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Unit 3: Biology, Transmission, Natural History, Prevention and Treatment of HIV Infection and AIDS

Unit 3: Biology, Transmission, Natural History, Prevention and Treatment of HIV Infection and AIDS. #1-3-1. Warm Up Questions: Instructions. Take five minutes now to try the Unit 3 warm up questions in your manual. Please do not compare answers with other participants.

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Unit 3: Biology, Transmission, Natural History, Prevention and Treatment of HIV Infection and AIDS

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  1. Unit 3: Biology, Transmission, Natural History, Prevention and Treatment of HIV Infection and AIDS #1-3-1

  2. Warm Up Questions: Instructions • Take five minutes now to try the Unit 3 warm up questions in your manual. • Please do not compare answers with other participants. • Your answers will not be collected or graded. • We will review your answers at the end of the unit. #1-3-2

  3. What You Will Learn • By the end of this unit you should be able to: • explain the basic biology of HIV • describe HIV transmission routes • understand the importance of concurrent STIs in increasing risk of HIV transmission • discuss the natural history of HIV and list the major opportunistic infections that occur among AIDS patients in sub-Saharan Africa #1-3-3

  4. What You Will Learn, Cont. • By the end of this unit you should be able to: • describe the major elements of HIV prevention and control programmes • recognise that HIV is treated with antiretroviral drugs and that treatment involves prevention and treatment of opportunistic infections #1-3-4

  5. The Virus • HIV is a retrovirus that causes AIDS. • HIV attacks white blood cells (CD4+ lymphocytes and macrophages). • This weakens the immune system, which becomes unable to protect against opportunistic infections and certain types of cancers. #1-3-5

  6. HIV Types • Two major types of HIV have been recognised: HIV-1 and HIV-2 • The epidemiology of HIV subtype distribution and evolution worldwide are critical for several reasons: • For vaccine development • To trace transmission among individuals and track the spread of the virus through countries #1-3-6

  7. HIV-1 HIV-2 Geographic Distribution Worldwide Primarily confined to West Africa, although cases have been reported in Europe, Asia, and Latin America Subtypes Major group, M, is classified into 10 subtypes; additional divergent strains are known as group O Five genetic subtypes Natural History More easily transmitted than HIV-2, and faster progression to AIDS Less easily transmitted than HIV-1, and slower progression to AIDS Table 3.1. HIV-1 versus HIV-2 #1-3-7

  8. How HIV is Transmitted in Sub-Saharan Africa • Sexual Transmission (85%) • unprotected heterosexual intercourse • homosexual intercourse between men • there are no documented cases of sexual transmission between women • Blood and blood products (5%) • transfusion, clinical use of blood products, transplant • unsterile surgical and injection equipment • sharing syringes among drug users • Mother to child (10%) • during pregnancy • at delivery • through breast feeding #1-3-8

  9. Figure 3.1. Methods of HIV Transmission in Sub-Saharan Africa #1-3-9

  10. Increased Risk of Infection • Exposure • number of sexual partners • HIV-infected primary partner • Transmission • viral load of infected person • type of sexual contact (anal intercourse is riskier than vaginal; vaginal is riskier than oral) • co-existence of untreated STIs • non-use of barrier methods (condoms) #1-3-10

  11. Role of STIs • STIs may cause inflammation and ulceration, which increases the risk of acquiring infection by: • increasing recruitment of uninfected lymphocytes to the site of the inflammation • disrupting the genital epithelium and endothelium • Due to an immature cervix, adolescent women more easily acquire some STIs such as chlamydia. • The role of STIs in HIV transmission is illustrated by the Mwanza and Rakai/Masaka cases #1-3-11

  12. Natural History of HIV • In sub-Saharan Africa, median of 9 years from start of HIV infection to full-blown AIDS (without treatment). • In sub-Saharan Africa, death occurs usually less than one year after onset of AIDS (without treatment). • Very few with HIV avoid symptoms and death. • New ARV treatments have greatly extended life and reduced disease. #1-3-12

  13. Prevention of Sexual HIV Transmission • Decreasing the risk of being exposed • delay age of sexual debut • decrease the numbers of sexual partners • If exposed, decreasing the risk for transmission • consistently use male and female condoms • undergo voluntary testing and counselling, know your HIV status • treat STIs #1-3-13

  14. Method of transmission How to prevent transfusion • sterilising or not re-using needles • screening blood and blood products for HIV prior to administration re-use of needles and surgical instruments without sterilisation • sterilisation of surgical instruments (including those used in traditional practices such as scarification) • sterilising or not re-using needles needle stick injuries to healthcare workers • universal precautions for healthcare workers (for example, use of gloves and eyewear, proper disposal of needles) Table 3.2. Avoiding Blood-Borne Transmission of HIV #1-3-14

  15. Prevention of Mother-to-Child HIV Transmission • Short course antiretroviral treatment • Avoidance of breastfeeding • When replacement feeding is acceptable, feasible, affordable, sustainable and safe, avoidance of all breastfeeding by HIV-positive mothers is recommended. • Significant health risks are associated with using breast milk substitutes, however, including malnutrition and exposure to other infections. #1-3-15

  16. HIV/AIDS Treatment • Antiretroviral drugs are used to treat HIV infection. • nucleoside reverse transcriptase inhibitors (NRTIs) • non-nucleoside reverse transcriptase inhibitors (nNRTIs) • protease inhibitors (PIs) • Treatment will most likely start when patients develop clinical symptoms from their immunodeficiency or reach a CD4+ cell count of less than 350 cells per mm3. #1-3-16

  17. HIV/AIDS Treatment, Cont. • HIV treatment also includes diagnosis, prophylaxis and treatment of selected opportunistic infections • Anti-TB drugs • Cotrimoxazole prophylaxis can prevent the onset of some opportunistic infections. • Vaccines for some potential opportunistic infections, such as pneumococcal disease. #1-3-17

  18. In Summary • HIV is a virus that can be transmitted sexually, parenterally or perinatally. • Even so, there are precautions to prevent each type of transmission, including condom use, needle sterilisation and short course antiretroviral treatment during pregnancy. • Treatment includes antiretroviral drugs, and the prevention and treatment of opportunistic infections. #1-3-18

  19. Warm Up Review • Take a few minutes now to look back at your answers to the warm up questions at the beginning of the unit. • Make any changes you want to. • We will discuss the questions and answers in a few minutes. #1-3-19

  20. Answers to Warm Up Questions 1. Which body cells does HIV infect? a. respiratory cells b. skin cells c. red blood cells d. white blood cells #1-3-20

  21. Answers to Warm Up Questions 1. Which body cells does HIV infect? a. respiratory cells b. skin cells c. red blood cells d. white blood cells #1-3-21

  22. Answers to Warm Up Questions, Cont. 2. How many major strains of HIV exist? #1-3-22

  23. Answers to Warm Up Questions, Cont. 2. How many major strains of HIV exist? Two #1-3-23

  24. Answers to Warm Up Questions, Cont. 3. Which of the following is not a method of HIV transmission? a. sexual intercourse b. casual physical contact c. blood exchange d. mother to fetus #1-3-24

  25. Answers to Warm Up Questions, Cont. 3. Which of the following is not a method of HIV transmission? a. sexual intercourse b. casual physical contact c. blood exchange d. mother to fetus #1-3-25

  26. Answers to Warm Up Questions, Cont. 4. What type of infectious agent is HIV? a. bacterium b. virus c. prion d. none of the above #1-3-26

  27. Answers to Warm Up Questions, Cont. 4. What type of infectious agent is HIV? a. bacterium b. virus c. prion d. none of the above #1-3-27

  28. Answers to Warm Up Questions, Cont. 5. True or false? HIV infection and the onset of AIDS occur simultaneously. #1-3-28

  29. Answers to Warm Up Questions, Cont. 5. True or false? HIV infection and the onset of AIDS occur simultaneously. False #1-3-29

  30. Answers to Warm Up Questions, Cont. 6. Which region of the world has the greatest diversity of HIV subtypes, making the development of one unique treatment or vaccine difficult? #1-3-30

  31. Answers to Warm Up Questions, Cont. 6. Which region of the world has the greatest diversity of HIV subtypes, making the development of one unique treatment or vaccine difficult? Sub-Saharan Africa #1-3-31

  32. Answers to Warm Up Questions, Cont. 7. Which of the following is associated with increased risk of sexual transmission of HIV? a. failure to use a male or female condom b. a greater number of sexual partners c. a high viral load in an infected partner d. all of the above #1-3-32

  33. Answers to Warm Up Questions, Cont. 7. Which of the following is associated with increased risk of sexual transmission of HIV? a. failure to use a male or female condom b. a greater number of sexual partners c. a high viral load in an infected partner d. all of the above #1-3-33

  34. Answers to Warm Up Questions, Cont. 8. True or false? The presence of existing sexually transmitted infections increases the risk of acquiring HIV during sexual intercourse. #1-3-34

  35. Answers to Warm Up Questions, Cont. 8. True or false? The presence of existing sexually transmitted infections increases the risk of acquiring HIV during sexual intercourse. True #1-3-35

  36. Answers to Warm Up Questions, Cont. 9. List the three main types of antiretroviral drugs used to treat HIV infection. #1-3-36

  37. Answers to Warm Up Questions, Cont. 9. List the three main types of antiretroviral drugs used to treat HIV infection. • nucleoside reverse transcriptase inhibitors (NRTIs) • non-nucleoside reverse transcriptase inhibitors (nNRTIs) • protease inhibitors (PIs) #1-3-37

  38. Answers to Warm Up Questions, Cont. 10. Which of the following ultimately fatal opportunistic infections commonly occur(s) in AIDS patients? a. herpes zoster b. fungal infections c. tuberculosis d. all of the above #1-3-38

  39. Answers to Warm Up Questions, Cont. 10. Which of the following ultimately fatal opportunistic infections commonly occur(s) in AIDS patients? a. herpes zoster b. fungal infections c. tuberculosis d. all of the above #1-3-39

  40. Answers to Warm Up Questions, Cont. 11. True or false? A vaccine for the prevention of HIV infection is currently available. #1-3-40

  41. Answers to Warm Up Questions, Cont. 11. True or false? A vaccine for the prevention of HIV infection is currently available. False #1-3-41

  42. Answers to Warm Up Questions, Cont. 12. True or false? Some STIs such as chlamydia are biologically more easily acquired by young women, making them more susceptible to HIV infection. #1-3-42

  43. Answers to Warm Up Questions, Cont. 12. True or false? Some STIs such as chlamydia are biologically more easily acquired by young women, making them more susceptible to HIV infection. True #1-3-43

  44. Answers to Warm Up Questions, Cont. 13. Match the type of transmission with the percentage of infection that it accounts for (in sub-Saharan Africa): #1-3-44

  45. Answers to Warm Up Questions, Cont. 13. Match the type of transmission with the percentage of infection that it accounts for (in sub-Saharan Africa): #1-3-45

  46. Answers to Warm Up Questions, Cont. 14. ____________is the term used to describe the treatment to prevent or suppress infection. #1-3-46

  47. Answers to Warm Up Questions, Cont. 14. Prophylaxisis the term used to describe the treatment to prevent or suppress infection. #1-3-47

  48. Small Group Discussion: Instructions • Get into small groups to discuss these questions. • Choose a speaker for your group who will report back to the class. • Take 15 minutes for this exercise. #1-3-48

  49. Small Group Reports • Select one member from your group to present your answers. • Discuss with the rest of the class. #1-3-49

  50. Case Study: Instructions • Try this case study individually. • We’ll discuss the answers in class. #1-3-50

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