How Contagious Diseases Are Developed

Invasion of microorganisms in body tissues usually starts with attaching them to cells. This is a very specific process requiring bonding by type “lock – key” between human cell and the microorganism.
Microbes may remain around damaged area or spread over other organs – it depends on production by microbes toxins, enzymes and other substances.

Some microorganisms produce toxins that affect near-by or remote cells. As a rule, toxins contain components connected with molecules of some cells (target cells)  where they cause pathological changes. The diseases where toxins play major role are next ones: tetanus, toxic shock syndrome and cholera.

Some contagious diseases are caused by toxins which are produced by microbes out of human body, for example, food intoxication caused by staphylococcus toxins.

Microbes that enter the body to cause a disease must reproduce themselves, after which the situation develops the next way. First, microorganisms while reproduction do overcome body defense mechanisms. The process may be followed by severe damages sometimes leading to death of the human. Secondly, may be achieved condition of balance when the disease turns into chronic form.

This fight wins neither microorganism nor human. Thirdly, human organism with medical treatment or without it may fight pathogenic germs. Thus, lasting immunity is formed and human does not get infection caused by the same microorganism.

Many pathogens exhibit properties that increase disease severity and the ability to stand against protection mechanism of human body. For example, some bacteria produce enzymes that destroy tissues which helps them spread quickly through human body. Sometimes microorganisms may partially block human defense mechanisms disturbing production of antibodies or development of T-cells meant for fighting with them. Other have outer shell that aggravates absorbing the microbe by leukocytes.