Infectious diseases ("infectio" - infection) - a group of diseases that are caused by the penetration of pathogenic (pathogenic) microorganisms into the body. So that a pathogenic microbe entering the body can cause infectious diseases, it must be able to overcome the resistance of the human body and exert a toxic effect on it. Specialists call these qualities virulence (toxicity). Some pathogens release toxins (endotoxins) during self-destruction (typhoid fever, cholera). Other pathogens of infectious diseases secrete toxins (exotoxins) in the course of their life (diphtheria, tetanus).
Infectious diseases account for 20-40% of the total number of all human diseases. Microbiological and medical disciplines such as urology, venereology, epidemiology, therapy, gynecology, phthisiology, immunology, otolaryngology, virology and, of course, the “infectious diseases” section of the medicine are involved in the study, prevention, diagnosis and treatment of infectious diseases.