Blood and blood products
HIV has been transmitted following transfusion of whole human blood and blood components and the administration of clotting factor concentrates such as Factor VIII, manufactured from pooled plasma and used in the treatment of haemophilia. The routine screening of donor blood for the presence of HIV antibodies (indicating ongoing infection) and the self-exclusion of donors who, on the known means of transmission, may have been exposed to HIV will substantially decrease (but not totally eliminate) infection from blood transfusions. Between the introduction of screening in 1985 and the end of June 2000, only two instances of HIV transmission from transfused blood were reported in the UK. In addition to careful donor selection and HIV screening, viral inactivation processes (e.g. heat treatment, introduced in the UK in 1985) have virtually eliminated the risk of HIV transmission from the use of clotting factor concentrates used for the treatment of haemophilia in the UK.30
Donor organs and tissues for transplantation
Donor organs (kidneys, corneas, hearts, etc.) and tissues (e.g. semen used for artificial insemination) are a potential risk and individuals whose previous behaviour or life events have put them at risk of acquiring HIV infection are advised not to donate organs or to carry donor cards. The routine screening of donors for HIV infection will diminish this risk substantially. However, the risk will not disappear completely, as the donor may have only recently become infected and serological tests for HIV infection may be negative. This risk of donated semen can be reduced by the voluntary self-exclusion of donors who may have been exposed to HIV, initially screening donors, and the exclusive use of cryopreserved donor semen, stored for 3–6 months and not used until the donor has been re-tested for HIV infection. The use of fresh semen in artificial insemination programmes will remain a potential risk and is not recommended.
Iatrogenic transmission 39
Blood transfusion/
blood component therapy
Organ/tissue transplantation
Artificial insemination
HIV-contaminated equipment used
during invasive procedures
HIV-infected healthcare
workers Iatrogenic
transmission
FIGURE 4.4 Iatrogenic transmission.
HIV-contaminated equipment used for invasive procedures
Unsterilized equipment contaminated with HIV and used in nursing, medical, surgical or dental invasive procedures is clearly a risk to clients and, in many parts of the world where resources are limited, this may be a significant mode of transmission for HIV.31 Other unsterilized equipment used for acupuncture, tattooing and body piercing may also present a risk to clients.
HIV-infected healthcare workers
Although there have been many cases of healthcare workers becoming occupationally exposed to, and sometimes infected with, HIV, there have only been a few definite cases of HIV-infected healthcare workers transmitting HIV to patients, or of patient-to-patient transmission of HIV in a healthcare facility.32,33Healthcare professionals need to have a real insight into this issue, which is discussed in more detail in Chapters 14 and 15.
Summary
Throughout the world, millions of people are becoming infected with HIV every year as a result of being sexually exposed to this virus. Its success in establishing a near-perpetual global pandemic is owed in no small part to its ability to transmit itself from person to person during one of the most frequent, intimate and private of human behaviours. Added to this are the risk to children from mother-to-infant transmission, the risk to women from unsafe blood transfusions, the risk to those on the margins of society, such as commercial sex workers, men who have sex with men and drug users – all spinning around creating a seemingly unstoppable whirlwind of vulnerability driving national epidemics out of control. It is by having a clear understanding of how this virus is transmitted that nurses and other healthcare professionals can effectively engage in patient education encounters designed to prevent further exposure and infection, based not on myths, but on scientific fact.
REFERENCES
1. Anonymous. The Durban Declaration. International AIDS Society Newsletter December 2000; 17(1):14.
Prologue to Chapter 5
We have so far plotted the growth of this global pandemic in Chapter 1, noting the general trend of escalation in most nations. In Chapters 2 and 3, we then explored the causes of AIDS, reviewing both the general biology of viruses and the specifics of retroviruses, the family of viruses to which HIV belongs. In this chapter we clarified the known means of HIV transmission, especially noting that most people become infected as a result of being sexually exposed to this virus. Before we examine the pathological consequences of being infected, especially the deleterious effects HIV infection has on the immune system (immunopathogenesis), we need to understand how this system protects us against infectious diseases. That is what is reviewed in the next chapter, in order to prepare for an exploration of immunopathogenesis in Chapter 6.
2. Gallo RC, Salahuddin SZ, Popovic M et al. Frequent detection and isolation of cytopathic retroviruses (HTLV-III) from patients with AIDS and at risk for AIDS.
Science 1984; 224:500–3.
3. Zagury D, Bernard J, Leibowitch J et al. HTLV-III in cells cultured from semen of two patients with AIDS. Science 1984; 226:449.
4. Pudney J, Oneta M, Mayer K et al. Pre-ejaculatory fluid as potential vector for sexual transmission of HIV-1 [Letter]. Lancet 1992; 340:1470.
5. Groopman JE, Salahuddin SZ, Sarngadharan MG et al. HTLV-III in saliva of people with AIDS-related complex and healthy homosexual men at risk for AIDS. Science 1984; 226:447–9.
6. Fujikawa LS, Palestine AG, Nussenblatt RB et al. Isolation of human T-lymphotropic virus type III from the tears of a patient with the acquired immune deficiency syndrome. Lancet 1985; ii:529–30.
7. Thirty L, Sprecher-Goldberger S, Jonckheer T et al. Isolation of AIDS virus from cell-free breast milk of three healthy virus carriers. Lancet 1985; ii:891–2.
8. Levy JA, Hollander H, Shimabukura J et al. Isolation of AIDS-associated retroviruses from cerebrospinal fluid and brain of patients with neurological symptoms. Lancet 1985; ii:586–8.
9. Anonymous. Global AIDS surveillance Part II. Weekly Epidemiological Record (WER) December 2000; 48:386–92.
10. Joint United Nations Programme on AIDS (UNAIDS), World Health Organization (WHO). Report on the Global HIV/AIDS Epidemic. Geneva: UNAIDS and WHO, June 2000, UNAIDS/00, 13E, 135 pp. Available from UNAIDS or online at:
http://www.unaids.org/
11. Vittinghoff E, Douglas J, Judson F, McKirnan D, MacQueen K, Buchbinder SP. Per-contact risk of human immunodeficiency virus transmission between male sexual partners. American Journal of Epidemiology 1999; 150:306–11.
12. Vernumd SH, Tabereaux PB, Kaslow RA. Epidemiology of HIV sexual transmission. In:
Merigan TC, Bartlett JG, Bolognesi D (eds), Textbook of AIDS Medicine, 2nd edn.
Baltimore: Williams & Wilkins, 1999, 101–9.
13. Rothenberg RB, Scarlett M, del Rio C, Reznik D, O’Daniels C. Oral transmission of HIV. AIDS 1998; 12:2095–105.
14. PHLS AIDS and STD Centre – Communicable Disease Surveillance Centre, and Scottish Centre for Infection & Environmental Health. AIDS/HIV Quarterly Surveillance Tables – Cumulative UK Data to end September 2002. October 2002, 56:02/3. Available online at: http://www.phls.co.uk/
15. Mastro TD, de Vincenzi I. Probabilities of sexual HIV-1 transmission. AIDS 1999;
13(Suppl. A):S75–82.
16. Vernazza PL, Eron JJ, Fiscus SA, Cohen MS. Sexual transmission of HIV: infectiousness and prevention. AIDS 1999; 13:155–66.
17. Quinn TC, Wawer MJ, Sewankambo N et al. for the Rakai Project Study Group. Viral load and heterosexual transmission of human immunodeficiency virus type 1. New England Journal of Medicine 2000; 343:921–9.
18. Nelson KE, Rungruengthanakit K, Margolick J et al. High rates of transmission of subtype E human immunodeficiency virus type 1 among heterosexual couples in Northern Thailand: role of sexually transmitted diseases and immune compromise.
Journal of Infectious Diseases 1999; 180:337–43.
19. Ghys A. HIV shedding, STD and immunosuppression. AIDS 1997; 11:F-85–93.
References 41
20. Wawer MJ, Sewankambo NK, Serwadda D et al. and the Rakai Project Study Group and Ronald H. Gray. Control of sexually transmitted diseases for AIDS prevention in Uganda: a randomised community trial. Lancet 1999; 353:525–35.
21. Clapham PR, Weiss RA. The virus and its target cells. In: Merigan TC, Bartlett JG, Bolognesi D (eds), Textbook of AIDS Medicine, 2nd edn. Baltimore: Williams & Wilkins, 1999, 13–21.
22. Weiss H, Quigley MA, Hayes RJ. Male circumcision and risk of HIV infection in sub-Saharan Africa: a systematic review and meta-analysis. AIDS 2000; 14:2361–70.
23. Halperin DT, Bailey RC. Male circumcision and HIV infection: 10 years and counting.
Lancet 1999; 354:1813–15.
24. Szabo R, Short RV. How does male circumcision protect against HIV infection? British Medical Journal 2000; 320:1592–4.
25. Holmberg SD. Risk factors for sexual transmission of human immunodeficiency virus.
In: Curran J, Essex M, Fauci AS (eds), AIDS: Etiology, Diagnosis, Treatment and Prevention, 4th edn. Philadelphia: Lippincott-Raven, 1997, 569–75.
26. Chaisson MA, Stoneburner RL, Hildebrandt DS et al. Heterosexual transmission of HIV-1 associated with the use of smokable freebase cocaine (crack). AIDS 1991;
5:1121–6.
27. Centers for Disease Control. Unexplained immunodeficiency and opportunistic infections in infants – New York, New Jersey, California. Morbidity & Mortality Weekly Report (MMWR) 17 December 1982; 31:665–7.
28. Oleske J, Minnefor A, Cooper R et al. Immune deficiency in children. Journal of the American Medical Association 1983; 249:2345–9.
29. UNAIDS/WHO. AIDS Epidemic Update (UNAIDS/02.58E). Geneva: Joint United Nations Programme on HIV/AIDS and the World Health Organization, December 2002. Available online from: http://www.unaids.org
30. PHLS AIDS and STD Centre – Communicable Disease Surveillance Centre, and Scottish Centre for Infection & Environmental Health. AIDS and HIV infection in the United Kingdom: monthly report. Communicable Disease Report 29 September 2000;
10:357–8.
31. Velandia M, Fridkin SK, Cardenas V et al. Transmission of HIV in a dialysis centre.
Lancet 1995; 345:1417–22.
32. Centers for Disease Control. Update: Transmission of HIV infection during an invasive dental procedure – Florida. Morbidity & Mortality Weekly Report (MMWR) 14 June 1991; 40:377–81.
33. Lot F, Séguer JC, Fégueux S et al. Probably transmission of HIV from an orthopaedic surgeon to a patient in France. Annals of Internal Medicine 1999; 130:1–6.
Understanding immunology
Learning outcomes
After studying and reflecting on the material in this chapter, you will be able to:
■ describe the components of innate (natural) immunity and discuss their role in protecting people from diseases;
■ compare and contrast cell-mediated and humoral adaptive (acquired) immune responses and describe how these two systems co-operate to mount a specific immune response following exposure to specific antigens;
■ describe the role of cytokines in facilitating an effective immune response.