Monday, March 9, 2009

The end of AIDS?

Today we talked about vaccines. Although a vaccine allows us to establish herd immunity to eliminate a disease this is not our only mechanism for disease eradication. If a disease does not have an animal reservoir and only infects humans then we could, theoretically, eradicate it by preventing all transmission. We can do this by altering human behavior (see for example Guinea Worm) or by treating patients so they are no longer infectious.

Efforts to control the spread of AIDS have generally focused on altering human behavior to reduce transmission (eg practicing safe sex, providing clean needles etc). This has had success in some communities and at some times but has never been sufficient to even consider talk of elimination or eradication.

However the latest anti-retroviral drugs are so effective at reducing viral load that those patients on them are effectively no longer contagious. So if everyone with HIV were on therapy, there would be little or no transmission. This raises the fascinating possibility that with a concerted effort we could turn the tide and talk about eliminating, or at least controlling AIDS. For further discussion see the article Are we about to eliminate AIDS? in New Scientist magazine a few weeks ago. Just a couple of excerpts:

It's a simple idea, but the obstacles to implementing it worldwide are enormous. Persuading everyone with HIV to start therapy purely for public health reasons could be ethically dubious. To identify everyone who is HIV positive would require such widespread testing that some may feel it breached their civil liberties. Then there is the question of who would fund such a massive undertaking.
In 1985, when HIV testing began, no treatment for the virus existed, so a positive result was effectively a death sentence. Fear of the virus and the fact that it spread most easily among gay men and intravenous drug users meant people with HIV were shunned, as well as being barred from taking out health and life insurance. The decision to have the test was generally an agonising one and many decided it was better not to know.
What is certain is that, however and wherever it is attempted, such a scheme will be controversial. Hard-line religious groups that view AIDS as divine retribution are unlikely to help out. Some liberals, on the other hand, might resist the idea of mass testing. "Should we try a social intervention which infringes on people's civil liberties?" asks Conant. "AIDS infringes upon people too. If we're going to stop this epidemic, this is a responsibility that society has to shoulder."

and from the accompanying editorial:

Bankrolling such a long-term programme would cost serious money - initially around $3.5 billion a year in South Africa alone, rising to $85 billion in total. Huge as it sounds, however, it is peanuts compared with the estimated $1.9 trillion cost of the Iraq war, or the $700 billion spent in one go propping up the US banking sector. It also looks small beer compared with the costs of carrying on as usual, which the WHO says can only lead to spiralling cases and costs.

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