Hitchhikers learn more about SA pandemics

26 May 2002
IN HIS presentation to the Vice-Chancellor's Open Planning Forum, Professor Lafras Steyn gave the assembly a few scientific and social insights into HIV/AIDS and other diseases in his talk, A hitchhiker's guide to HIV/AIDS.

Steyn, Head of the Department of Clinical Laboratory Sciences and the Division of Medical Microbiology, explained that three of the five human pathogenic microorganisms able to cause worldwide outbreak of infection are active in South Africa. These are the Human Immunodeficiency Virus (HIV), Mycobacterium tuberculosis, and Vibrio cholerae.

According to Steyn, the provenance for many diseases can be traced back to the development of agriculture, and the associated interaction between humans and animals. As a result, animal pathogens were increasingly transferred to humans, he explained.

Over the last quarter-century, at least 25 new pathogenic agents have been identified, he added. This he again ascribed to the greater interaction between humans and – mostly, domesticated – animals.

Despite conspiracy theories that suggest that the developed world engineered the pernicious virus to undermine the developing world, there is compelling evidence that HIV-I came from the chimpanzee population instead, Steyn said.

"If you had designed or thought up a virus, you couldn't have come up with a better pathogen," he commented on the HIV organism.

Comparing the impact of viruses and bacteria, however, Steyn noted that one of the latter, Mycobacterium tuberculosis – his personal favourite – is still the most important bacterium in the world.

One-third of the world's population is – latently – infected, although many of those infected will never suffer from the disease.

Drawing smallpox into his equation, Steyn noted that, unlike HIV and TB, this is the only disease of the three to provide immunity after infection. "This is one of the reasons we have great difficulty making vaccines for TB and HIV, and why we could eradicate smallpox."

Steyn also challenged perceptions that women are to blame for the spread of HIV, misconceptions derived from the high infection rate of young women (30%). Statistical evidence would suggest, however, that older men (aged 30 to 34) have an important role to play in the transfer of the virus, he said.

"The implication is that most probably there is much interaction of HIV-positive older men with young women."

On a cautionary note, Steyn added that HIV and AIDS has changed ideas around life expectancy in South Africa. He also noted that the provision of anti-retrovirals is essential to prolong the working life of young HIV-positive adults.

The social problems that arise should this not be done – such as generations of orphaned "feral" children – are immense, he said. "HIV is the most important thing the country has to deal with in the foreseeable future.

"Leadership in this regard must come from places such as the University of Cape Town."

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