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.

Cat Scratch Disease

Cat scratch disease is an acute zoonotic infection caused by the gram-negative bacterium Bartonella henselae, which enters the human body with bites or scratches of cats. A typical form occurs with primary affect in the form of papular-pustular rashes, regional lymphadenitis, fever, hepatosplenomegaly. There may be atypical forms of the disease – ocular, anginal, abdominal,…

Brill-Zinsser Disease

Brill-Zinsser disease is a relapse of epidemic typhus, which preserves the clinical manifestations of the primary disease, but proceeds mainly in a mild form. A characteristic clinical symptom is an abundant roseolous-petechial rash on the skin, mucous membranes. Systemic manifestations are fever, changes in consciousness, a tendency to tachycardia and hypotension. Confirmatory diagnostic methods include…

Middle East Respiratory Syndrome

Middle east respiratory syndrome is an acute, highly lethal infectious disease caused by an RNA–containing beta-coronavirus. The pathognomonic symptoms of infection are a predominant lesion of the respiratory tract with a high probability of developing respiratory distress syndrome in adults. Clinically, the disease is manifested by fever, shortness of breath, cough, hemoptysis. Diagnosis of pathology…

Blastomycosis

Blastomycosis is a disease from the group of systemic mycoses that occurs with primary lung damage and hematogenous dissemination of fungal infection into internal organs, bones and skin. Disease can occur in various forms: pulmonary (bronchopneumonia), skin (rash, skin ulcers, subcutaneous abscesses), bone (osteomyelitis, arthritis), genitourinary (prostatitis, epididymitis), etc. The diagnosis is confirmed by isolating…

Rabies in Humans

Rabies is an infectious zoonosis of viral etiology, characterized by predominant severe damage to the central nervous system, threatening death. A person becomes infected with rabies when bitten by animals. Spreading along the nerve fibers, the rabies virus initially increases their excitability, and then causes the development of paralysis. Penetrating into the tissues of the…

Bacillary Angiomatosis

Bacillary angiomatosis is a chronic infectious disease caused by bartonella bacteria. The disease is attributed to opportunistic invasions, most often found among HIV-infected people in the AIDS stage. The main manifestations are skin changes, fever, lymphadenopathy, and in some cases, lesions of internal organs. Diagnostics is based on microscopy, PCR examination of histological preparations and…

Bartonellosis

Bartonellosis is a group of diseases caused by bacteria from the genus Bartonella, occurring with a predominant lesion of endothelial cells and erythrocytes. Clinical manifestations can be different: from mild and local (rash, lymphadenopathy, conjunctivitis) to common systemic disorders (fever, anemia, septic bacteremia, endocarditis, meningitis, myelitis). Diagnosis of bartonellosis is based on the detection of…

Balantidiasis

Balantidiasis is a protozoal intestinal infection caused by ciliated infusoria – balantidias. Clinical manifestations  are a reflection of inflammatory and ulcerative processes in the large intestine, and are characterized by abdominal pain, tenesmus, frequent loose stools with an admixture of blood and pus, weight loss, intoxication syndrome. For the diagnosis, clinical and epidemiological data, the…

Aflatoxicosis

Aflatoxicosis is acute poisoning or chronic intoxication that develops due to the use of products containing mycotoxins of Aspergillus fungi. Large doses of aflatoxins cause acute liver failure, coagulopathy, seizures; prolonged use of mycotoxins in smaller doses can provoke developmental delay in children, congenital anomalies in offspring, cirrhosis and liver cancer. The etiological diagnosis is…

Aspergillosis

Aspergillosis is a mycosis caused by various types of mold fungi of the genus Aspergillus and occurring with chronic toxic-allergic manifestations. With aspergillosis, the bronchopulmonary system and paranasal sinuses are mainly affected; less often – the skin, visual system, central nervous system, etc. Patients with low immune reactivity may develop disseminated aspergillosis. The leading role…