PUBLISHED: 23:42 EST, 13 June 2012 | UPDATED: 07:17 EST, 14 June 2012
Humans have more than 10,000 species of germs living in or on them, with scientists claiming bacteria occupy virtually every nook and cranny of our bodies.
New research from the Washington University School of Medicine in St Louis found that even healthy people have thousands of variations of bacteria living up their nose, on their skin and in their guts.
Many of these microbes, as they are known, work to keep us healthy.
But the findings, published on Wednesday in journals Nature and Public Library of Science, show nearly everybody carries around at least low levels of harmful bugs that are linked to specific infections.
When a person is healthy, these nasty germs don’t cause disease, they simply coexist with other microbes in the body.
But researchers have now investigated why some can suddenly turn deadly, by mapping which bugs live where.
‘It’s not possible to understand human health and disease without exploring the massive community of microorganisms we carry around with us,’ said George Weinstock, one of the project’s principal investigators.
‘Knowing which microbes live in various ecological niches in healthy people allows us to better investigate what goes awry in diseases that are thought to have a microbial link, like Crohn’s and obesity, and why dangerous pathogens sometimes, but not always, cause life-threatening illnesses.’
The research, which used a sample of 242 healthy adults, is part of the government’s Human Microbiome Project, a five-year initiative funded with $153 million from the National Institutes of Health and another $20 million from the university.
‘Our bodies are part of a microbial world,’ said Dr Weinstock.
‘You can think of our ecosystems like you do rain forests and oceans, very different environments with communities of organisms that possess incredible, rich diversity.’
The scientists uncovered unique communities of microbes in every site in the body, including the skin, the nose, the mouth and the intestines.
Interestingly, the germs that live on the teeth are different from those in saliva. The most diverse collection of bacteria was found living on the skin, probably because it is the body’s barrier to the outside world.
As part of the project, researchers looked for links between particular types of bacteria in the body and illness.
The findings show that children who developed sudden, unexplained fevers carry more species of viruses in their nose and blood than children without fever.
Although, interestingly, children without fever also carried viruses, though in lower numbers.
Premature babies with life-threatening gastrointestinal illness were found to have ‘quality differences’ in the amount of bacteria in their stools than those who don’t have the disease, opening doors to a prevention or cure.
‘The future of microbiome research is very exciting,’ Dr Weinstock said.
‘This large-scale effort will open doors in many areas of medicine to improve our understanding of good health and the treatment and prevention of disease.’