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.
Ascariasis is a helminthic disease, the etiological agents of which are roundworms – ascariids that parasitize in the human small intestine. The early phase of ascariasis occurs with the phenomena of general malaise, fever, skin rash, hepatosplenomegaly, lymphadenitis, dry cough. In the chronic phase, the symptoms of gastrointestinal tract damage come to the fore: decreased…
Argentine hemorrhagic fever is a natural focal zoonosis from the group of South American hemorrhagic fevers caused by the RNA-containing Junin virus. The leading clinical manifestations are hemorrhagic syndrome with bleeding of various localization, severe intoxication. Diagnosis is based on the detection of the pathogen itself and specific markers in the blood serum. Etiotropic treatment…
Hookworm is a helminthic invasion caused by parasitization in the human intestine of roundworms (hookworms or necators) belonging to the Ancylostomatidae family. Clinically, hookworm is manifested by papulo-vesicular rash, cough, shortness of breath, impaired appetite, nausea, abdominal pain, diarrhea, iron deficiency anemia. The diagnosis of hookworm is confirmed by the detection of helminth eggs in…
Anisakidosis is a parasitic infectious disease associated with ingestion of roundworm larvae. The main symptoms are disorders of the gastrointestinal tract and allergic reactions of varying severity. Diagnosis of the disease is usually instrumental with visualization of larvae in the mucous membrane; microscopy of vomiting and faeces almost never reveals the pathogen. Treatment includes etiotropic…
Anaerobic infection is an infectious process caused by spore–forming or non-spore-forming microorganisms in conditions favorable for their vital activity. Characteristic clinical signs of anaerobic infection are the predominance of symptoms of endogenous intoxication over local manifestations, the putrefactive nature of the exudate, gas-forming processes in the wound, rapidly progressing tissue necrosis. Anaerobic infection is recognized…
Amoebiasis is a parasitic disease caused by a histolytic amoeba and occurring with intestinal and extra-intestinal manifestations. Intestinal amoebiasis is characterized by copious mucous stools with an admixture of blood, abdominal pain, tenesmus, weight loss, anemia; extra-intestinal – the formation of liver abscess, lungs, brain, etc. The diagnosis of amoebiasis is based on the data…
Alveolar echinococcosis is a parasitic disease caused by the larvae of the tapeworm alveococcus and occurs with the formation of a primary focus in the liver. In the uncomplicated stage, manifestations of alveolar echinococcosis include urticaria, itching, hepatomegaly, heaviness and pain in the right hypochondrium, bitterness in the mouth, belching, nausea. Complications of alveolar echinococcosis…
Alimentary toxic aleukia is a severe food intoxication caused by mycotoxins of fungi of the genus Fusarium. The specific effect of the toxin is the defeat of lymphoid tissue and bone marrow. The main manifestations of the disease are necrotic angina and hemorrhagic syndrome. Diagnosis consists in detecting the pathogen during bacteriological examination of the…
Acariasis is a group of infectious diseases caused by arachnids. Pathognomonic symptoms for invasive pathologies are organ dysfunctions, for external ones – inflammatory phenomena on the skin and appendages. With high sensitization, allergic symptoms come to the fore. Diagnostics is based on the detection of the pathogen in various biological materials, determination of the IgE…
Acanthamoebiasis is a protozoal lesion of the eyes, skin and central nervous system caused by free-living amoebas. The disease occurs in the form conjunctivitis and keratitis, dermatitis or granulomatous encephalitis. Complications can be corneal perforation, the formation of abscesses of internal organs. The diagnosis is established by detecting amoebas and their cysts in lacrimal fluid,…
