More than 600 species of known microorganisms constantly live in our language, but we are more likely to catch the infection in public transport. What is the source of the infectious disease? How does the infection mechanism work?
Pathogenicity of organisms
Infection with pathogens is called infection. The term appeared back in 1546 thanks to Girolamo Fracastoro. Currently, science knows about 1,400 microorganisms, they surround us everywhere, but infections do not develop in us every second.
Why? The fact is that all microorganisms are divided into pathogenic, conditionally pathogenic and non-pathogenic. The former are often parasites, and require a "host" for their development. They can affect even a healthy and resistant body.
Conditionally pathogenic microorganisms (E. coli, Candida fungus) do not cause any reactions in a healthy person. They can live in the environment, be part of the microflora of our body. But under certain conditions, for example, with weak immunity, they become pathogenic, that is, harmful.
The term "non-pathogenic" implies the absence of danger when interacting with these organisms, although they can penetrate the human body and cause the development of infection. The boundaries between opportunistic and non-pathogenic microflora in microbiology are extremely blurry.
Source of infection
Infectious disease can be caused by the penetration of pathogenic fungi, viruses, protozoa, bacteria, prions into the body. The source of infectious agents is the environment that contributes to their development. Such an environment is often a person or animal.
Once in favorable conditions, microorganisms actively multiply, and then leave the source, appearing in the external environment. Pathogens, as a rule, do not reproduce there. Their number gradually decreases until they disappear completely, and various adverse factors only accelerate this process.
Resume the activity of microorganisms when they find a new "owner" - a vulnerable person or animal whose immunity is weakened. The cycle can be repeated continuously while the infected ones spread the parasites to healthy organisms.
Environment as a transmitter
It is important to understand that the environment is not a source of infection. She always acts only as an intermediary for the transmission of microorganisms. Insufficient humidity, lack of nutrients and inappropriate ambient temperature are unfavorable conditions for their development.
Air, household items, water, soil themselves are first infected, and only then they transport parasites to the host’s body. If microorganisms have been in these environments for too long, they die. Although some have a special resistance and can be stored even in adverse conditions for many years.
The pathogen of anthrax has strong resistance . It persists in the soil for several decades, and when boiled, it dies only after an hour. He is also absolutely indifferent to disinfectants. The causative agent of cholera El Tor is able to persist in soil, sand, products and feces, and heating the reservoir to 17 degrees allows the sticks to multiply.
Sources of infection: types
Infections are divided into several types, in accordance with the organisms in which they multiply and to whom they can be transmitted. Based on these data, anthroponoses, zooanthroponoses and zoonoses are distinguished.
Zooantronoses or anthropozoonoses cause diseases in which the source of infection is a human or animal. In humans, infection most often occurs through animals, especially through rodents. Zoonotic infections include rabies, glanders, tuberculosis, leptospirosis, anthrax, brucellosis, trypanosomiasis.
Anthroponic disease is when a person is a source of infection, and it can only be transmitted to other people. This includes relapsing, rash, and typhoid fever, chickenpox, gonorrhea, flu, syphilis, whooping cough, cholera, measles, and polio.
Infectious diseases are called zoonoses, for which the animal organism is a favorable environment. Under certain conditions, the disease can be transmitted to people, but not from person to person. The exceptions are plague and yellow fever, which can circulate among people.
Infection detection
An infected person or animal can cause a wide spread of the disease within one, several settlements, and sometimes several countries. Dangerous diseases and their spread are studied by epidemiologists.
If at least one case of infection is detected, doctors will find out all the details of the infection. The source of the infection is identified, its type and distribution methods are determined. For this, an epidemiological history is most often used, which consists in interviewing the patient about recent actions, contacts with people and animals, and the date of the onset of symptoms.
Complete information about the infected is extremely useful. With its help, it is possible to find out the route of transmission of the infection, the possible primary source, as well as the potential scale (whether the case will become single or massive).
The initial source of infection is not always easy to identify, there may be several. This is especially difficult to do with anthropozoonosis diseases. In this case, the main task of epidemiologists is to identify all potential sources and routes of transmission.
Transmission methods
There are several transmission mechanisms. Fecal-oral is characteristic of all intestinal diseases. Malicious microbes are found in excess in feces or vomit; they enter a healthy body with water or in a contact-household way. This happens when the source of infection (a sick person) does not wash his hands well after using the toilet.
Respiratory, or airborne, is for viral infections that affect the airways. The transfer of microorganisms occurs when sneezing or coughing near uninfected objects.
Transmissible means the transmission of infection through the blood. This can happen when bitten by a carrier, such as a flea, tick, mosquito, lice. Contact pathogens are transferred that are located on the skin or mucous membranes. Penetrate into the body through wounds on the body or while touching the patient.
Sexually transmitted diseases are mostly sexually transmitted diseases, usually directly through sexual contact. The vertical transmission mechanism is the infection of the fetus from the mother during pregnancy.
Specificity of transmission of infection
Each type of microorganism has its own mechanism, due to which viruses or bacteria enter the host organism. As a rule, there are several such mechanisms, and certain environmental factors can sometimes contribute to the transmission of parasites.
At the same time, a method that is suitable for some microbes does not contribute to the transfer of others at all. For example, many pathogens of respiratory infections are completely powerless in front of gastric juice. Getting into the gastrointestinal tract, they die and do not cause the development of the disease.
Some mechanisms of harmful microbes entering the body can, on the contrary, accelerate the development of the disease. So, the entry of the causative agent of syphilis into the bloodstream using an infected medical needle causes complications. The disease is more intense.
Conclusion
Infection is a combination of biological processes that occur and develop in the body when pathogenic microflora are introduced into it. An ailment can affect both a person and an animal. The main transmission mechanisms are contact, genital, airborne, fecal-oral, vertical routes.
The source of infection is an environment favorable for the reproduction and spread of microbes. Suitable conditions are often possessed by people and animals. The environment, as a rule, acts as an intermediary.
It usually does not have the conditions for the life of pathogenic and opportunistic microorganisms. Long stay in the environment contributes to their extinction. In some cases, microorganisms are able to persist in soil, water, sand from a few days to decades.