Ways and methods of transmission of infection

In the surrounding world, there is a huge number of microorganisms that are invisible to the human eye. Some of them represent no danger, while others can cause various diseases. What ways and ways of transmission of infection exist - a question that deserves attention.

Infection: mechanism and route of transmission. Explanations of terms

In such a science as epidemiology, the concept of "infection" is used. This term indicates the danger of infection of a plant, animal or human organism with various pathogenic pathogens. These include protozoa, bacteria, viruses, etc. Infections are transmitted in accordance with certain mechanisms. By them is meant a combination of specific methods of moving pathogens from a source into a receptive organism.

Specialists identify 4 mechanisms for transmission of infection :

• Fecal-oral;
• Aerosol-aerogenic;
• transmissible;
• Hemocontact.

Each mechanism is implemented in different ways (ways). This term refers to factors that ensure the penetration of infection into a susceptible organism under certain conditions.

Transmission routes, characteristic for the fecal-oral mechanism

Infections characteristic of this mechanism of transmission are called intestinal infections. The causative organism lives in the digestive system of the host. In the environment, microorganisms get along with feces. In the new organism, pathogens penetrate in various ways. Here are ways to transmit intestinal infection:

• Water (with the use of contaminated water);
• Food (through eggs, meat, fish, milk, contaminated vegetables, fruits and berries);
• Contact-household (through various household items).

In the water microorganisms are due to the direct ingress of feces or contaminated soil into it. With food and contact-household transmission routes, food and household items often become infected after a sick person who serves as a source of infection touches them. Flies play an important role in the transmission of pathogens. Pathogenic microorganisms fall on the feet of insects with feces.

An example of an infection with a fecal-oral transmission mechanism

One of the known human diseases is dysentery. This is a disease characterized by syndromes of gastrointestinal lesions and general infectious intoxication. The disease occurs due to dysentery sticks belonging to the genus Shigella. Ways of transmission of infection - water, food and contact-household.

At present, dysentery is diagnosed in isolated cases. Infection occurs:

• Because of the use of water from the river, wells, columns in an unsatisfactory sanitary condition;
• The use of insufficiently processed food (dirty, raw).

Possible outbreaks - group diseases. Water epidemics are caused by violations of decentralized and centralized water supply. Contact-household outbreaks often occur in pre-school institutions because of the violation of the anti-epidemic regime (for example, because of poorly performed disinfection measures).

Ways of transmission of infection with an aerosol-aerogenic mechanism

This transmission mechanism has several names. In the specialized literature one can find such names as aspirating, aerosol, and drop. Analyzing them, it can be understood that the aerosol-aerogenic mechanism of transmission is characterized by localization of the pathogen in the organs of the respiratory system.

Microorganisms can be transmitted in the following ways (ways):

1. Air-drip. The causative agent is excreted by coughing, sneezing, or talking. Droplets of infected mucus enter the environment, and then with air penetrate into the organisms of healthy people.
2. Air-dusty. With this method of transmission, a healthy person becomes infected after exposure to particles of suspended dust containing the infection.

Examples of diseases with aerosol-aerogenic transfer mechanism

Influenza is a common disease of the viral nature. The main way of transmission is airborne. When the disease affects the upper respiratory tract. When the virus enters the body of a healthy person, symptoms such as weakness, headaches, muscle and joint pains appear. The body temperature rises. After a while, patients begin to complain of nasal congestion, sore throat, dry cough.

Air-dust transmission is inherent in scarlet fever, a streptococcal infection characterized by a small-point rash, sore throat and signs of general intoxication. When the disease pathogens are released from the body of a sick person with phlegm, pus. They are very resistant to environmental factors. This explains the possibility of infection through air and dust.

Ways of transmission of infection with the transmission mechanism

For the transmissive mechanism of transmission, the presence of pathogens in the host's blood is characteristic. In a healthy organism, the infection is due to arthropods (fleas, lice, mosquitoes, mites, flies). Carriers are divided into specific and nonspecific. The first group includes such arthropods, which suffer certain diseases. For example, mosquitoes act as specific carriers of malaria, typhus is lice. The second group includes flies carrying acute intestinal infections, typhoid fever, hepatitis A.

The transmission mechanism can be transmitted:

• Anthroponosis (only a person serves as a reservoir and source of infection);
• Zoonoses (the reservoir and source of infection are animals);
• Anthropozoonosis (the source of infection can be both animals and people).

Examples of diseases with a transmissive transfer mechanism

One of the transmissible infections is malaria. This anroponotic disease, the causative agents of which are the simplest of the genus Plasmodium. Pathogenic microorganisms are transmitted from sick people to healthy through mosquitoes belonging to the genus Anopheles. The new owner becomes infectious only when the genital forms of the pathogen appear in the blood - gametocytes. For example, with tropical malaria it occurs about a week after the beginning of parasitemia and lasts throughout the year.

Another example of a disease with a transmissible transmission mechanism is the plague. The causative agent is Yersinia pestis (a fixed bacterium having the shape of a rod). The source of infection in nature are rodents, and the carrier - fleas. In these blood-sucking insects, after using contaminated blood in the digestive system, a plague microbe begins to multiply. Pathogens accumulate and fill the lumen of the digestive tube. With subsequent bites of animals or humans, fleas regurgitate agents and thus provide infection.

The transmission paths inherent in the hemocontact mechanism

The hemocontact transfer mechanism is characteristic for many infections: bacterial, fungal, viral, protozoal, parasitic. Pathogens enter the body in many ways. For this reason, the following ways of transmission of infection are distinguished:

• vertical;
• Parenteral;
• Transplantation;
• sexual.

The vertical mode of transmission of infection is explained by the penetration of the pathogen into the body of the fetus from the body of the pregnant woman through the placenta. The parenteral method is characterized by medical manipulation. For example, in some cases, people become infected in the dental office when the doctor uses non-sterile instruments. The transplantation method of transmission of infection is realized when internal organs are transplanted. The latter path is inherent in diseases transmitted through sexual intercourse.

In addition, it is possible to identify a contact mode of transmission of infection. When it is infected, it occurs by direct contact with the source of pathogens and the introduction of mucous membranes and skin on the surface (for example, with scabies)

An example of a disease with a hemocontact transfer mechanism

The current medical and social problem is that many people do not know or ignore the ways of transmission of sexual infections, are not protected during casual relationships. That's why STDs are very often diagnosed by doctors.

An example of an infection with a blood contact mechanism is HIV. This disease affects the immune system. It is gradually destroyed before the formation of AIDS (acquired immunodeficiency syndrome). The causative agent is a virus from the family of retroviruses. The source of infection is a sick person.

Sexual and vertical modes of transmission of infection are the main (natural) in this disease. The artificial route of transmission (parenteral and transplantation) is also actively implemented. With it, the virus penetrates through damaged skin and mucous membranes during therapeutic and diagnostic procedures, the introduction of drugs, the performance of tattoos in non-sterile conditions.

Intrahospital infections

Particular attention should be given to nosocomial infections (VBI). This is a very serious problem. When VBI people become infected when they go to the hospital or seek medical help. Intrahospital infections cause significant damage to health. In addition, they increase the duration of treatment and stay in a medical institution, cause complications, and sometimes even lead to death.

Methods of transmission of infection in a medical institution are diverse. Pathogens fall into the human body as natural (fecal-oral, aerosol-aerogenic), and artificial (during invasive medical and diagnostic procedures) ways. Hospital-acquired infections occur not only because of non-observance of the sanitary and hygienic and anti-epidemic regimen, but also because of the emergence of microorganisms resistant to chemotherapy, antibiotics and adverse environmental factors.

In conclusion, it should be noted that for each disease there are certain ways (ways) of transmission of infections. Knowing how the infection occurs, you can prevent the occurrence of some ailments (for example, do not use dirty products, avoid accidental sexual contacts, lead a healthy lifestyle and give up drugs).