infections were among people from countries with generalized epidemics. The data are indicative of a resurgence of the HIV epidemic among men who have...