[Reuters Health, 5 Feb 2007] In research published on Monday in the Proceedings of the National Academy of Sciences, Blaser and his colleagues took swabs from the forearms of six healthy people to study the bacterial populations in human skin --- our largest organ.
"We identify about 182 species," Blaser said in an interview. "And based on those numbers, we estimate there are probably at least 250 species in the skin."
"In comparison," Blaser added, "a good zoo might have 100 species or 200 species. So we already know that there are as many different species in our skin, just on the forearm, as there are in a good zoo."
Not just the skin. I bet that like the digestive tract (your stomach and intestines), hordes and legions of bacteria live in other organs and tissues of the human body. They're just waiting to be discovered.
Sometimes we can think our bodies are forests and the animals roaming it are the bacterial population. How many species you got depends on how clean or how dirty you have become.
Is that ok? Well, like any community, it becomes bad only when the bad citizens outnumber the good ones. That's when the trouble (infection) begins. It's a symbiotic co-existence.
Impact on health? It doesn't always mean that when you try to kill your "bacterial zoo," you will end up infection-free. Some of the good bacteria have a restraining effect on the bad ones, and if you kill the good ones, you end up with the bad bacteria giving you problems.
Likewise, your immune system needs a bit of exercise every now and then. With an ample amount of exposure to bad bacteria, your body develops the immunity it needs against diseases. No exposure means no natural immunity. Though you can resort to vaccination, natural immunity is tougher and better than the passive version.
Enjoy your zoo.