Many centuries ago, the existence of the so-called germs was only a theory. But after years of research medical and pharmaceutical research, it has been confirmed beyond any doubt that all around us, we live surrounded by bacteria and viruses, some of which are good for us, some dangerous, and some that protect us but can become pathogens.
So man sought new ways to protect himself from the dangers in the environment. The pursuit of this led to the discovery of the field of epidemiology, a modern science that accounts for the origin of transmissible illness, its production and multiplication based on accurate mathematical formulas.
Bacteria is a class of living organisms that are seen both in the plant and animal world. They are usually one-celled, and co-exist with humans outside the body and also inside. They can be saprophyte that lives on our skin and our nose and are called the human microbiome, or parasite, that are aggressive and try to enter our bodies through multiple ways and multiply.
Saprophyte bacteria of the skin include Staphylococcus, Corynebacterium, Malasezzia, Acinetobacter, Streptococcus and Propionibacterium. They prevent the development of other pathogens, change of the skin pH levels, ferment certain substances and participate on the absorption of vitamins. Sometimes, they can become the parasite and cause infections, for example when they are found elsewhere other than on the skin or when the subject has a suppressed immunity.
In our noses, we have Staphylococcus aureus. In our mouths Streptococcus, Bacteroides, Prevotella, and Fusobacterium. In our pharynx, we have Neisseria, Streptococcus, Haemophilus influenzae. In our colon, there is Bifidobacterium bifides, Bacteroides, E.Coli, Clostridium, Enterobacter, Proteus, Klebsiella and Enterococcus.
So, we can also consider pathogens, that is, bacteria that it is not placed normally in our body or that it is displaced, and all the other bacteria that is not in our bodies, like Mycobacterium for example.
Viruses are all considered pathogens, and their prevention is made through vaccines, even though some of them have such a high rate of mutation that a treatment is impossible at the moment.
Parasites live in the environment and are considered pathogens, but the important fact is that they are transmitted through an intermediary host, usually represented by an animal or a plant. There are several types of worms that can produce sometimes enormous damage to humans. The most common of this is often the tapeworm which lives in the digestive tract and negatively inhibits digestion and absorption of nutrients.
There is also fungus which is both saprophyte and parasite. Candida albicans covers 90% of our body and it is the most important protection barrier, but it can become parasitic when immunity is low. Because the exact fungi cannot be determined sometimes, these infections could lead to other infections and diseases within a human body.
With all of these, the maintenance of environmental isolates becomes even more important due to the multiple threats in the environment. Pharmaceutical research, however, remains ongoing to minimize the impact on the population.