Acknowledgements
Appendix D, Answers to Warm-Up Questions and Case Studies
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Appendix D, Answers to Warm-Up Questions and Case StudiesAnswers are provided in italics for each unit’s warm-up questions and case study. Answers to the questions within the unit are not included. Unit questions are designed to stimulate small group discussion among participants in the workshop or class. Unit 1 AnswersWarm-up questions
True. UNAIDS estimates that 39.4 million adults and children were living with HIV/AIDS in 2004.
Sub-Saharan Africa. According to UNAIDS, the region is home to 64% of people living with HIV/AIDS worldwide.
The Caribbean is the second-most affected region in the world. In the Caribbean, AIDS is the leading cause of death among adults (15–44 years) and claimed an estimated 27 000 [18 000–37 000] lives in 2005.
Hispaniola Island, which includes Haiti and the Dominican Republic, is the epicentre of the HIV epidemic in the Americas.
In the Caribbean, the primary mode of sexual transmission has changed from being predominantly homosexual to being a mosaic of homo/bi and heterosexual epidemics. Heterosexual transmission accounts for the majority of HIV/AIDS cases in the Caribbean. Injecting drug use is responsible for a minority of HIV infections and only contributes significantly to the spread of HIV in Bermuda. Case study Cariba is a Caribbean nation that had its earliest cases of AIDS recognised in 1986. Data below are based on estimates of HIV prevalence by parish.
Arima. b. What are prominent recent trends? Prominent recent trends are: continued slow growth in St. Mary and Arima, levelling off or decrease in Kingstown and Yotown and rapid growth in St. James.
St. James. The epidemic is increasing rapidly. Unit 2 Answers Warm-up questions
HIV infects white blood cells, which are involved with protecting the body against infection as part of the immune system. These include lymphocytes and macrophages. 2. How many major strains of HIV exist? Two: HIV-1 and HIV-2.
HIV transmission is transmitted through body fluids, not through casual physical contact.
HIV is a virus. HIV stands for ‘human immunodeficiency virus.’
True False False. AIDS is characterised by the clinical appearance of symptoms. It can occur years after the initial HIV infection.
Sub-Saharan Africa has the greatest diversity of HIV sub-types. This region has not only the highest HIV prevalence levels, but also the greatest diversity of sub-types, making treatment especially difficult. Warm-up questions, continued
The failure to use a condom allows the virus to pass more easily from an infected to an uninfected person. The more sexual partners an individual has, the higher the risk that the one of them is infected with HIV. A greater amount of virus in the bodily fluids increases the chances that the virus will be transmitted to the uninfected partner.
True False True. The inflammation and ulceration caused by existing STIs makes it easier for HIV to enter the body.
AIDS patients have weaker immune systems, making it easier for the patients to acquire these opportunistic infections.
True False False. While vaccines are being researched and may be available many years in the future, currently there is no HIV vaccine.
True False Warm-up questions, continued True. Because of their more fragile vaginal walls, young women are more likely to be infected.
Prophylaxis helps to prevent opportunistic infections from developing in patients with HIV infection. Case study Cariba has experienced rapid expansion of the HIV epidemic. Prevention programmes to date have focused primarily on prevention of mother-to-child transmission. Examine the data and answer the questions. Incidence of various STIs over time, Cariba.
* Cases per 1000, population 15-49 years a. Do you think that sexually transmitted infections (STIs) may be playing an important role in the spread of HIV infection? Why? Yes, it is likely that STIs are playing a major role in the spread of sexually transmitted HIV in Cariba. It’s likely that STIs are important in HIV transmission because:
This is a classic exponential growth phase and similar to the situation in Mwanza, Tanzania, where STI control was able to show an effect on HIV incidence. b. Would an STI prevention programme be an important part of the country’s HIV control efforts? Yes, these data suggest that a situation similar to that in Mwanza, Tanzania exists in Cariba. An enhanced STI control programme may be critical to decreasing HIV incidence. Warm-up questions, continued c. Given the HIV incidence in Cariba, what do you think will happen to tuberculosis rates in the next several years, and why? Tuberculosis (TB) rates will likely increase as the HIV epidemic spreads. TB cases will involve both the appearance of active tuberculosis among persons already infected with TB, and transmission of TB from HIV-infected persons to those with and without HIV infection. Unit 3 Answers Warm-up questions
Prevalence is a measure of disease burden in a given population, while sensitivity and negative predictive value are terms used to describe the validity of case definitions.
True False False. Surveillance systems involve ongoing collection and analysis of data, not a one-time survey.
Incidence is the rate at which disease burden is increasing in a particular population, while specificity and positive predictive value are terms used to describe case definitions. Unit 4 Answers 4.1 Warm-up questions 1. What are the key differences between HIV sero-surveillance and HIV case reporting? HIV sero-surveillance refers to the component of second-generation HIV surveillance that measures HIV prevalence. HIV sero-surveillance measures HIV prevalence in specific populations on a regular basis using sero-surveys. HIV case reporting refers to the process of reporting the names or codes of persons with confirmed HIV positive status to surveillance staff.
True False True. HIV testing of women attending antenatal clinics has been the most frequently used data for prevalence estimates.
AIDS has a long latent period before symptoms are clinically apparent. Advanced HIV disease/AIDS case reporting does not measure incidence of HIV infection.
4.1 Warm-up questions, continued
Special laboratory tests are required to detect HIV incidence. The BED assay is a promising technique to measure HIV incidence in a single blood specimen. The BED assay identifies persons who were infected in the last 160 days (or nearly six months.) 4.1 Case study 1. You are the parish surveillance officer in Cariba, which is estimated to have one of the highest prevalence rates of HIV in the region. The national AIDS control programme is interested in expanding and improving its surveillance programme, and the national surveillance officer is conducting site visits to various parishes to discuss ways of improving surveillance. During your meeting with the national surveillance officer, you are asked to suggest additional surveillance activities in your parish that you believe could be implemented successfully. Describe the activities you would suggest. Additional surveillance activities that could be successfully implemented to expand the AIDS control programme surveillance system include: using data from HIV testing and prevention of mother-to-child programmes to count asymptomatic HIV cases; using data from treatment and care programmes to supplement HIV case surveillance data.
Antiretroviral treatment programme data can provide patient monitoring data. Data from ART programmes can also be used to measure the effectiveness of treatment programmes and other interventions. For efficient use of time and resources, those programmes that serve the largest number of HIV-infected persons should be targeted for assisting with case reporting. 4.2 Warm-up questions
True False True. The revised (2006) adult and paediatric WHO HIV clinical staging systems both include four clinical stages, with stage 1 representing early disease and stage 4 representing late-stage disease (AIDS). For surveillance purposes, stages 3 and 4 meet the criteria for reporting.
True False False. Adults and infants may have different clinical manifestations of advanced HIV disease. Also, serologic evidence of immuno-suppression differs between adults and infants. Brief case definitions of advanced HIV disease are provided below. For adults, the case definition for advanced HIV disease is: A positive HIV antibody test AND EITHER Any clinical stage 3 or stage 4 disease OR Where CD4 testing is available, any clinical stage and CD4 count < 350 cells/mm3. For infants, the case definition for advanced HIV disease is: The presence of HIV infection AND EITHER Any clinical stage 3 or stage 4 disease OR Where CD4 testing is available, any clinical stage with CD4 <20% TLC in children aged 12-59 months.
WHO recommends that countries standardise their reporting practises. Countries may:
4.2 Warm-up questions, continued
True False The revised case definitions include both presumptive clinical diagnoses that can be made in the absence of sophisticated laboratory tests and definitive clinical criteria that require confirmatory laboratory tests.
True False True. Prior to 1994, the WHO had not developed a surveillance case definition for HIV disease alone (that is, persons who have HIV infection but who do not meet the surveillance case definition of AIDS). Unit 4.2 Case study
Processes to ensure that HIV surveillance is standardised include:
Unit 4.2 Case study, continued
If CD4 testing is available, ART can begin at WHO clinical stage 4 (AIDS) regardless of the CD4 count, at WHO clinical stage 3 in patients whose CD4 count is <350 cells/mm3 or in patients with WHO clinical stages 1 or 2 when the CD4 count is < 200 cells/mm3.
If CD4 testing is not available, a total lymphocyte count ≤1200 cells/ mm3 can be used as an indication of immunodeficiency that is severe enough to begin ART. Unit 4 Final case study You are the new HIV programme director in Cariba. Cariba has conducted antenatal sero-surveillance for many years and the results from those surveys have been used to estimate the HIV prevalence in the country. The prevalence in young adults in Cariba is estimated to be 3% in urban areas. HIV case reporting has been recommended, but only a few facilities have reported HIV cases. Because of the high HIV prevalence, it is assumed that the prevalence of AIDS is also very high. Cariba has received additional resources that are to be used for providing HIV-infected patients with ART. Because of its high prevalence, Yotown County, which has a large urban area, has been selected as a site to offer ART. The provision of ART to HIV-infected patients is co-ordinated by your colleague (Dr. MB) at the Ministry of Health in Cariba. To begin planning for treating patients you set up a meeting with Dr. MB. Together you decide that the initial focus should be on conducting reporting of persons with advanced HIV disease. How would you go about doing this? In order to determine the number of patients who will need ART, you will need to know the number of patients with advanced HIV disease. (HIV clinical stages 3 and 4.) The clinical/immunological criteria for diagnosing a person with advanced HIV disease are as follows: Unit 4 Final case study, continued
Reporting should be done at the time the person is initially diagnosed with advanced HIV disease. You and Dr. MB must make decisions regarding how ART should be provided in Yotown Parish. You both agree to follow the WHO treatment guidelines. What are the WHO criteria for initiating ART? The best time to begin antiretroviral treatment can be determined using clinical staging and, if available, CD4 counts/percents. The WHO antiretroviral treatment recommendations for adults and adolescents are as follows:
Unit 4 Final case study, continued You and Dr. MB decide to offer ART at three clinics and at the medical college in Yotown Parish. How will this affect your plans for advanced HIV disease case reporting? The link between staging, ART use and case reporting is useful for surveillance purposes. HIV case reporting is generally done by healthcare providers, usually from hospitals and clinics that provide ART. Therefore, patients who are receiving care at these facilities will have their clinical stage determined. The clinical/immunological criteria for diagnosing advanced HIV disease correspond to the clinical/immunological criteria for initiating ART. What are some initial steps that should be taken prior to offering ART? Prior to offering ART, treatment protocols should be developed; methods to record patient treatment information should be determined; and staff should be trained. Use of WHO methods is recommended. What are the outcomes that you think should be monitored in order to evaluate the impact that ART is having on patients with HIV? In order to determine how well the programme is working, you will need to monitor how many patients initiate ART, what regimens they are receiving, and adherence. To measure the impact that treatment is having, it is best to monitor the development of new opportunistic illnesses and death. Effective treatment programmes should result in declines in both of these. What methods can be used to measure the impact of ART on mortality? Ideally, there would be existing mortality data that could be used. If these are not available, then it is worthwhile to develop methods of obtaining census data, deaths, and causes of death using verbal autopsy methods. Unit 5 Answers Warm-up
questions
In order to describe the condition under surveillance, the surveillance system must be able to describe the condition by the following attributes: person, place and time.
To report the timeliness of case reporting you can use:
Case study St. James Parish is in the coastal area of Cariba and has the country’s major port city. A British university has been conducting studies of commercial sex workers in the port city for nearly a decade. For the last five years, they have been conducting serial sero-prevalence surveys for HIV and syphilis.
The first step in evaluating these special studies would be to meet with study staff members and Ministry of Health personnel. The people conducting the special studies and/or the Ministry of Health may want to define the questions to be addressed by the Case study, continued surveillance system evaluation. They may also want to decide how to use the findings from the evaluation.
As the Ministry of Health is deciding whether or not to take over sponsorship of the studies and include them in the provincial sentinel surveillance system, a possible focus of the evaluation would be to assess how the system can detect and report HIV and syphilis among sex workers and to assess the quality of the epidemiologic information produced.
In a comprehensive evaluation, the simplicity, flexibility, data quality, acceptability, sensitivity, positive predictive value, representativeness, timeliness and stability of the surveillance system should be assessed. CAREC recommends that member countries evaluate the completeness (sensitivity), timeliness and validity of surveillance systems on an annual basis.
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