More contagious than micro-organisms are fear and hopelessness.
Long before our time, the existence of micro-organisms was presupposed, notably in Jainism, whose followers vow non-violence in thought and practice (Ahimsa) towards all living beings. The tradition is said to be older than Buddhism. 
In the teachings of Mahavira (599 – 527 BEC), micro-organisms are described as unseen creatures living in earth, water, air and fire, and existing as clusters pervading every plant and tissue, not just on earth but throughout the whole universe. Jain libraries are the oldest in India.
While home-bound with a young child in rural Somerset, I did an OU course on world religions, wanting to learn about the formative ideas underlying our variety of cultures. Reading on Jainism, I was struck by its beautiful philosophy, genuine tolerance of other faiths, and the surprisingly modern belief – that the universe is self-regulated by the laws of nature. Worth exploring: see wiki-link below.
With a different mind-set, the idea of unseen creatures informed a nasty biological war fare during the Middle Ages, when diseased corpses were catapulted into enemy strongholds.
Along came artificial eyes, the telescope and the microscope, evidencing these unseen worlds. The Jesuit priest, Athanasius Kircher, and Anton van Leeuwenhoek, were among the first to spot micro-organisms through lenses in the 17th century. 
The journey took off, until Ferdinand Cohn founded the discipline of bacteriology in the 19th century, and Louis Pasteur and Robert Koch developed the study of microbiology, focussing on food preservation and vaccines. The gained knowledge helped to protect us from organisms known to spread disease, and improved the hygiene of our environment. During the late 19th century the study was expanded through the work of Martinus Beijerinck and Sergei Winogradsky into the field of general microbiology.
Today the study of micro-organisms has developed to such extend that hundreds of specialised branches of study exist serving a huge variety of applications. I’m fascinated by biology, and I greatly respect scientists who devote their days and nights to deepen our understanding of life.
What I question, as do many of my friends, which include scientists, is the unrestricted power of multinational companies. It is totally unethical that multinationals can push decisions as to how scientific evidence is used. To start with, they must be made accountable for damages caused, and next, it should be obligatory, like a tax, that a fraction of the profits these companies reap be used for interdisciplinary research, so that evidence can be established for the many undeniably wholesome methods of balancing and strengthening self-organising systems.
The over-reliance on suppressive drugs (and in the case of agriculture pesticides) in the fight against every imbalance has devastating side effects. Apart from training super-bugs, the relentless war undermines the ecosystem of our planet, and our birth right, the ingenious self-regulatory system that acquires immunity through exposure. Nature has taught us everything, nature is not the enemy. Excess use of medication could even undo the good work of vaccines, meant to help us acquire immunities. A weakened immune system may eventually fail to deal with any kind of exposure. So why do we sanction this paranoid warfare ?
What is known about micro-organisms includes the process of endosymbiosis – where symbiosis occurs between different organisms that benefit from living together. Lynn Margulis opposed the neo-Darwinian concept of competition, and proposed that evolution thrived through cooperation: ‘Symbiogenesis recognizes that every visible life-form is a combination or community of bacteria.’ (See link below) In other words, the fittest is what adapts and harmonises.
There is always more than one way to look at something. When it comes to the prevention of dis-ease, and the healing of body and mind, the soothing of stress, we have enough knowledge and wisdom to appreciate the effectiveness of: relaxation, telling one’s story and being listened to, a clear positive intention, the benefits of meditation, a calm mind, the balancing of subtle energies, the vibrations of harmonious sound, architecture, colours, symbolic understanding, the use of active creative imagination, a gentle touch, a heartfelt smile, for example.
The authenticity of a friend, a doctor, a healer or therapist, can inspire a troubled person who is seeking support to take self-responsibility. Trust, or faith in one’s healing, is a phenomenon that also throws light on the powerful physiological effects of the placebo, which is a proposed ritual that promises nothing, but puts the patient in charge. Wow!
From another tradition that respects all faiths, here is a perspective on microbes expressed by Sufi Hazrat Inayat Khan, who brought his wisdom to the west in the early 20th century:
Every day a new invention brings a new microbe. And if a new microbe is discovered every day till the end of the world there will be numberless diseases; in the end it will be difficult to find one man healthy, for there must always be some microbe; if it is not of an old disease, then of a newly discovered one …
The people of old thought that microbes were spirits, living beings, in the absence of science which today distinguishes these spirits in the form of microbes; and yet it seems that the ancient healers had a greater grip upon the illness, for the reason that they considered the microbe in its spirit. In destroying the microbe they did not only destroy the outer microbe, but the inner microbe in the form of the spirit, of the germ; and the most interesting thing is that in order to drive away that spirit which they thought had possessed the patient, they burned or they placed before him certain chemicals which are used even now, having been proved to be destructive to the germs of diseases.
With every measure that physicians may take to prevent the germs of diseases from coming, in spite of all the success that they will have there will be a greater failure; for even if the actual germ is destroyed, it exists, its family exists, somewhere. Besides, the body which has once become the abode of that particular germ has become a receptacle of the same germ. If the physician destroys the germ of disease from the body of an individual that does not mean that he destroys it from the universe. This problem, therefore, must be looked at from another point of view: that everything that exists in the objective world has its living and more important part existing in the subjective world; and that part which is in the subjective is held by the belief of the patient. As long as the patient believes that he is ill he is giving sustenance to that part of the disease which is in the subjective world. Even if the germs of the disease were destroyed, not once but a thousand times in his body, they would be created there again; because the source from which the germs spring is in his belief, not in his body, as the source of the whole creation is within, not without.
Hazrat Inayat Khan
The outer treatment of many such diseases is just like cutting the plant from its stem while the root remains in the ground. Since the root of the illness is in the subjective part of one’s being, in order to drive away that illness one must dig out the root by taking away the belief of illness even before the outer germ is destroyed. The germ of illness cannot exist without the force, the breath, which it receives from the subjective part of one’s being; and if the source of its sustenance is once destroyed, then the cure is certain.
Very few people can hold a thought, but many are held by a thought. If such a simple thing as holding a thought were mastered, the whole life would be mastered. When once a person gets into his head, ‘I am ill’, and when this is confirmed by a physician, then his belief becomes watered like a plant, then his continual reflection of it, falling upon his illness like the sun, makes the plant of illness grow; and therefore it would not be an exaggeration to say that, consciously or unconsciously, the patient is the gardener of his own illness … The root of illness is in the mind, and if that root is continuously watered by thought and feeling, illness is realized in the end.
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More contagious than micro-organisms are fear and hopelessness. (my conclusion)
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We are the mirror and the face in it.
We are tasting the taste this minute
of eternity. We are pain
and what cures pain. We are
the sweet, cold water and the jar that pours.
Rumi – transl. by John Moyne and Coleman Barks
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Jainism: http://en.wikipedia.org/wiki/Jainism
Lynn Margulis
http://discovermagazine.com/2011/apr/16-interview-lynn-margulis-not-controversial-right
Hazrat Inayat Khan – Volume 4 – Healing and the Mind World.
Course of Mirrors 