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| Questions linger on the dramatic fall of HIV prevalence |
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| Written by Arthur Okwemba | |
             HIV/AIDS experts who talked to the Horizon said Aids prevalence indicator should not be used as it provides misleading indications once the prevalence falls below 10 per cent. Instead, they want the country to undertake incidence studies that show the rate of new infections and how the disease is behaving in different populations. “Falling Aids prevalence rates are not a statistics to be happy about as they only show people are either dying or have migrated to other places,” says Dr Patrick Orege, former Director of the National Aids Control Council (NACC). “One of the problem I have had with prevalence even when at NACC was it did not provide enough information, and I shared this with my colleagues.” Dr Orege says where the prevalence level has reached needs accurate incidence figures within key population stratas to guide the designing of interventions. In the Kenyan case, other HIV/AIDS pundits believe people are either dying or migrating to other areas or countries. Even in Uganda, one of the celebrated stories, scientists later discovered death was responsible for the falling HIV rates and not success of interventions. During the 2005 Twelfth Annual Retrovirus Conference in Boston, a study on Uganda indicated that it was “primarily mortality and not behaviour change that was responsible for 80 per cent of the reduced prevalence in one Ugandan district.” In Kenya, with free access to ARVs, the dying aspect contradicts the normally accepted explaination of the drugs lengthening the lives of those living with the virus. Ordinarily, as more people are put on ARVs, they are supposed to stay longer and not die. The results being the Aids prevalence rate reducing at a very slow rate or stabilizing than what the Kenyan statistics show. Could it be the assumptions or the formula or high quality HIV kits being used behind the current statistics? Or are this success stories donor or politically driven? There are suspicions that use of various assumptions and HIV testing kits may be behind the dramatic reduction in HIV prevalence. The sensitivity and specificity of a given HIV testing kit determines the number of false or true positives and negatives a kit will give. Hence if the kit gives false negatives, then the prevalence rate are usually lower. In 2000, for instance, HIV prevalence rate was put at 14 per cent. But in 2001 when a different HIV test kit with enhanced sensitivity and specificity qualities was used, the prevalence rate fell to about 10 per cent. Again, NACC’s current Director, Prof Alloys Orago argues the formula and process of coming up with HIV prevalence is based on the one approved by the UNAids and which is being used in many countries. He further say the reduction in HIV prevalence rate from 5.9 per cent in 2005 to 5.1 per cent now was subjected to rigorous appraisal by the monitoring and evaluation sub-committee whose membership includes UNAids, Centre of Disease Control, National Aids Control and STDs Programme (Nascop). This means any interpretation or extrapolation made using this statistics gives a near true picture of the HIV scenario in the country. Yet, estimation of a country’s prevalence, especially based on data collected from the sentinel surveillance in antenatal clinics, has been under scrutiny in recent past. There are fears such estimation may not present the true picture of what is happening. Indeed in 2003, HIV prevalence stood at 10 per cent based on surveillance done in antenatal clinics. But when the national Demographic and Health survey was done in the same year, the prevalence was about 7 per cent. It then seemed the survey was a better way to estimate prevalence than using data from antenatal clinics. Now a number of scientists think the country might be sitting on a powder keg by not carrying out incidence studies, which accurately shows the number of new infections and the specific populations they are taking place in. They argue that such an indicator would the best way to measure how the country is performing against the disease. Incidence studies show the number of new infections, the populations affected, and the interventions needed to effectively tackle the disease. They are respected by the scientific community as one of the key strategies in tackling a disease like HIV/Aids. According to Prof Orago, an epidemiologist himself, the country knows the HIV incidence or number of new infections each year. But this incidence is estimated through extrapolation using prevalence data gathered from annual sentinel surveillance in antenatal clinics. “The method we are using is approved by UNAids and is widely used in South Africa and Uganda. In fact in Africa, we are one those doing well in monitoring the disease this way,” says Prof Orago. This is where other scientists defer with NACC. They argue that once the prevalence falls below 10 per cent, then it is not a better indicator for extrapolating the incidence. Also, this extrapolation is done for the general population, hence difficult to know infection rates among vulnerable groups such as the youths, women, and commercial sex workers. “Without knowing the rate of new infections in these and other groups, it maybe difficult to pinpoint the drivers of the disease,” says an official of the Ministry of Health, who requested anonymity. Information released about three weeks ago shows incidence or the number of new infections to be on a downward trend. From 85,000 cases in 2004 to 60,000 in 2005 and 55, 000 in 2006. To get this data using the incidence model for extrapolation, scientists use the national HIV prevalence rates and behavioral data. High risk groups, the presence of HIV in a particular group, the prevalence of sexually transmitted infections, the average number of partners per year, use of condoms during sexual intercourse, and number of needles shared by drug users, are some of the behavioural data applied when extrapolating HIV incidence. For Kenya, such comprehensive information is captured in the 2003 Kenya Demographic and Health survey. NACC admits they are using this information to extrapolate incidence rate in the country. The only problem is the statistics being used were collected more than five years ago. During the intervening period, many things have happened, especially shifts in behaviour patterns. Increasing number of women, for example, are using morning after pills, implying they are having unprotected sex and exposing themselves to HIV infection. The number of men having sex with men is on the increase as well, evidenced with what is happening in schools. Using statistics of five years ago may therefore not give a true picture of the scenario now. In addition to this, the incidence data generated is based on the HIV prevalence in the general population. Yet in most cases, incidence information within specific groups rather than the general population helps to focus on the drivers of the epidemic, and the appropriate interventions required. Although prevalence rates is seen as the cheapest way for African countries to monitor how they are fighting the disease, knowing the rate of new infections among groups like youths, commercial sex workers, men having sex with men and Intravenous Drug Users, is critical. “As we operate now, we do not know with certainty which sections of the population are fuelling the spread of the epidemic,” says Dr Orege. In Uganda, celebratory mood around falling prevalence rates turned into tears after the numbers of those infected started spiraling up again. There is one school of scientists who claim that incidence studies among specific populations were not done; hence the country did not grasp well the drivers of the infections. Meanwhile, the population celebrated the success and complacence set in. Some of the NACC employees admit generating incidence information is a challenge, and are now conducting a National Kenya Aids Indicator Survey, to determine with some certainty, among other things, the Aids prevalence and incidence. Results of this four month household survey are expected before the end of this year. In the process too are plans by the government to procure an HIV testing kit from Italy that is able to provide incidence information. The only challenge is, some of such Kits designed in America have been giving problems to laboratories locally. The main reason being these kits are designed to be sensitive to HIV strains circulating in the country of manufacturer and may not work well when blood samples of other strains is used. Prof Omu Anzala, a virologists and Kenya Aids Vaccine Initiative (KAVI) Programme Director, says the government can either use laboratory techniques or studies to determine the rate of new infections within various sections of the population. Laboratory tests such as the P24 antigen assays can help to show a new infection. Longitudinal studies- a prerequisite in knowing incidence level with a measure of certainty- are said to be the ones NACC and National Aids and STDs Control Programme, need to concentrate on. In such studies, for instance, 100 HIV negative within a specific age group are followed for about one year. At the end of this period, the researchers are able to tell how many have been infected, hence determining the incidence levels. An AWC-Feature |
| Kenya Audio Visual Archives Conference |
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The African Woman and Child Feature Service, the Kenya Archival Study Group and the Ford Foundation office in Nairobi, Kenya will hold the Preservation, Conservation and Restoration of Audio Visual Media Conference. The conference will be held at the National Museums of Kenya in Nairobi, from December 3rd – 5th 2008. |
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