Infectious diseases include an extensive group of diseases caused by specific pathogenic (pathogenic) pathogens and transmitted from an infected individual to a healthy one. The peculiarities of infectious diseases are their contagiousness (contagiousness), the ability to mass epidemic spread, the cyclical course and the formation of post-infectious immunity. However, these features are expressed to varying degrees in different diseases.
This type of disease develop as a result of a complex biological process of interaction of a pathogenic microorganism with a susceptible macroorganism under certain conditions. There are several periods in the development of infectious diseases: incubation (latent), prodromal (the period of precursors), the period of development of clinical manifestations, the period of the outcome of the disease. The outcome of the infectious process can develop in several ways: convalescence (recovery), lethality, bacterial carrier, transition to a chronic form.
Infectious diseases account for 20 to 40% of the total structure of human diseases. Many medical and microbiological disciplines are engaged in the study, treatment and prevention of infections: actually infectious diseases, epidemiology, venereology, urology, gynecology, therapy, phthisiology, otolaryngology, immunology, virology, etc.
The number of infectious diseases known to science is constantly increasing and currently has more than 1,200 units. During his life, a person comes into contact with a huge number of microorganisms, but only 1/30000 of this community is capable of causing infectious processes. Viruses, rickettsias, bacteria, fungi have pathogenicity properties.
Depending on the location of the predominant localization of the process and a certain mechanism of transmission, infectious diseases are divided into intestinal (dysentery, cholera, salmonellosis, escherichiosis, paratyphs A and B, typhoid fever, food toxicoinfections); respiratory tract infections (ARVI, influenza, chickenpox, measles, mycoplasma respiratory infection); external integuments (erysipelas, anthrax, scabies); blood infections (HIV infection, malaria, yellow fever, recurrent and typhus); infections with multiple transmission routes (enterovirus infections, infectious mononucleosis).
By the nature of the pathogen, infectious diseases are distinguished: viral (viral hepatitis A, B, D, E and C, influenza, rubella, measles, cytomegalovirus and herpes infections, HIV infection, meningococcal infection, hemorrhagic fevers); bacterial (staphylococcal and streptococcal infection, cholera, salmonellosis, plague, dysentery); protozoal (malaria, trichomoniasis, amoebiasis); mycoses or fungal infections (aspergillosis, candidiasis, epidermophytia, cryptococcosis).
Infectious diseases are divided into anthroponotic and zoonotic. Anthroponoses include infections peculiar exclusively to humans and transmitted from person to person (smallpox, diphtheria, typhoid fever, measles, dysentery, cholera, etc.). Zoonoses are animal diseases that can also infect humans (foot-and-mouth disease, anthrax, rabies, tularemia, plague, listeriosis, leptospirosis, brucellosis).
Diseases caused by pathogens of animal origin – parasites (ticks, insects, protozoa) are called invasive or parasitic.
Among infectious diseases, there is a group of particularly dangerous (quarantine) infections with a high degree of contagion, a tendency to rapid spread, a severe epidemic course and a high risk of death in the shortest possible time from the moment of infection. Plague, smallpox (considered eradicated in the world since 1980), cholera, yellow fever (and similar epidemiology of Marburg fever and Ebola) are classified as particularly dangerous infections by the World Health Organization. Tularemia and anthrax are also classified as particularly dangerous infections in our country.
Treatment of patients with infectious diseases is carried out in specialized hospitals or departments, in mild cases – at home. A prerequisite for the successful treatment of infections is compliance with a strict anti-epidemic regime. The prevention of most infectious diseases is the observance of sanitary and hygienic rules and specific immunization.
The medical directory of diseases posted on the website “Medic Journal” contains a special section – where you can find useful information about the causes, mechanisms of development and clinical manifestations of infections, as well as about modern diagnostic and therapeutic techniques used in this field of medicine.
Cutaneous larva migrans is a group of infectious skin diseases associated with the defeat of helminth larvae. The main symptom is dermatitis in the form of filamentous lines formed when the pathogen moves in the upper layers of the dermis. The rash is accompanied by severe itching, most often the lower extremities are affected. Typical…
Myiasis is a group of diseases caused by parasitization in human tissues and cavities of larvae of some species of flies. The clinical picture of myiasis is determined by the type of pathogen and the place of its parasitization. Intestinal myiasis is manifested by symptoms of enteritis and colitis; ophthalmomiasis – conjunctivitis, iridocyclitis, retinal detachment,…
Human metapneumovirus (hMPV) is a viral disease accompanied by damage to the upper and lower respiratory tract. More often it occurs in the form of acute respiratory infections with hyperemia of the pharynx, runny nose, cough, fever. In children and weakened patients, metapneumovirus causes bronchitis, bronchiolitis, bronchopneumonia. Virological diagnostics includes PCR of a nasopharyngeal smear, ELISA,…
Meningococcal disease is an infectious disease that combines a whole group of diseases that have a variety of clinical manifestations: from nasopharyngitis to meningococcal sepsis and meningitis. What unites them is that they are all caused by meningococci, which are carried by airborne droplets. Meningococcal disease is dangerous, as it is widespread, transient, can cause…
Melioidosis is a bacterial infection caused by Whitmore’s bacillus and occurs with the formation of multiple septic-necrotic foci in internal organs and tissues. The clinical course is characterized by fever with chills, cough with purulent sputum, chest pain, lymphadenitis, vomiting, diarrhea. Typically, the development of purulent-inflammatory processes in various organs (lung abscesses, pleural empyema, arthritis,…
Boutonneuse fever is an acute infectious disease caused by intracellular bacteria rickettsii. The diagnostic triad includes the presence of primary affect, regional lymphadenitis, skin rash. There is also fever, weakness, myalgia, moderate headache, arthralgia, facial hyperemia, less often hepatosplenomegaly. Diagnosis is based on the detection of antibodies to the pathogen and rickettsia itself in the…
Mansonelliasis is a parasitic infectious disease caused by roundworms (nematodes). The most common clinical symptoms are skin rashes, arthritis and lymph outflow disorders. Helminthiasis is also characterized by fever, inflammation of the lymph nodes, and an increase in the size of the liver. The diagnosis of pathology consists in the detection of the pathogen in…
Malaria is a transmissible protozoal infection caused by pathogenic protozoa of the genus Plasmodium and characterized by a paroxysmal, recurrent course. Specific symptoms are repeated attacks of fever, hepatosplenomegaly, anemia. During feverish attacks in malaria patients, the alternating stages of chills, fever and sweat are clearly traced. The diagnosis is confirmed when malarial plasmodium is…
Giardiasis is a protozoal invasion caused by intestinal giardia and occurring with signs of a functional digestive disorder. Gastrointestinal syndrome (nausea, abdominal pain, unstable stools, flatulence) is the leading one in the giardiasis clinic; intoxication, allergic, astheno-neurotic, hepatolienal syndromes may also develop. For laboratory confirmation of giardiasis, microscopic examination of feces and duodenal contents, ELISA,…
Loiasis is a chronic infectious disease caused by roundworms. A characteristic clinical symptom is the formation of a limited edematous area, mainly on the extremities, as well as damage to the mucous membranes, more often conjunctiva. Visceral invasions are less common. Diagnosis of the disease consists in the detection of the pathogen in the blood…
