Monday, June 20, 2011

Pathogens 101

There's been a lot in the news recently about deadly infections around the world. First there was the H1N1 swine flu that threatened to turn into a pandemic: luckily it turned out to be a very mild flu-like illness, and not the long awaited "big one" predicted in the media. More recently there has been the E Coli outbreak in Germany that has killed several people and left hundreds needing dialysis for kidney failure. So what do we know about these germs - or pathogens as the experts call them?

Firstly, viruses and bacteria have been around for millions of years, and Homo Sapiens is a relative new-comer, having been on the planet for about 2 to 300 thousand years. That means that viruses and bacteria have been able to adapt to the environment for far longer than we have.

Secondly, the world is awash with viruses and bacteria, in the oceans, on land and carried by almost everything that crawls and walks. The great thing is that most of them do us no harm: in fact we humans have more bacterial cells in and on us, than those cells that make up the human body. Many of them live in the gut and help with digestion: others live on the skin and provide a sort of germ "ground cover" to help protect us from those germs that might cause us harm. One of the problems with the careless use of antibiotics is that these friendly bacteria get killed by antibiotics too, leaving the ground open for those bacteria that are resistant to the antibiotic, and leading to more serious disease.

Thirdly, viruses are totaly different germs to bacteria and need a completely different approach to control. Bacteria are single celled organisms that have DNA within them, and are very similar to human cells. Viruses are more akin to chemicals, having no cellular structure, and need to enter a human cell and hijack the "production line" of that cell to produce more virus particles. Antibiotics do not work against viruses, and should never be offered or used for viral infections. Vaccines are far better at controlling viruses.

By understanding how these germs operate, strategies can be developed to help fight them: and currently, vaccination programs world-wide have probably saved more lives than all the antibiotics used in the last 70 years.

We are still a long way from getting the upper hand in the war against these virulent pathogens, as they are constantly changing and learning from other pathogens, to defeat the body's immune system. Knowing the difference between a virus and a bacteria may help more people understand that antibiotics are not a panacea for "infections" and may well lead to the terrifying situation that we breed out all the antibiotic sensitive bacteria and leave the field open to the resistant ones.
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