In the middle of the last century, humanity has achieved some success in the fight against certain infections. But, as it turned out, it is too early to celebrate the final victory over such a scourge as infectious diseases. Their list includes more than 1200 items, and is constantly updated with newly discovered diseases.
How infectious diseases were studied
Mass diseases have been known to man since ancient times. There is evidence that as early as the 5th century BC. philosophers and doctors suspected the existence of some tiny, invisible to the eye living organisms that can cause diseases that are characterized by rapid spread and high mortality. During the Middle Ages, however, these materialistic views were forgotten, and outbreaks of mass diseases were explained solely by God's punishment. But the fact that the sick should be isolated, as well as to destroy infected things, buildings and corpses, was already known then.
Knowledge accumulated gradually, and the middle of the 19th century was marked by the birth of such a science as microbiology. Then the causative agents of many diseases were discovered: anthrax,cholera, plague, tuberculosis and others. Infectious diseases have since been separated into a separate group.
Terminology
The word "infection" in Latin means "contamination", "infection". As a biological concept, this term refers to the penetration of a microscopic pathogen into a more highly organized organism. It can be either a person or an animal, or a plant. Then the interaction between the systems of the micro- and macroorganism begins, which, of course, does not occur in isolation, but under specific environmental conditions. This is a very complex biological process, and it is called infectious. As a result of such interaction, the macroorganism is either completely freed from the causative agent of the disease, or dies. The form in which the infectious process manifests itself is the specific infectious disease.
Common characteristics of infectious diseases
We can talk about the beginning of an infectious disease if, after a meeting of a pathogen and a macroorganism, in particular a person, the vital functions of the latter are disturbed, symptoms of the disease appear, and an increase in antibody titer occurs in the blood. There are other forms of infectious processes: he althy carriage of the virus in the presence of immunity or natural immunity to this disease, chronic infections, slow infections.
In addition to the fact that all infectious diseases begin with pathogenic pathogens, there are other common characteristics. Such diseasescontagious, that is, they can be transmitted from a sick person or animal to a he althy one. Under certain conditions, epidemics and pandemics may occur, that is, the mass spread of the disease, and this is already a very serious threat to society.
Besides this, infectious diseases, a list of which can be found in any medical reference book, always proceed in cycles. This means that in the course of the disease, certain time intervals alternate in turn: the incubation period, the stage of the precursors of the disease, the period of the peak of the disease, the period of decline and, finally, the recovery period.
The incubation period has no clinical manifestations yet. It is the shorter, the higher the pathogenicity of the pathogen and the greater its dose, and can be as short as several hours, or several months and even years. Harbingers of a disease are the most common and rather vague symptoms, on the basis of which it is difficult to suspect a specific infectious disease. Typical for her clinical manifestations are maximum at the stage of the peak of the disease. Further, the disease begins to fade, but some infectious diseases are characterized by relapses.
Another specific characteristic of infectious diseases is the formation of immunity during the disease process.
Infectious pathogens
The causative agents of infectious diseases are viruses, bacteria and fungi. In order for the introduction to be successful for a pathogenic microorganism, one meeting of the macro- and microorganism is not enough. Requires the fulfillment of certain conditions. Of great importance is the actual state of the macroorganism and its defense systems.
A lot depends on the pathogenicity of the pathogen itself. It is determined by the degree of virulence (toxicity) of the microorganism, its toxigenicity (in other words, the ability to produce toxins) and aggressiveness. Environmental conditions also play a big role.
Classification of infectious diseases
First of all, infectious diseases can be systematized depending on the pathogen. In the general case, isolated viral, bacterial and fungal infections. Separately, chlamydial, mycoplasmal, rickettsial, spirochetal infections are distinguished, although chlamydia, and mycoplasmas, and rickettsia, and spirochetes belong to the kingdom of bacteria. Viruses are perhaps the most common pathogens. However, bacteria can also cause many diseases. Among the most famous are such as tonsillitis, meningitis, cholera, plague, bacterial pneumonia, tuberculosis, tetanus. Fungal infectious diseases, or mycoses, include candidiasis, dermatophytosis, onychomycosis, lichen.
Most often, infectious diseases are classified according to the localization of pathogens, taking into account the mechanism of their transmission, but this applies to those diseases that spread from person to person. Accordingly, intestinal infectious diseases transmitted by the fecal-oral route (astrovirus infection, poliomyelitis, cholera, typhoid fever) are distinguished. There are infectious diseases of the upperrespiratory tract. The method of infection with them is called airborne (SARS, diphtheria, scarlet fever, influenza). Infectious diseases can still be localized in the blood and transmitted through insect bites and medical procedures. We are talking about injections and blood transfusions. These include hepatitis B, plague, typhus. There are also external infections that affect the skin and mucous membranes and are transmitted by contact.
In the process of evolution, each type of pathogen of an infectious disease has its own entrance gate of infection. So, a number of microorganisms penetrate through the mucous membranes of the respiratory tract, others - through the digestive tract, genital tract. It happens, however, that the same pathogen is able to enter the human body at the same time in different ways. For example, hepatitis B is transmitted through blood, from mother to child and by contact.
As for the sources of infection, there are anthroponoses, if the disease comes from a person, and zoonoses, if the carriers of the infection are animals. I must say that the pathogens of zoonoses, when they enter the human body, are no longer released into the environment, therefore the intensity of the spread of zoonoses is an order of magnitude lower than that of anthroponoses. Zoonoses include brucellosis, botulism, plague, tularemia, rabies, anthrax, foot-and-mouth disease, tetanus. Zoonoses typically have multiple transmission mechanisms.
There are three main habitats for infectious agents. It's an organismhuman, animal organism and inanimate environment - soil and water bodies.
Symptoms of infectious diseases
Common symptoms of infectious diseases include malaise, headache, pallor, chills, muscle aches, fever, sometimes nausea and vomiting, and diarrhea. In addition to the general ones, there are symptoms that are characteristic of only one disease. For example, a meningococcal rash is very specific.
Diagnosis
As for the diagnosis, it should be based on a comprehensive and comprehensive study of the patient. The study includes a detailed and thorough questioning, examination of organs and systems, and an analysis of the results of laboratory tests. Early diagnosis of infectious diseases presents certain difficulties, but is of great importance both for the timely adequate treatment of the patient and for the organization of preventive measures.
Treatment
There are several directions in the treatment of ailments such as infectious diseases, the list of which is so frighteningly extensive. First of all, these are measures aimed at reducing the activity of a pathogenic microorganism and neutralizing its toxins. For this, antibacterial drugs, bacteriophages, interferons and other agents are used.
Secondly, it is necessary to activate the body's defenses by using immunomodulatory drugs and vitamins. Treatment must be comprehensive. It is important to normalize the functions of organs and systems disturbed by the disease. In anycase, the approach to treatment should take into account all the individual characteristics of the patient and the course of his disease.
Prevention
In order to protect yourself and your loved ones as much as possible from such a threat as infectious diseases, the list of which includes diseases of a viral, bacterial and fungal nature, you must remember about quarantine measures, vaccination, and strengthening the immune system. And sometimes, to escape from infection, it is enough to follow the basic rules of personal hygiene.
