1. Module 1 Unit 2: Epidemiology of HIV

2. Objectives At the end of this session, the participant should be able to: 1. Describe the history of HIV 2. Explain the global, regional and national/local distribution of HIV 3. Discuss the distribution of HIV by age and sex 4. Discuss changes in morbidity and mortality due to HIV/AIDS 5. define different modes of HIV transmission 6. Discus factors that facilitate HIV transmission-biological and social

3. Historical background 1981 - doctors in US recognized a previously unseen syndrome (PCP) in homosexual males Later recognized that they were all immune suppressed 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 1 st case described in 1984 1986 - HIV accepted as international designation for the retrovirus in a WHO consultative meeting

4. Epidemic Update: Global Picture Fourth biggest killer in the world Estimated 40 million living with HIV by end of 2003 About one-third of PLHA are between 15-24 years Most people are unaware they are infected Young women are more vulnerable

5. Adults and children estimated to be living with HIV/AIDS as of end 2003 Total: 34 – 46 million Western Europe 520 000 – 680 000 North Africa & Middle East 470 000 – 730 000 Sub-Saharan Africa 25.0 – 28.2 million Eastern Europe & Central Asia 1.2 – 1.8 million South & South-East Asia 4.6 – 8.2 million Australia & New Zealand 12 000 – 18 000 North America 790 000 – 1.2 million Caribbean 350 000 – 590 000 Latin America 1.3 – 1.9 million East Asia & Pacific 700 000 – 1.3 million

6. Global summary of the HIV/AIDS epidemic, December 2003 The ranges around the estimates in this table define the boundaries within which the actual numbers lie, based on the best available information. These ranges are more precise than those of previous years, and work is under way to increase even further the precision of the estimates that will be published mid-2004. Number of people living with HIV/AIDS Total40 million (34 – 46 million) Adults37 million (31 – 43 million) Children under 15 years2.5 million (2.1 – 2.9 million) People newly infected with HIV in 2003 Total5 million (4.2 – 5.8 million) Adults4.2 million (3.6 – 4.8 million) Children under 15 years700 000 (590 000 – 810 000) AIDS deaths in 2003Total3 million (2.5 – 3.5 million) Adults2.5 million (2.1 – 2.9 million) Children under 15 years500 000 (420 000 – 580 000)

7. Epidemic Update: Sub-Saharan Africa  HIV is now the leading cause of death  25.0 – 28.2 million living with HIV infection by end of 2003  10-15% of need ARV  Estimated 3-3.4 million new HIV infections in 2003  70% found in sub Saharan Africa  10% (600 million) of world’s population live in sub Saharan African  By 2010, an estimated 106 million children under age 15 will have lost one or both parents, with 25 million of this group orphaned due to HIV/AIDS

8. Updates HIV/AIDS in Kenya IndicatorNASCOP 2003 National adult prevalence - 15-49 years7% Number adults infected1,100,000 Number children infected150,000 Number needing ARV 200,000

9. Impact on Morbidity and mortality of 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 Any other infectious condition within such population (e.g.TB) therefore finds a highly susceptible group of people.

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

12. Modes of Transmission Sexual contact Male-to-female, female-to-male, male-to-male, and female-to-female Parenteral Blood transfusion of infected blood or blood products Exposure to infected blood or body fluids- IDU through needle-sharing or needle stick accidents Donated organs Perinatal Transplacental, during labour/delivery and breastfeeding Worldwide, sexual transmission is the predominant mode HIV cannot be transmitted by casual contact, surface contact, or from insect bites

13. Percent infection by transmission route…. Transmission route% Sexual intercourse70-80 Mother-to-child-transmission5-10 Blood transfusion3-5 Injecting drug use5-10 Health care – eg: needle stick injury<0.01

14. Biological factors influencing HIV transmission Stage of HIV infection: High riskduring primary infection (weeks) Lower when asymptomatic (several years) Rises as immune function deteriorates and viral load increases (months to years) Presence of untreated ulcerative STIs A major reason for high prevalence in SSA Gender differences in susceptibility

15. Socio-economic Factors Facilitating Transmission  Social Mobility  Global Economy  HIV/AIDS follows routes of commerce  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-economic Factors (cont’d) Gender In many cultures men are expected 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. Factors not associated with risk of transmission insect bites Saliva sneezing or coughing skin contact (e.g. hugging) shared use of facilities (e.g. toilets)

18. Summary HIV has spread worldwide after its discovery It is a major cause of morbidity and mortality in many countries Many factors contribute to HIV transmission in a society Knowledge of these factors can be used to design control strategies.