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Unit 1: Objectives and Approaches to HIV Surveillance

Learn about HIV surveillance terms, approaches, and objectives to monitor infection trends, risk factors, and transmission for public health action.

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Unit 1: Objectives and Approaches to HIV Surveillance

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  1. Unit 1: Objectives and Approaches to HIV Surveillance #3-1-1

  2. Warm Up Questions: Instructions • Take five minutes now to try the Unit 1 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. #3-1-2

  3. What You Will Learn • By the end of this unit you should be able to: • define the following terms: • HIV surveillance • second-generation HIV surveillance • HIV sero-surveillance • HIV sentinel surveillance • describe how epidemiologic principles, and also the state of the epidemic in a given location, guide HIV sero-surveillance #3-1-3

  4. What You Will Learn, Cont. • By the end of this unit you should be able to: • compare AIDS case surveillance and HIV sero-surveillance • identify the strengths and weaknesses of each • describe how the two are complementary • identify the main objectives of HIV sero-surveillance • describe the three main approaches to conducting HIV sero-surveillance #3-1-4

  5. What You Will Learn, Cont. • By the end of this unit you should be able to: • describe HIV incidence surveillance • identify other sources of HIV testing data that can be used for HIV surveillance, in the context of a second-generation HIV surveillance system #3-1-5

  6. Overview of HIV Surveillance • HIV surveillance is the systematic and regular collection of information on the occurrence, distribution and trends in HIV infection and factors associated with its transmission. • It monitors the risk of infection among specific populations • It is done on an on-going basis for the purpose of public health action #3-1-6

  7. Overview of HIV Surveillance, Cont. • There are two general approaches to HIV surveillance: • HIV case reporting • HIV sero-surveillance • Surveillance activities can either be active or passive. #3-1-7

  8. HIV Sero-Surveillance • The core HIV surveillance activity in the African region is HIV sero-surveillance. • HIVsero-surveillance is when you determine HIV prevalence by testing blood for HIV antibodies. • Sero-prevalence means prevalence estimates obtained through sero-surveillance • Surveys that collect blood for HIV or other tests (for example, syphilis) are called sero-surveys. #3-1-8

  9. HIV Sero-Surveillance, Cont. • HIV sero-surveillance data focus primarily on three factors: • Person • Place • Time #3-1-9

  10. Epidemiologic Principles Underlying HIV Sero-Surveillance • HIV infections are not uniformly distributed in a population. • There are a limited number of modes of HIV transmission • HIV infection enters into different geographic areas and populations at different times, and spreads at different rates. #3-2-10

  11. HIV Sentinel Surveillance • HIV sentinel surveillance is the main activity of HIV sero-surveillance, and includes: • Measuring the sero-prevalence of HIV infection in selected populations who are regularly seen at sentinel sites • Collecting demographic characteristics and some data on high-risk behaviours #3-2-11

  12. General Population Antenatal clinics Military conscription health intake centres High Risk Populations STI clinics Drug treatment centres Jails Tuberculosis (TB) clinics Hospital wards Sentinel Sites Represent the General Population or High-Risk Populations #3-2-12

  13. HIV Sero-SurveillanceObjectives • assess the prevalence of HIV infection in population sub-groups • monitor trends in the prevalence of HIV infection over time • identify behaviours and risk factors for HIV transmission #3-1-13

  14. HIV Sero-SurveillanceObjectives, Cont. • provide data to assist with public health decision-making • educate the public on HIV • guide scientific research • make estimates and projections #3-1-14

  15. HIV Sero-Surveillance Approaches • Clinic-based sero-surveys are cross-sectional surveys of persons seen at selected clinics or sites • Community-based sero-surveys may be needed to reach specific difficult-to-reach populations who are not included in clinic-based sentinel sites. • Population-based sero-surveys are designed to measure HIV prevalence in the general population directly. #3-1-15

  16. Sero-Surveillance Recommendations for Sub-Saharan Africa • Conduct HIV sentinel surveillance at ANCs. • Consider periodic community and population-based sero-surveys, and HIV sentinel surveillance at other sites. #3-1-16

  17. HIV Incidence and Prevalence • Prevalence measures the number of people with a given illness at a given time • Incidence refers to the number of new cases in a given period of time #3-1-17

  18. Incidence provides a measure of the speed of spread of HIV in a population indicates where HIV prevention is needed influenced by levels of infection and risky behaviours Prevalence a measure of the level of infection in a population provides a measure of current and future need for care influenced by both the rate of new infections (incidence) and the rate at which infected people leave the population HIV Incidence and Prevalence, Cont. #3-1-18

  19. Cohort studies Laboratory-based methods Repeat testers Mathematical modelling HIV prevalence in young age groups Measuring HIV Incidence #3-1-19

  20. Other Sources ofHIV Prevalence Data • Voluntary counselling and testing (VCT) programmes • Routine HIV testing • Blood transfusion safety checks • Scientific research • Screening of persons entering the military, seeking employment, or seeking other benefits #3-1-20

  21. Second-Generation HIV Surveillance • Second generation surveillance is a group of goals and principles for tracking the epidemic, including: • a focus on trends of the epidemic over time • a better understanding of the behaviours that drive the epidemic • emphasis on the sub-populations at highest risk for infection • better use of existing data • flexibility to the states of the epidemic #3-1-21

  22. Possible Sources of Data in Second Generation Surveillance • data collected from sero-surveys • data from behavioural surveys • AIDS case reporting • death registries • STI surveillance • TB surveillance #3-1-22

  23. AIDS case reporting HIV surveillance STI surveillance Behavioural surveillance Data management Data analysis and synthesis HIV estimates and projections Use of data for action Figure 1.1, Primary Components of Second-Generation HIV Surveillance *Monitoring and evaluation is on-going #3-1-23

  24. States of the Epidemic • Low-Level: HIV prevalence has not consistently exceeded 5% in any defined sub-population and remains below 1% in pregnant women in urban areas. • Concentrated: HIV prevalence is consistently over 5% in at least one defined sub-population but below 1% in pregnant women in urban areas • Generalized: HIV prevalence is consistently over 1% in pregnant women. #3-1-24

  25. AIDS Case Surveillance • AIDS case surveillance and HIV sero-surveillance are complementary • AIDS case surveillance describes the clinical disease burden caused by the HIV epidemic • There are several drawbacks to AIDS case reporting, due to the long latent period and, frequently, resource constraints. #3-1-25

  26. Integrated Disease Surveillance • WHO Regional Office for Africa (AFRO) recommends improving AIDS case reporting in the context of Integrated Disease Surveillance (IDS). • IDS is a system whereby all priority communicable diseases are reported together using the same form. #3-1-26

  27. Comparing AIDS Case Surveillance & HIV Sero-Surveillance #3-1-27

  28. Comparing AIDS Case Surveillance & HIV Sero-Surveillance, Cont. #3-1-28

  29. 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. #3-1-29

  30. Answers to Warm Up Questions • HIV sero-surveillance refers to the component of second-generation HIV surveillance that measures HIV prevalence. #3-1-30

  31. Answers to Warm Up Questions, Cont. • Which of the following is one of the epidemiologic principles that guide HIV surveillance? • HIV infections are not uniformly distributed in a population. • There are a limited number of ways that HIV can be transmitted. • HIV infection enters different areas and populations at different times, and spreads at different rates. • all of the above #3-1-31

  32. Answers to Warm Up Questions, Cont. • Because, ideally, blood donation is voluntary and measures to select donors at lowest risk of infection are in place, HIV prevalence data from blood banks are likely to under -estimate true prevalence in a population. #3-1-32

  33. Answers to Warm Up Questions, Cont. • True or false? In low level epidemics, HIV surveillance should primarily focus on measuring HIV prevalence in antenatal clinics. False #3-1-33

  34. Answers to Warm Up Questions, Cont. • True or false? Second-generation HIV surveillance is a single method of conducting HIV surveillance. False #3-1-34

  35. Answers to Warm Up Questions, Cont. • Which type of surveillance better describes the clinical disease burden of the HIV epidemic? • AIDS case surveillance • HIV sero-surveillance #3-1-35

  36. Answers to Warm Up Questions, Cont. • Because of the long latent period from HIV infection to the onset of AIDS, AIDS case surveillance may ________ the magnitude of the epidemic early on, when the HIV epidemic is expanding. • over-represent • under-represent #3-1-36

  37. Answers to Warm Up Questions, Cont. • Which of the following is an objective of HIV surveillance? • identifying sub-groups at greater or lesser risk for infection • monitoring trends in the prevalence of infection over time • assessing risk factors of HIV transmission • all of the above #3-1-37

  38. Answers to Warm Up Questions, Cont. • True or false? Sentinel surveys are harder to do than population-based surveys. They give more accurate picture of the over-all HIV prevalence in a population. False. #3-1-38

  39. Answers to Warm Up Questions, Cont. • Selection bias is especially a concern for sentinelsurveys, since people who choose to attend a particular facility may be different from those who do not use those sites. #3-1-39

  40. 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. #3-1-40

  41. Small Group Reports • Select one member from your group to present your answers. • Discuss with the rest of the class. #3-1-41

  42. Case Study: Instructions • Try this case study individually. • We’ll discuss the answers in class. #3-1-42

  43. Case Study Review • Follow along as we go over the case study in class. • Discuss your answers with the rest of the class. #3-1-43

  44. Questions, Process Check • Do you have any questions on the information we just covered? • Are you happy with how we worked on Unit 1? • Do you want to try something different that will help the group? #3-1-44

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