Friday, May 19, 2006

Microbe wars

With the discovery of penicillin, the first antibiotic, by the 1950’s many medical practitioners were arrogantly proclaiming that we could close the book on all infectious diseases. Why these fools failed to factor in evolution before making such statements is not entirely clear, but the fact remains: bacteria evolve millions of times faster than more complex organisms like humans. That’s the price we pay for our lengthy and oh-so-productive and meaningful lives. Anyway, disease causing bacteria of course found a way to tolerate penicillin. Not only that, but our over-reliance on antibiotics and the fact that we’ve been unable to find a new form of antibiotic since the 1960’s, has put these microbes into evolutionary-hyperdrive. The result, superbugs…organisms resistant to every antibiotic in our arsenal. Penicillin, methicillin, vancomycin…all useless in terms of benefits, but they will however devastate your gut’s beneficial microfauna (pro-biotics), causing additional unpleasant side effects.

In an attempt to find new treatments for bacterial diseases, scientists are once again turning to phages, viruses that infect and kill bacteria. It’s an idea that pre-dates antibiotics, but due to a lack of understanding at the time, took a back seat to penicillin and was virtually abandoned. Just like a dormant virus patiently waiting for an opportunity to strike, so waited the idea of using phages for treatment of infectious diseases. With antibiotics failing at increasing rates, phage treatments are the new focus. Modern technology now allows us to better understand how phages work and which types would be most effective against which bacteria. Methods for extracting purer samples and doses of phages are also now available. Antibiotics it seems have a new rival in their quest to heal mankind…the mighty phage.

Not so fast. Just as phage treatments looked as though they were finally gaining the upper hand, a new antibiotic is discovered. While screening a sample of dirt from South Africa, scientists discovered a compound that when tested in mice, destroyed antibiotic resistant superbugs like enterococcus and staphylococcus aureus, rampant in hospital settings around the world. Unlike traditional antibiotics which attack a bacterium’s metabolism, the new antibiotic blocks enzymes needed to make fatty acids, the building blocks of cells. The compound is non-toxic, and as such shows real promise in the development of a new wave of antibiotics.

So, this all brings me to the bird flu virus (H5N5), or as the media seems to refer to it as…our apocalypse! Its coming they say. It’ll soon be transmittable from person to person, with ease. We’re all doomed!

I doubt it, and why I doubt it is mentioned above. No, I don’t think that new phage treatments will lead to a cure for bird flu, nor will the newly discovered antibiotic do us much good in this case. How could they? A phage is a virus that infects bacteria…it wouldn’t infect and destroy another virus like H5N5 (although some theorize that even viruses can be infected by viruses). Similarly, as successful as new antibiotics are at treating diseases caused by bacteria, they do not cure viral infections. The key to the answer actually lays in the first paragraph…evolution. Nothing, not even viruses are exempt from this evolutionary struggle of constant change (mutation) and sacrifice in order to gain an edge and exist for another day. In order for a virus (or any micro organism) like H5N5 to become more dangerous to humans, it would have to evolve…significantly changing from its current state. In order to infect more human hosts by either becoming airborne or jumping species more easily (or any number of other ways) the virus would almost certainly have to trade in some or all of its virility. In this scenario, yes, more of us would get infected, but fewer would get sick and die, and many may even show no ill effects at all.

Also, for a virus to be truly devastating to entire human populations, it would need the ability to keep human hosts healthy enough to be mobile at the very time when they are most infectious, thus maximizing exposure to new hosts. This would be when the lungs and other key organs are completely overrun by the virus. With the current H5N5 virus most human hosts are immobile and show severe signs of sickness by the time they reach their optimal infectious state. The only contact they have at that point with other potential human hosts is in hospitals with doctors and nurses, who hopefully are taking the necessary precautions in dealing with them. So, in order to gain this ability the virus has to trade-in some of its virility. Either way there are going to be tradeoffs and we must not forget that it isn’t in the virus’ best interest to kill us all off either.

How confident am I that the threat of bird flu is over exaggerated? Well, I’m not quite ready to have a chicken sneeze in my face just yet, but I’ll donate a peppershaker to the cause. Any takers? Seriously, I’m not the only one saying this. There are actual intelligent and educated people out there who share this view and have evidence to support it, but if I am wrong, may we all be stricken down by some micro-army from birdland, somehow!