What is infectious diseases?

Infectious diseases (“infectio” – infection) – a group of diseases that are caused by the penetration into the body of pathogenic (pathogenic) microorganisms.
In order for a pathogenic microbe that enters the body to cause infectious diseases, it must be able to overcome the resistance of the human body and have a toxic effect on it.
These qualities experts call virulence (toxicity).
Some pathogenic microorganisms release toxins (endotoxins), in the process of self-destruction (typhoid fever, cholera).
Other pathogens of infectious diseases secrete toxins (exotoxins) in the process of their life (diphtheria, tetanus).

The share of infectious diseases accounts for 20-40% of the total number of all human diseases.
The study, prevention, diagnosis and treatment of infectious diseases are engaged in such microbiological and medical disciplines as urology, venereology, epidemiology, therapy, gynecology, phthisiology, immunology, otolaryngology, virology and, of course, the section of medicine “infectious diseases”.

To date, the number of infectious diseases known to science exceeds 1200, and this figure is constantly increasing.
A person throughout his life is in contact with countless microorganisms. However, only 1/30,000 of the microbes are infectious agents.
These are fungi, bacteria, rickettsiae and viruses that have pathogenic properties.
The intensity of the spread of infectious diseases depends mainly on social and domestic factors: working conditions, nutrition, housing conditions, cultural and economic level of the population.

The process of infectious diseases:

Infectious diseasesinfectious diseases differ from non-infectious diseases in that the pathogenic agent and the body in infectious diseases have a certain biological activity.
A pathogenic microorganism is a powerful irritant, as a result of which a complex process occurs on the body.
From the very beginning of this process, it distinguishes two main links – the physiological state of the body and the causative agent of an infectious disease.
The ratios between these links in each case may be different depending on the stage, phase, period of development of the infectious process.
It should be borne in mind that not only patients, but also recovering from infectious diseases, people can serve as sources of pathogens (with intestinal infections, diphtheria and some others).
Some people may be carriers of the infection without hurting themselves.

In the development of the pathological process, there are several main stages:

  • the moment of infection – there is a penetration of pathogenic microbes into the body;
  • incubation (hidden, latent) period – lasts from the moment of infection to the manifestation of the first symptoms of the disease;
  • prodromal period (harbinger of the disease) – accompanied by a slight increase in temperature, headache, feeling of weakness, general malaise;
  • the period of increase in the disease – there is a consistent appearance of signs characteristic of a particular disease;
  • the height of the disease – the time of pronounced manifestation of all symptoms specific to the disease;
  • the period of extinction of the disease – accompanied by the disappearance of clinical signs of the disease with a rapid (crisis) or slow (lysis) drop in temperature;
  • recovery period – the duration depends on the general condition of the body, the conditions in which the patient is, the severity of the disease.

Many infectious diseases of a person (smallpox, typhus, influenza, scarlet fever, diphtheria, etc.) are characterized by the development of complications during the period of the disease.
After an infectious disease, a person for some time or forever becomes immune to the effects of its pathogens (acquires immunity).

Classification of infectious diseases

Infectious diseases of a person, depending on a certain mechanism of transmission and the place of preferential localization of the process, are divided into the following groups:

  • intestinal – salmonellosis, cholera, dysentery, paratyphoid A and B, food toxicoinfections, escherichiosis, typhoid fever;
  • respiratory tract infections – chickenpox, SARS, measles, influenza, mycoplasma respiratory infection;
  • transmiss, or blood, infections – malaria, plague, recurrent and typhus, HIV infection;
  • infectious diseases of the outer covers – tetanus, anthrax;
  • infections with multiple routes of transmission – infectious mononucleosis, enterovirus infections

By the nature of pathogens, infectious diseases are divided into:

  • viral – measles, influenza, parainfluenza, HIV infection, viral hepatitis, meningitis, cytomegalovirus infection;
  • prion – fatal familial insomnia, kuru, Creutzfeldt-Jakob disease;
  • protozoal – critosporidiosis, amebiasis, isosporiasis, babesiosis, toxoplasmosis, blastocystosis, malaria, balantidiaz;
  • bacterial – cholera, plague, dysentery, staphylococcal and streptococcal infections, salmonellosis, meningitis;
  • mycoses (fungal infections) – epidermofitia, aspergillosis, candidiasis, mucormikoz, cryptococcosis, chromomycosis.

Infectious diseases are also divided into zoonotic and anthroponotic.
Zoonoses include animal diseases, the causative agents of which can enter the human body and infect it (rabies, anthrax, tularemia, foot-and-mouth disease, brucellosis, leptospirosis, listeriosis). Anthroponosis is exclusively human diseases and is transmitted between people (measles, typhus, cholera, dysentery, smallpox, typhoid fever, diphtheria).
Caused by parasites (pathogens of animal origin – insects, protozoa, mites) diseases are called parasitic, or invasive.

Among all infectious diseases, a number of especially dangerous infections are distinguished, called quarantine.
They are characterized by a tendency to rapid spread, a high degree of contagiousness, a severe epidemic course and a high risk of rapid death.
The World Health Organization includes smallpox (considered eradicated in the world since 1980), plague, yellow fever (and similar to it in the epidemiology of Marburg and Ebola), cholera.
In Russia, anthrax and tularemia are also considered especially dangerous infectious diseases.

Methods of infection, treatment and prevention of infectious diseases

Treatment and prevention of infectious diseasesTreatment of infectious diseases is usually carried out in specialized departments of hospitals, in mild cases, treatment at home is possible.
Strict compliance with the anti-epidemic regime is a prerequisite.
Modern medicine has created and successfully uses a large number of effective medicines.
These are antibiotics, vaccines (used for the prevention of infectious diseases), immunoglobulins of various kinds, bacteriophages, etc.

Prevention of infectious diseases is no less important than the treatment of infectious diseases.
Great importance is attached to the education of cleanliness in people.
Ordinary hand washing after visiting the restroom, doing dirty work, before eating can already protect against many intestinal infections.
In addition, the source of infection can be not only public places, but also money, handrails in transport, the surface of counters and much more.
Purchased fruits and vegetables can be a source of helminths and other dangerous microbes, so they must be thoroughly washed out before use.
Infectious carriers are cockroaches and rodents, for the fight against which the industry produces a variety of means by which it is necessary to treat the places of their accumulation and spread.
Mosquitoes and ticks cannot be discounted. These insects are especially dangerous, as they carry not only encephalitis and malaria, but also AIDS along with the blood of an infected person.
To protect against ticks and mosquitoes, there are many creams and aerosols to apply to clothing, as well as fumigators and repellents.


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