The latest report suggesting that there has been a possible slowdown of the HIV-epidemic in South Africa should be regarded as an act of providence, rather than something for which the department of health can claim credit.
The antenatal HIV survey for 2007 showed a possible fall in the percentage of HIV among pregnant women attending public sector antenatal facilities.
But the figures have introduced a fresh controversy: the absolute figures do not add up. This anomaly is not easily ascertainable, however, from the graphs in the health department’s document.
The problem is that the assumptions made by the analysts to create a coherent picture are not recorded, thus clearing the way for the charge that the data have been manipulated to give the impression of victory in the war against HIV.
The department of health has said it will prove the veracity of its document. Assuming that the figures are genuine, is the graph really an indication that the tide of the HIV pandemic is turning? The answer is ”yes”.
It would be startling if the figures had dropped in 2006 and again in 2007. If there has been a decrease what would have brought it about?
Suggestions that it is a triumph for national safe-sex campaigns can be discounted immediately — nowhere else in the health service is there any evidence of sex being practised more safely: the incidence of other sexually transmitted diseases, including syphilis, is inching up; even HIV patients on antiretrovirals do not appear to be using condoms more frequently and, anecdotally, sexually active teenagers report that they use condoms only occasionally. Besides, in addition to the lack of results, the campaigns themselves are visibly a hotch potch of confusing messages.
There are three possible explanations for the dip in the graph:
- The natural progression of the epidemic: all known infectious diseases have shown a similar pattern — a period of rapid escalation of new cases, a plateau period and a state of decline. For some time doomsday scenarios claimed that because of the sexual nature of infection, HIV might prove to be the exception to this trend and the South African epidemic might never decline. Yet evidence from other countries (most prominently Uganda, Brazil and Thailand) seemed to bear out the typical epidemic pattern. Naturally the rapid escalation and plateau phases are country specific — one cannot predict when the graph will dip.
- The influence of cumulative death rates: HIV deaths nationally are difficult to assess, but probably range between 300 000 and 500 000 a year. In removing large numbers of HIV-infected mothers from the potentially pregnant population death alone might explain the falling numbers.
- The effect of ARV therapy on a population: the infectiousness of HIV in a population is related to the amount of virus in the blood of the infected individuals, called the viral load. Thus, it would make sense that the more people receiving treatment the less infection is likely to be transmitted.
The likely reason for the apparent decline in levels of HIV infection is a combination of these factors.
What will be more interesting as the years pass by is whether this decrease will be maintained and how, as increasing numbers of people take antiretrovirals, opposing trends play out. On the one hand the death rate will fall and the number of people living well on ARVs, and hence falling pregnant, will increase; on the other, infectiousness is expected to diminish as the national viral load comes down.
What is certain is that the health department should not be quick to claim credit for the apparent slowdown in the HIV epidemic since only the ARV treatment programme can be attributed to public policy. A treatable infectious disease, the incidence of which declines because of accumulated death rates, should be a matter of national shame.
Anonymous HIV testing
Encouraged by the World Health Organisation, almost all countries with a significant HIV-epidemic now carry out some variant of anonymous testing for HIV. South Africa uses blood from routine tests on pregnant women.
The standard of care for pregnant mothers includes a blood test for syphilis, a common, yet easily treatable sexually transmitted disease that can cause severe illness or even death in newborn babies.
A speck of blood is taken from the sample of bloods taken routinely for syphilis at public antenatal clinics and is tested for HIV.
If the result is positive, no further action is taken because the test is an anonymous blood.
Critics argue, largely correctly, that one cannot extrapolate these figures to assess the number of people in the country who have HIV.
Since pregnant women, by definition, have had unprotected sex at least once it can be argued that they represent a minority of women who do not use condoms and therefore the study might over-represent the level of HIV in the population.
Conversely, because HIV reduces fertility, it can be argued that monitoring HIV-positive pregnant women will result in underestimation of the epidemic because it will under-represent the more fertile HIV-negative population.
Nevertheless, the trends reported by the health department’s surveys seems incontestable — for example, when figures showed some years ago that there were districts in rural KwaZulu-Natal where a pregnant young woman’s chance of having HIV was more than 50% this was borne out by many anecdotal reports of the HIV infection exploding in selected rural areas.
Elvis Jack is a doctor who specialises in HIV/Aids