Introduction to HIV Case Surveillance

Introduction to HIV Case Surveillance

What you

By the end of this unit, you should be able to:

• 
  describe the stages in the natural history of HIV disease that are important for surveillance purposes
  
• 
  describe the primary purposes of conducting HIV case surveillance
  
• 
  describe the differences between HIV case surveillance, advanced HIV disease case surveillance, AIDS case surveillance and HIV sero-surveillance
  
• 
  list four types of HIV-related programmes that can report cases to an HIV case surveillance system.
  

HIV and target points

for surveillance

HIV infection produces a disease that lasts for many years. Shortly after becoming infected, an individual may experience signs and symptoms of this initial infection (called primary HIV infection). These signs and symptoms may include fever, muscle aches and swollen glands. Often these symptoms go unnoticed by the infected person. Some people do not experience any symptoms or signs of primary HIV disease.

• 
  Prior to antiretroviral therapy (ART), the average time from HIV infection to onset of clinical AIDS in North American patients was 10 years.
  

• 
  Without ART, the duration between HIV infection and onset of AIDS is shorter in developing countries than in North America.
  

The advent of effective ART has considerably reduced the rate of progression to AIDS in areas where these drugs are available. It has also been associated with changes in the types of opportunistic infections that appear with AIDS.

• 
  HIV incidence (that is the number or rate of new HIV infections)
  
• 
  HIV prevalence (that is the number or rate of all persons living with HIV during a specified time period, regardless of how long they have been infected or whether or not they are aware of their infection)
  
• 
  The incidence of advanced HIV disease (or AIDS)
  
• 
  The prevalence of advanced HIV disease (or AIDS)
  
• 
  Deaths from advanced HIV disease (or AIDS).
  

Measuring each of these points in the course of HIV disease provides for a complete HIV surveillance system. These data can be used to determine the need for prevention or medical interventions and to assess of the impact of such programmes. However, in resource-constrained settings, it is often difficult to include all of these target points in the surveillance system. In those areas where not all of these points can be counted, efforts should be made to obtain information on as many of these as possible.

Obtaining an accurate and complete count of persons with advanced HIV disease/AIDS is important as a way to anticipate need for medical care and other support services. These data can also be used as a measure of the success of treatment of HIV disease at earlier stages. In countries where ART is becoming increasingly available, the number of persons with advanced HIV disease/AIDS should decline, even in the face of ongoing HIV transmission.

Deaths from AIDS have dropped dramatically in countries where antiretroviral treatment has been widely used. Thus, tracking deaths from advanced HIV disease/AIDS is an important measure of the success of treatment programmes. In addition, understanding the proportion of deaths from HIV-related disease and the age groups most severely affected is an important measure of the magnitude of the problem. However, in order to accurately count and track trends in HIV-related deaths, countries must have well-functioning vital statistics registries. Alternative methods for mortality surveillance exist and can be used in countries in which vital statistics registries need major strengthening.

AIDS case

surveillance

In 1981, surveillance began for a newly recognised constellation of diseases now known as AIDS. AIDS has been characterised by a set of diseases (called AIDS-defining opportunistic illnesses).

The initial WHO AIDS case definition (Bangui) was based entirely on the presence of AIDS-defining illnesses. However, as HIV testing became available in developing countries, the WHO AIDS case definition was expanded in 1994 to include serologic results. In some countries, the expanded case definition has not been used consistently because of:

• 
  inadequacy of HIV testing reagents
  
• 
  poor laboratory infrastructure
  
• 
  lack of training of health personnel
  
• 
  lack of quality control procedures.
  

for HIV case

surveillance

ART has dramatically altered the natural history of HIV disease. Antiretroviral medications delay progression from HIV disease to the advanced stages of HIV disease and reduce HIV-related mortality. In fact, one measure of the success of ART programmes is an unchanging (or increasing) HIV prevalence with a concurrent decrease in AIDS incidence and HIV-related deaths.

• 
  to provide a complete count or estimate of the number of persons with HIV infection
  
• 
  to measure the effectiveness of treatment programmes and other interventions.
  

Several factors must be in place for an HIV case surveillance system to work. These are:

• 
  people at risk for HIV infection must be tested
  
• 
  people must feel that there is a benefit to getting an HIV test
  
• 
  people who are receiving HIV tests must feel that their privacy will be protected.
  

Outputs of

HIV case

surveillance

Accurate, timely and complete information on persons with HIV infection is required to:

• 
  determine the burden of disease attributable to HIV in the country/region
  

• 
  assess trends in incidence and prevalence of HIV infection and disease
  
• 
  determine the burden and impact of HIV on health services
  
• 
  provide information on the opportunistic infections associated with advanced HIV disease
  
• 
  determine the characteristics and risk factors (transmission categories) of persons with HIV infection
  
• 
  use data from HIV surveillance for:
  
  • 
    advocacy
    
  • 
    resource mobilisation and allocation
    
  • 
    programme planning for prevention, support, care and treatment
    
  • 
    targeting interventions to appropriate sub-populations
    
  • 
    monitoring and evaluation.
    

Surveillance

terminology

It is important to note that HIV case surveillance is not the same thing as HIV sero-surveillance. These systems have different goals and different uses; they are complementary, not competing. A complete surveillance system will have both. Table 4.2 explains HIV surveillance terminology.

HIV sero-surveillance (also called HIV sero-prevalence)	measures the prevalence of HIV infection using serological survey methods does not report on individual patients
HIV case surveillance	reports persons diagnosed with HIV infection, regardless of clinical stage or immunological status

Discussing

the table

Looking at Table 4.2, answer the following questions:

1. 
   Which clinical stages are included in HIV case surveillance?
   

2. 
   What is one difference between HIV case surveillance and HIV sero-surveillance?
   

• 
  as a source of information for the completion of HIV case surveillance reports
  
• 
  as a source of data to supplement HIV case surveillance data and data from HIV sero-prevalence surveys in annual HIV/AIDS epidemiological profiles and other such reports.
  

Programme data can provide information for HIV case surveillance if:

• 
  programmes collect and retain patient-level information
  
• 
  systems are in place (at facilities that do HIV diagnosis) to record that cases have been reported to the surveillance programme
  
• 
  programme staff are trained on how to report cases and have access to case surveillance forms (passive surveillance method) or surveillance officers provide assistance in completing case report forms (active surveillance).
  

In addition, case reporting is more likely to occur if surveillance officers:

• 
  meet with programme managers to discuss the importance of case surveillance, provide case surveillance forms and conduct training
  
• 
  adequately assure the security and confidentiality of case information (particularly if cases are reported using patient names)
  
• 
  provide regular feedback to the healthcare workers/providers regarding the results from case surveillance.
  

Supplemental programme monitoring data may be obtained from:

• 
  voluntary counselling and testing sites: data on numbers tested and percent HIV-infected
  
• 
  programmes for prevention of HIV transmission from mother to child: data on number of women tested, percent positive, percent of positives provided with ART, percent of babies tested for HIV, percent of babies with HIV infection
  
• 
  care and treatment programmes: data on persons receiving HIV support, care and ART treatment, data on survival time after start of treatment, early warning indicators for emergence of HIV drug resistance, etc.
  
• 
  services for orphans and vulnerable children.
  

review

discussion

Get into small groups to discuss these questions.

1. 
   Which AIDS case definition has been used in your country, the Bangui definition, the WHO expanded case definition or something else? Discuss the utility of this case definition. Has it undergone any changes in the past? If yes, when and why?
   

2. 
   Does your country have a functional HIV and/or AIDS case surveillance system? Specify which system exists.
   

3. 
   If your country is not conducting HIV and/or AIDS case surveillance, discuss why.
   

4. 
   If your country does have an HIV or AIDS case surveillance system:
   

b. How have the data from the system been used?

5. 
   Is HIV case surveillance conducted in your country?
   

6. 
   Describe existing challenges in your country that affect efficient HIV case surveillance. What are some possible solutions for these challenges?
   

Work on this case study independently.

1. 
   You are the national 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 CAREC epidemiologist is conducting country visits to discuss ways of improving surveillance. During your meeting with the CAREC epidemiologist, you are asked to suggest additional surveillance activities in your country that you believe could be implemented and successful. Describe what these activities would be.
   

2. 
   The CAREC epidemiologist has indicated that there is interest in using data collected from HIV and other care programmes for HIV case surveillance. What programmes would you suggest using?
   

unit is about

This unit provides an overview of the history and purpose of clinical staging and surveillance case definitions for HIV infection. It includes:

• 
  a brief history of the clinical staging system and surveillance case definitions for HIV infection
  
• 
  a description of the recent (2006) WHO HIV clinical staging criteria and criteria the presumptive and definitive diagnoses
  
• 
  a description of the recent (2006) WHO surveillance case definitions
  
• 
  an explanation of the link between HIV clinical staging, antiretroviral treatment recommendations, and HIV case surveillance
  

Warm-up

1. 
   True or false? In the revised (2006) adult and paediatric WHO HIV clinical staging systems, there are four clinical stages.
   

True False

2. 
   True or false? The revised (2006) WHO advanced HIV infection case definition includes the same clinical stages for adults and infants.
   

True False

3. 
   List the three options for HIV case surveillance that are recommended in the revised (2006) WHO guidelines.
   

8. 
   True or false? The clinical criteria included in the revised (2006) WHO advanced HIV infection surveillance case definition only include definitive diagnosis of clinical events.
   

True False

Warm-up questions, continued

8. 
   List four reasons why HIV clinical staging systems were developed.
   

8. 
   True or false? Previous surveillance case definitions in developing countries focused only on stage 4 (AIDS).
   

True False