I think the quote at the end of this piece is probably accurate. It undercuts the rest by saying that fears of a new, aggressive strain of HIV are “a storm in a teacup” [© Benjamin Mackie 2004]. But ten years ago I was sitting in a common room when one of the most senior professors of medicine in the UK predicted that such a thing would happen. I thought he was wrong, for what that’s worth (and his specialty isn’t infectious disease).
14Feb05 — 4
Looking at the article, it refers to a patient “who reported multiple sex partners and unprotected anal intercourse, often under the influence the amphetamine crystal meth”, then goes on to say “He had reported tested negative in May 2003”, but there doesn’t seem to be a view that he might actually not have been negative at that time either due to testing failure or he was lying, both could be attributed to substance abuse.
Bottom line is that communicability is something like 98%+ tied to your own behavior, so if you feel like you didn’t have anything to worry about before, then you still don’t have much to worry about today. The only thing that need to be hurried is education, but that was also no differnt before this discovery. Getting sub-saharan Africa to stop believing in witch-doctor virgin-cures might be a good start.
As an evolutionary arms race between an organism and our attempts to kill it is not exactly a novel idea (and hasn’t been since penicillin resistance was first noted), can you explain a little more about what exactly the professor predicted and why you thought he was wrong. Thanks.
The prof in question argued that HIV was such a fast-changing virus—it copies itself very inaccurately so mutates rapidly—that a more aggressive form ought to emerge very soon. This version would infect more cell types in the human body (normally HIV can only enter and successfully co-opt a subset of cells in the human immune system) and be transmitted more easily. He believed that such a strain would inevitably “out-compete” more benign variants. In any given meeting between a carrier and an uninfected individual the nastier mutant would be more likely to hop onto its new human host.
This argument is superficially plausible, but evolutionary theory doesn’t allow you to make predictions like this with any real confidence, because there are so many subtle and interdependent factors determining the success of a particular pathogen “lifestyle”. HIV does indeed change rapidly and this is indeed one important reason why single-drug treatments have limited usefulness in controlling the spread of the virus even within an individual, but high mutation rates cost HIV heavily. There are all sorts of other reasons why it might be impossible for HIV to successfully adopt a more aggressive “strategy” that have nothing to do with mutation rates. You could make the opposite argument in fact: HIV hangs around in so many individuals for so long mutating all the time; why hasn’t a more vicious form emerged already? I’m not saying that such a strain will never appear, but I am saying there isn’t a solid scientific case for it happening. If I had a hundred pounds to bet I wouldn’t put it on his being right any time soon.
On the other hand, for a long time, many biologists believed that there was such a thing as a “well adjusted parasite”, and that, with time, most disease-causing agents (pathogens) would tend to reach a grumbling truce with their hosts because it was in their interests to do so. They would get to infect more individuals more reliably and thereby spread their genetic material more widely not by bringing their victims down low, but by treating them well so they could hitch a ride on the next passing carrier. There certainly are some pathogens that behave like this. For example, once you’ve been infected with the viruses causing glandular fever (mononucleosis), chicken pox, or cold sores, you find that they settle into your physiological home for life, like mad old bints in the loft. In return for a peppercorn rent they usually keep themselves to themselves, muttering gibberish. But every once in a while they burst out to beat you over the head with a metaphorical broom. More recently the view that all parasites should aspire to such a compromise with their hosts has been, I believe, successfully attacked. Despite this, I’d definitely put a hundred quid on HIV having that kind of evolutionary dotage—it’s some of the way there already.