![HIV/AIDS
Introduction and Epidemiology
Mpondo B [MD., MMED., DTM&H]](https://image.slidesharecdn.com/hivintroductionandepidemiology-241125124544-190216f5/85/HIV-Introduction-and-Epidemiology-ppt-1-320.jpg)
HIV Introduction and Epidemiology.ppt,,,
- 1. HIV/AIDS Introduction and Epidemiology Mpondo B [MD., MMED., DTM&H]
- 2. What Is HIV? HIV (human immunodeficiency virus) is a virus that attacks cells that help the body fight infection, making a person more vulnerable to other infections and diseases If left untreated, HIV can lead to the disease AIDS (acquired immunodeficiency syndrome)
- 3. What Is AIDS? AIDS is the late stage of HIV infection that occurs when the body’s immune system is badly damaged because of the virus A person with HIV is considered to have progressed to AIDS when: • the number of their CD4 cells falls below 200 cells per cubic millimeter of blood (200 cells/mm3 OR • they develop one or more opportunistic infections regardless of their CD4 count
- 4. History 1981…First Reported Case of AIDS 1982…First Use of “AIDS” Acronym 1983…First reported case in Tanzania 1984…Causative Agent Identified 1985…First HIV Antibody Test 1986…First Use of “HIV” Acronym 1987…First Medication
- 5. HIV Origin Where did the virus come from?
- 7. Introduction Human immunodeficiency virus (HIV) is a blood-borne, sexually transmissible virus The virus is typically transmitted via sexual intercourse, shared intravenous drug paraphernalia, and mother-to-child transmission (MTCT)
- 8. The most common route of infection varies from country to country and even among cities Co-infection with other viruses that share similar routes of transmission is common
- 9. HIV types Two distinct species of HIV o HIV-1 o HIV-2 Each is composed of multiple subtypes, or clades All clades of HIV-1 tend to cause similar disease, but the global distribution of the clades differs
- 10. HIV-1 is distributed worldwide, HIV-2 is mainly present in West Africa Infection with HIV-2 causes slower disease progression and is more benign than infection with HIV-1
- 11. HIV-1 is further divided into three groups o group M (main group, >98%) o group O (outlier, <1%) o group N (new, <1%) Group M is responsible for the majority of HIV-1 infections worldwide
- 12. Subtypes /Clades HIV has subtypes: A-K (excluding I) Circulating recombinant forms (CRFs)
- 13. G
- 14. Source of infection HIV-1 probably originated from one or more cross-species transfers from chimpanzees in central Africa HIV-2 is closely related to viruses that infect sooty mangabeys in western Africa Genetically, HIV-1 and HIV-2 are superficially similar, but each contains unique genes and its own distinct replication process
- 15. Virulence HIV-2: o carries a slightly lower risk of transmission o tends to progress more slowly to acquired immune deficiency syndrome (AIDS) Persons infected with HIV-2 tend to have lower viral load
- 16. Virology of HIV HIV-1 and HIV-2 are retroviruses in the Retroviridae family, Lentivirus genus. They are: o enveloped o diploid o single-stranded positive-sense RNA
- 17. Viral structure Basic components: I. An outer membrane II. A protein shell III.Enzymes IV.RNA
- 19. Viral entry into the cell & lifecycle
- 20. Natural history of HIV Phases of HIV infection: o Acute HIV Infection (acute seroconversion) o Chronic HIV Infection (asymptomatic infection/clinical latency) o AIDS
- 22. HIV disease progression Normal progressors Rapid progressors Slow progressors
- 23. How does HIV cause AIDS???? Any answers?
- 24. WHO HIV Clinical Staging FOUR Clinical stages: • Stage 1 – Asymptomatic • Stage 2 – Mild • Stage 3 – Advanced • Stage 4 – Severe
- 25. WHO Clinical Staging System (1) The WHO Clinical staging system is based on clinical features that have prognostic significance resulting in four stages of disease progression WHO staging is done where HIV infection is confirmed by HIV antibody or virological markers
- 27. Correlation Between WHO Clinical Staging and CD4 Count WHO 1 WHO 2 WHO 3 WHO 4
- 31. HIV Regional prevalence in Tanzania (THIS 2016/2017)
- 32. Trend of HIV
- 34. Racial, sexual, and age-related differences in incidence: In the developed world, HIV infection is much more common in males; in the developing world in males and females Young adults tend to be at higher risk of acquiring HIV Children may become infected by transplacental transmission or by breastfeeding
- 35. HIV transmission Risks of transmission: o Unprotected sexual intercourse o A large number of sexual partners o Previous or current sexually transmitted infections (STIs) o Sharing of intravenous (IV) drug paraphernalia o Receipt of blood products o Mucosal contact with infected blood or needle-stick injuries o Maternal HIV infection (for newborns, infants, and children)
- 37. Vulnerable groups Men who have sex with men (MSM) Young men who have sex with men (YMSM) Sex workers People who inject drugs (PWID) Prisoners Women Transgender people Children Orphaned children
- 38. 38
Editor's Notes
- #24: EMPHASIZE that WHO clinical staging of HIV disease should only be used once HIV infection has been confirmed (serological and/or virological evidence of HIV infection). REFER participants to Handout 2.2.4 WHO Clinical Staging in Adults, Adolescents and Children on page 173 in the Participant Handbook.
- #25: EMPHASIZE that WHO staging is done where HIV infection is confirmed by HIV antibody or virological testing. WHO HIV staging can be used in the absence of other immunological markers, as staging relies on the presentation of clinical features. Clinical staging can be used effectively without access to CD4 or other laboratory testing. However, CD4 testing is useful for determining the degree of immunocompromise, and where CD4 facilities are available they should be used to support and reinforce clinical decision-making. EMPHASIZE that CD4 levels are not necessary for starting ART but if available they are useful for knowing the degree of damage to the immune system and knowing the point at which treatment was initiated.
- #27: REFER participants to Handout 4.2.1: WHO Clinical Staging of HIV/AIDS for Adults and Adolescents with Confirmed HIV Infection on Page 131. EXPLAIN this chart to participants, noting where various OIs fall in different stages. For each WHO category, let participants mention all possible OIs.