Sources, ways and main mechanism of transmission of infection

Knowing how the spread of infectious diseases occurs will be useful not only for the sake of self-education, but also in order to protect themselves and their loved ones from the disease in case of a risk of infection.

Transmission of infection: stages and sources

The mechanism of transmission of infection is the way that the causative agent of the disease comes from an infected source to a susceptible organism. This process, of course, does not happen simultaneously. First, the pathogen must somehow separate from the infected source, then it remains in the environment or in the animal mediator for a certain period of time and then only in a certain way enters the susceptible organism.

Everything starts from the source. In epidemiology, it is commonly believed that the sources of infection can be only those objects in which natural habitat, reproduction, and then the excretion of pathogens through physiological processes are possible. Infected people or animals are the sources of infection. The mechanism of transmission of infection is determined by the way the disease is transmitted further.

Ways and mechanisms of infection

The routes of transmission of infection are called inanimate objects, which are not the natural habitat of these microbes, but actively participate in their transmission. Basically it is air and water, household items, food and soil - sometimes they are mistakenly regarded as sources of infection. In general, depending on where the pathogen is initially concentrated and where its release occurs, the main mechanisms of infection transmission are identified: aerosol, contact, alimentary, transmission.

Factors of infection

The interaction between microbes and the human body always occurs not in isolation, but in the aggregate of certain factors. Not only the mechanisms and ways of transmission of infection are important, but also the condition at the time of infection of the immune system, the dose of the pathogen, the parameters of the environment and how the pathogenic microbe entered the body.

Each kind of pathogenic microorganisms chooses the most favorable place for themselves in the host's body - one that will provide him with the opportunity of successful life activity, as well as the subsequent release into the environment and distribution. With regard to the penetration of the infection, it is curious that each pathogen has evolved behind its own, often only, "entrance doors." It can be mucous membranes of both respiratory and digestive systems, damaged skin and urogenital system. The disease will not develop if its pathogen gets into the human body, not through its own, but through "strange", uncharacteristic gate.

It is also interesting that, in order for the disease to arise, a certain number of its pathogens is required. The infectious dose for each pathogen is different.

Aerosol mechanism

This is the most common mechanism of transmission of infection. Sometimes it is also called respiratory, aspiration or aerogenic, but more often this method is called airborne. This name well characterizes the way in which the pathogens of infections are transmitted in this case. Initially, viruses or bacteria are concentrated in the mucous membranes of the respiratory tract, and when sneezing, coughing or talking, along with droplets of saliva and mucus are released into the surrounding air. After being in it in the form of an aerosol for a while, the pathogens along with the flow of inhaled air enter a susceptible organism. And if drops of a relatively large size quickly settle, then fine-dispersed aerosols can remain active for a long time and move for significant distances. It should be clarified that pathogens can be found not only in droplets, but also in dust particles. This applies to those pathogens that are resistant to drying.

Alimentary (food) mechanism

In this case, in an infected organism the infection is localized in the intestine and is released into the environment with the products of vital activity. Infection is already carried out through the mouth, usually with infected food and water. Infection in them can get from dirty hands, through the use of meat and milk of infected animals, through insects. This path is known more as a fecal-oral mechanism for the transmission of an infectious agent - also a "talking" name.

Contact Path

Another fairly common mechanism for transmission of infection. Pathogens of the disease can be on the skin, mucous membranes, wounds. It is interesting that these pathogens are highly susceptible to environmental conditions, therefore, for infection, they need direct contact directly with infected tissues. However, infection can also happen through various objects. These can be bacterial, viral, fungal infections, as well as parasitic diseases.

Special variants of the contact mechanism

Often these ways of infection are generally isolated in separate groups. But, strictly speaking, they are only special cases of the contact mechanism already described. We are talking about the sexual, gemokontaktnom and vertical pathways of infection. Sexual pathway involves infection when contact with the mucous membranes of the urogenital system. The hemocontact path is the infection through the infected blood of the source, when it hits the bloodstream of a healthy person. This can happen during a blood transfusion, for example, or with medical manipulations involving damage to the skin or mucous membranes with non-sterile instruments. The vertical path is called so because this mechanism of transmission of infection ensures the transition of the causative agent from one generation to another when the disease is transmitted either through the placenta during pregnancy or during delivery.

The transmissible mechanism of infection

With this mechanism, the pathogen is in the blood of the source, and it is realized by means of insects, namely bloodsucking: mosquitoes and mosquitoes, lice, ticks, fleas. In this case, insects serve as living transmission factors. And in the body of some of them there is simply an accumulation of pathogens, in others - a cycle of their development and reproduction takes place. It is logical that the degree of infestation is directly proportional to the size of the insect population. Infection usually occurs directly in the process of biting, but the probability of penetration of pathogens into damaged skin is great if the insect is crushed.

I must say that the above classification of the mechanisms of transmission of infectious agents is to some extent conditional. So, some sources do not distinguish the transmissible mechanism in a separate group, but consider it to be a variant of the blood-contact pathway. Transmission of infection through syringes and other non-sterile medical instruments is sometimes also quite logically referred to the transmissive mechanism, as well as the intrauterine route.

Examples of infectious diseases, depending on the mechanisms of their transmission

The number of microorganisms on Earth is estimated at millions. Bacteria, viruses, fungi - many of them are harmless, while others cause quite dangerous diseases. Sources, mechanisms and ways of transmission of infection in cases of different diseases are different. All of them are unlikely to be listed, but the most common ones are to know, as well as the possible ways of infecting their pathogens.

So, the airborne way is transmitted: influenza, scarlet fever and chicken pox, rubella and measles, as well as meningitis, tonsillitis, tuberculosis and others. With regard to fecal-oral, it is usually a mechanism for the transmission of intestinal infections: cholera, dysentery, hepatitis A, etc. In the same way, polio is infected. Diseases transmitted by contact are various skin infections, tetanus, venereal diseases, anthrax. Finally, by transmigration - through the bites of insects-bloodsuckers - malaria, typhoid, plague, and encephalitis are transmitted. Of course, not everything is so simple, and many infectious diseases are transmitted through not one but several mechanisms.

Prevention

Observance of the simplest rules of personal hygiene is one of the simplest and most reliable means for protecting against infectious diseases, especially those transmitted by alimentary methods. You can not neglect careful washing and sufficient heat treatment of food. The worst enemies of the spread of diseases transmitted through the air are airing the premises, isolating the sick, using medical masks, if necessary, to contact them. To prevent infection through the blood, it is necessary, as far as possible, to carefully choose medical institutions, tattoo parlors and beauty salons. A lot has already been said about the prevention of sexually transmitted infection. Well, in the end, we can not fail to mention the full strengthening of immunity. The disease is easier to prevent than to treat it later.