AIDS staistics in Africa?

Question

Is there a website that explains in detail how AIDS stats in Africa are obtained? How do they come up with figures like 30% are infected?

Answer 1

This article might be of assistance

India's HIV prevalence rates have been grossly overestimated and require substantial downwards revision, according to a late-breaker presentation at the Sixteenth International Conference in Toronto on Thursday August 17th. Population-based HIV prevalence estimates in Andhra Pradesh, the south Indian state thought to have the highest prevalence of HIV, were found to be two-and-half times lower than estimates based on sentinel screening at antenatal and sexual health clinics.

At the end of 2005, India's National AIDS Control Organisation (NACO) estimated that there were 5.21 million people living with HIV, although this figure had been criticised by some as an underestimate.

Indeed, UNAIDS estimated that the number of people living with HIV in India at the end of 2005 was closer to 5.7 million - higher than South Africa's estimated 5.5 million - although it suggested a lower and upper range of 3.4 million and 9.4 million, respectively.
******************************************************************************************************************************
NACO extrapolates data from the public health system – primarily women testing for HIV during antenatal care, as well as anonymous surveillance from sexual health clinics – in order to estimate HIV prevalence in India, and until now no population-based study had systematically examined the validity of this extrapolation.

******************************************************************************************************************

Investigators from the Administrative Staff College of India and the Institute of Medical Sciences in Hyderabad sampled 13,838 adults aged 15-49 from 66 rural and urban clusters that represented the 4.5 million adults in the Guntur district of south India's Andhra Pradesh state, which is thought to have the highest HIV prevalence in India.

Demographic data were obtained from a total of 12,617 individuals (91.2% of those sampled), and dried blood spots obtained at the same time were tested for HIV antibodies, p24 antigen and HIV RNA. The results were then compared with the HIV estimates from NACO's sentinel surveillance data.

The investigators found that the adjusted HIV rate in adults was 1.72% (95% CI, 1.35-2.09%), with a slightly higher prevalence in men (1.74%; 95% CI, 1.27-2.21%) than women (1.70%; 95% CI, 1.36-2.04%). Prevalence was higher in urban settings (1.89%; 955 CI, 1.39-2.39%) compared with rural settings (1.64%, 95% CI, 1.10-2.18%).

Using a standard of living index (SLI), the investigators found that HIV prevalence rates were twice as high in people who were in the lower half of the SLI (i.e. poorer), compared with those in the upper half (2.58% vs 1.20%, respectively).

Around 23% of pregnant pregnant women had accessed antenatal care through the public health system in the previous two years. Significantly, they discovered that very poor women were over-represented, which resulted in an unusually high HIV prevalence rate (3.61% versus 1.08% of pregnant women who did not use the public health system). This would have skewed the surveillance-based data which found antenatal clinic HIV prevalence to be 3%.

The investigators calculated that their population-based estimate for the Guntur district is 45,925 adults after adjusting for underrepresented high-risk groups. In contrast, NACO's surveillance-based estimate was 112,635 adults. In other words, population-based HIV prevalence was two-and-a-half times lower than the sentinel surveillance data.

By applying the investigator's population-based estimates to the entire state of Andhra Pradesh, this results in a reduction from 1.44 million adults living with HIV to just over half a million.

Lalit Dandona, of the Centre for Human Development in Hyderabad, presenting, concluded that NACO's method for estimating HIV prevalence grossly overestimates HIV in all south Indian states – home to around three-quarters of India' HIV-positive population – and which have a similar pattern of public health system use by the poorest people. Therefore, NACO's current HIV estimate of 5.21 million for India should be revised downwards by a substantial amount.

Reference
Dandona L et al. A population-based study suggests that the HIV estimate for India needs major revision. Sixteenth International AIDS Conference, Toronto, abstract ThLB0107, 2006.

Answer 2

NDIAN REDUCTION IN HIV FIGURES NO MIRACLE NEW DELHI (AP) - India, home to the second largest number of people infected with the HIV virus, dropped a bombshell last week when it declared that new cases fell by 95 percent in just a year.

http://www.outinamerica.com/Home/News.asp?articleId=8807

It is very well documented that when researchers switch from an ANC (Ante-Natal Clinic) survey, to a DHS (Demographic and Health Survey), that 'infection rates', or rather the number of people 'testing positive' drops dramatically.

For instance, see the article below. The boneheaded stupidity wants to make you puke. They use a different survey type, get much lower infection rates, and then explain it as 'suggesting a turning point in the battle against HIV/AIDS in a country with the world's highest HIV infection rates'. But those 'world's highest infection rates' were based on the old survey type... Oh never mind.

You might think that second year university students get their brains drilled out or something.

And just to add, the fact that 'six percent of girls' in Swaziland test positive says nothing about whether they are actually HIV positive - it just means that they test positive on these tests, which are always ELISA. If they used Western Blot for confirmation, even less would test positive.

***********************************************************
UNICEF DHS IN SWAZILAND

MBABANE, 27 August (PLUSNEWS) - A dramatically lower number of Swazi teenage girls are being infected by HIV than was previously estimated, suggesting a turning point in the battle against HIV/AIDS in a country with the world's highest HIV infection rates.

The findings in the report, 'A Baseline Study on HIV Risk Factors', commissioned by the UN Childrens' Fund (UNICEF) are derived from interviews and blood tests of over 1,000 Swazis in two rural areas and revealed that only six percent of girls aged from 15 to 19 were found to be HIV-positive, with most of the HIV infections occurring among older girls.

"This is the first time we have had data from a scientifically accurate survey of randomly selected households. It confirms some trends we had suspected, but which were belied by previous HIV estimates," said Dr Alan Brody, country representative for UNICEF.

"This is different from anything that has been seen before. The conventional wisdom is that many more girls were infected," he told PlusNews.

The study was prompted by the results of the government's 2002 sero-surveillance study, which estimated that 32.5 percent of teenage girls between the ages of 15 and 19 were HIV-positive.

http://www.plusnews.org/AIDSReport.ASP?ReportID=3819&SelectRegion=Southern_Africa&SelectCountry=SWAZILAND



Note that the survey was with teenage girls. Swaziland is a very poor country. Medical care is triaged. These girls are pregnant so they get more care. Note well that being pregnant can cause false positives to the hiv antibody test.

Note that in the Swaziland case, the national estimate of HIV infection dropped 81.5% overnight (it went from 32.5% to 6%). This is a result of changing survey methods - pregnant women to broader spectrum surveys.

In surveys, even the DHS type, only ELISA is used. I think sometimes twice, for 'confirmation'. Western Blot is NEVER used for confirming positive ELISAs in surveys.

The HIV antibody tests do not detect a virus. They test for any antibodies that react with an assortment of proteins experts assure us are unique to HIV which, almost everyone agrees, is a retrovirus and the cause of AIDS. What happens is this: A sample of blood serum is incubated with a mixture of these proteins in a test called an ELISA, an acronym for Enzyme Linked Immunosorbent Assay. The ELISA is positive if the solution changes colour thereby indicating a reaction between the proteins in the test kit and the patient's antibodies. However, according to many experts, the ELISA is not specific meaning it may react in the absence of HIV infection. In response to this, testing authorities have developed strategies such as repeat testing of all positive ELISAs and following up those twice positive with a third but different antibody test known as the Western blot. In the Western blot the "HIV" proteins, about ten of them, are located at discrete spots in a paper strip, rather like the one your doctor uses to perform multiple tests on your urine. Serum is added and wherever there is a reaction a colour change occurs which shows up as a dark band. The test is read by noting which bands show up, in other words, which proteins react. Certain combinations of bands are defined as a positive test. It is enigmatic that the location and number of bands required for a positive Western blot varies around the world. They may even vary between laboratories within the same city. In Australia four bands are required, in Canada and much of the United States, three bands suffice. And in Africa two will do. In the US Multicenter AIDS Cohort prospective study involving several thousand gay men, one "strong" band was deemed sufficient. If each of the above indicates HIV infection then HIV must cause different populations of antibodies to appear in different places. I don't know about you but to me that sounds very odd. But at least it gives some Africans a way out. All an African has to do is have a test in Australia because two bands would not be considered positive here. Nevertheless, in spite of lack of standardisation and other problems such as reproducibility, the Western blot is accepted to be in excess of 99.9% specific and if positive is regarded synonymous with HIV infection. In some countries similar claims are now made for the HIV ELISA without recourse to the Western blot.

Officially, it is too expensive (although no one mentions the cost of bad social policy decisions based on corrupted data).

The big difference between ANCs and DHS's, is that ANC surveys are based only on pregnant women at antenatal clinics. The girls in the DHS survey, are ordinary teenaged girls.

And pregnant women will test positive at the drop of a hat, on a host of tests. Maybe there is something about having 2 immune systems, or the hormones that are released, or just their higher sexual activity, that creates the conditions for false positive tests.

What is unconsciounable, is that the results from pregnant women are directly extrapolated to all women, and to men and children as well.

That is where you get '32% of Swazis are HIV positive" nonsense.

Bad tests, translated into terrible sociology and statistics.