The analysis of the quality of surveillance systems for HIV continues to reflect wide variations in monitoring the epidemic, within and across regions. Fewer countries in this round of assessment have been categorised as fully functioning (40 vs 48) and fewer have been categorised as poorly functioning (44 vs 57) compared to the previous round of assessment in 2004.2
Over 68% of the global number of HIV infections are in sub-Saharan Africa,19
and in those countries with the highest HIV prevalence, the surveillance systems are generally good. As such, estimates of HIV prevalence and its impact in those countries, particularly in countries that have also conducted national population-based HIV surveys, are generally robust and of good quality. With better surveillance data, HIV estimations in these countries have improved over time and are continually adjusted as data and assumptions are updated,10
providing a more robust picture of the global burden of disease. Indeed, the quality of surveillance in many countries in this region has improved owing to expanded sentinel surveillance systems as well as the availability of information from national population-based surveys in which HIV testing has been included.
Surveillance systems judged to be of higher quality are also found in South and South East Asia. As in sub-Saharan Africa, the epidemics in some countries in this region are older and more mature than in other regions and surveillance systems in the majority of these countries are well functioning. Only about a third of the surveillance systems in Latin America and the Caribbean have sufficient information to be a fully functioning surveillance system. In the rest of the countries considered in North Africa and the Middle East, and in Eastern Europe and Central Africa, surveillance systems are either partially functioning or not functioning well at all. The exception in Eastern Europe was the Ukraine with a well functioning surveillance system, particularly among IDU.
The results of this analysis reveal general overall weaknesses in most (68%) of the evaluated countries’ surveillance systems. The number of countries with low-level or concentrated epidemics with studies considering MSM is limited almost exclusively to countries in Latin America and South Asia. This is also true for CSW. This may represent the true nature of the disease burden, the focus of prevention interventions or may represent populations more easily accessible and accepted by the local culture. In countries in Central and Eastern Europe, the preponderance of information about the epidemic comes from studies focusing on IDU.
Additionally, even in those countries where data exist for the populations most at risk of infection, consistent data collection over time does not, and trends in the epidemic are difficult if not impossible to monitor. Though the methodology used in this assessment attempted to address representativeness and coverage of surveillance, the actual size of high-risk populations remains difficult to quantify. Most HIV prevalence data in these high-risk populations are found in specific studies with limited sample size and limited sampling frames. Accurate extrapolation of the results of these studies to the specific high-risk population would require an estimate of the population size. The value of data from studies such as these would be enhanced by estimations of the size of the high-risk populations. Further, just as correction factors have been suggested for prevalence estimates based on ANC data using data from population-based surveys, studies are needed to determine if such adjustments are needed for estimations among high-risk populations (that is, Workbook or EPP).21 22
The analysis presented here has several limitations that must be considered. First, there is the possibility that some data in countries have not been considered in this analysis. Every effort has been made to ensure that available data have been identified by contacting national epidemiologists from each country and requesting the most recent data available. The scope of the data considered appropriate for the analysis in low-level or concentrated epidemics was limited to data on high-risk populations, and for the analysis in generalised epidemics was focused on antenatal clinic surveillance and population-based surveys that include HIV testing. If a country uses data from other sources for monitoring the epidemic, such as data related to blood screening, those data were not captured here. Additionally, publications were considered in English, French, Spanish and Russian. Other languages were not considered.
Surveillance of infections such as HIV is of course problematic because of the asymptomatic nature of the infection for most of the duration of the infection. For many individuals in countries with low-level and concentrated epidemics, barriers to testing (such as access and stigma) make it difficult to adequately assess the true burden of infection in certain populations.23
However, with the increase in the availability of treatment, an increase in the number of people undergoing counselling and testing and an increase in the number of identified cases might be expected.
This paper considered the most recent data available for the last seven years in assessing the quality of surveillance systems for monitoring the HIV epidemic. In countries with the largest disease burden, surveillance has continued to improve over time, and the addition of large population-based HIV prevalence surveys in these countries has greatly enhanced the reliability of the data. In many other countries, specifically those with low-level and concentrated epidemics, the quality of data has also improved, though many countries still lack the consistency required to follow trends over time in these high-risk populations. There are gaps in some countries’ data on high-risk populations, and behavioural data are generally scarce. Estimating the size of high-risk populations and the frequency of exposure to HIV remains a difficult task.
- The quality of HIV surveillance seems to be improving.
- However, some countries still lack the necessary data to accurately assess the course of the epidemic. Trend analyses will be difficult.
- Many countries with low-level and concentrated epidemics could improve their surveillance by collecting data from all groups at risk for infection.