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Module 1: Overview of HIV Infection

Module 1: Overview of HIV Infection. Unit 2: Epidemiology of HIV Infection. Objectives. At the end of this session the participant should be able to: Describe the history of HIV Explain the global, regional, national and local distribution of HIV

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Module 1: Overview of HIV Infection

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  1. Module 1:Overview of HIV Infection Unit 2: Epidemiology of HIV Infection

  2. Objectives At the end of this session the participant should be able to: • Describe the history of HIV • Explain the global, regional, national and local distribution of HIV • Discuss the distribution of HIV by age and sex • Discuss changes in morbidity and mortality due to HIV/AIDS • Define different modes of HIV transmission • Discuss factors that facilitate HIV transmission-biological and social

  3. Historical background • 1981 - doctors in US recognized PCP in homosexual males, a condition previously unreported in healthy adults • Later recognized that patients all were immunosuppressed • 1983/4 - scientist described the cause of the syndrome as a retrovirus • Lymphadenopathy Associated Virus (LAV) • AIDs Associated Retrovirus (ARV) • Human T-lymphotrophic Virus Ш (HTLV-Ш) • In Kenya the first case described in 1984 • 1986 - Human Immunodeficiency Virus (HIV) accepted as international designation for the retrovirus in a WHO consultative meeting

  4. Fourth biggest killer in the world Estimated 40 million living with HIV by end of 2004 About one-third of PLHA are between 15-24 years Most people are still unaware they are infected Young women are more vulnerable Epidemic Update: Global Picture

  5. Adults And Children Estimated To Be Living With HIV As Of End 2004 Western & Central Europe 610 000 [480 000 – 760 000] Eastern Europe & Central Asia 1.4 million [920 000 – 2.1 million] North America 1.0 million [540 000 – 1.6 million] East Asia 1.1 million [560 000 – 1.8 million] North Africa & Middle East 540 000 [230 000 – 1.5 million] Caribbean 440 000 [270 000 – 780 000] South & South-East Asia 7.1 million [4.4 – 10.6 million] Sub-Saharan Africa 25.4 million [23.4 – 28.4 million] Latin America 1.7 million [1.3 – 2.2 million] Oceania 35 000 [25 000 – 48 000] Total: 39.4 (35.9 – 44.3) million Source: UNAIDS 2004 Report on the Global AIDS Epidemic

  6. Epidemic Update: Sub-Saharan Africa (SSA) End 2004 Total number of people living 25.4 million with HIV/AIDS (60% of total disease burden) People newly infected 3.1 million with HIV/AIDS AIDS death in 2004 2.3 million Adult prevalence 7.4%

  7. Updates HIV/AIDS in Kenya

  8. Population based National HIV data (KDHS 2003) • National HIV prevalence: 7% • Women more likely to be HIV positive than men (8.7% vs 4.5%) • Age peak of HIV prevalence differs by sex: female 25-29 y; male 35-44 y • Urban HIV prevalence: 10%; Rural HIV prevalence: 6% • Highest prevalence in Nyanza: 14%, followed by Nairobi: 9.1% • All other provinces are below the national level

  9. Impact of HIV on Morbidity and Mortality Secondary to Other Infections • People with HIV/AIDS are susceptible to other infections • Due to lowered immunity • High HIV prevalence increases the pool of people with suppressed immunity • Other infectious conditions within such a population find a highly susceptible group of people. • HIV infected people have rates of both TB and LRTI much higher than the HIV negative

  10. HIV Transmission • Modes of Transmission • Biological Factors Affecting Transmission • Socio-economic Factors Facilitating Transmission

  11. Modes of Transmission • Sexual contact most important mode of transmission/acquisition of HIV worldwide • In Africa mainly heterosexual (male female) • Includes homosexual (men having sex with men) as well • Non-consensual sexual exposure (assault) • Parenteral • Transfusion of infected blood or blood products • Exposure to infected blood or body fluids through contaminated sharps- IDU through needle-sharing or needle stick accidents • Donated organs • Traditional procedures • Perinatal • Transplacental, during labor/delivery and breastfeeding • HIV is not transmitted by casual contact, surface contact, or from insect bites

  12. Percent infection by transmission route….

  13. Biological Factors Influencing HIV Transmission • Disease status of source patient • Related to degree of immunosuppression and viral load • High risk during primary infection and late disease when viral load high • Also higher the lower the CD4 count, independently of viral load • Presence of untreated STIs in source and person at risk • Both ulcerative and non ulcerative STIs important cofactors • Related to high viral load in genital secretions during STIs and the disturbance of the genital mucosa • A major reason for high prevalence in SSA

  14. Biological Factors Influencing HIV Transmission • Circumcision status • Uncircumcised men 2x as likely to acquire HIV infection than circumcised. Also more likely to acquire STIs • Gender differences in susceptibility • Female genital anatomy presents a larger surface area with more of the cells that HIV requires to gain entry • (Socio-cultural factors) • Host genetic differences

  15. Socio-economicFactors Facilitating HIV Transmission • Social Mobility • Global Economy • HIV/AIDS follows routes of commerce • Partners living apart • Stigma and Denial • Denial and silence is the norm • Stigma prevents acknowledgment of problem and care-seeking • People in Conflict • Context of war and struggle of power spreads AIDS • Cultural Factors • Traditions, beliefs, and practices affect understanding of health and disease and acceptance of conventional medical treatment

  16. Socio-economicFactors (cont’d) • Gender • In many cultures it is accepted for men to have many sexual relationships • Women suffer gender inequalities • Many women unable to negotiate condom use • Poverty • Lack of information needed to understand and prevent HIV • Drug Use and Alcohol Consumption • Impaired judgment • Sharing of needles and equipment

  17. Behavioral Factors • Multiple sexual partners • Unprotected sexual intercourse • Large age difference between sexual partners

  18. Factors not associated with risk of transmission • Insect bites • Saliva (kissing) • Sneezing or coughing • Skin contact (e.g. hugging) • Shared use of facilities (e.g. toilets)

  19. Summary • HIV has become a pandemic since the first cases were identified over 2 decades ago • It is a major cause of morbidity and mortality in many countries particularly in sub-Saharan Africa • Many factors contribute to HIV transmission in a society • Many are modifiable allowing for prevention strategies • Knowledge of these factors can be used to design control strategies.

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