An epidemic is said when the number of cases of a disease is significantly higher than the norm. These are mainly infectious diseases: plague, smallpox, scarlet fever, typhus, diphtheria, cholera, measles, flu. The branch of medicine that studies epidemics, their occurrence and methods of dealing with them is called epidemiology.
The nature of epidemics is usually acquired by those diseases that are quickly and easily transmitted from person to person. The main ways of spreading infectious diseases: - through food, water or household contacts (dysentery, typhoid fever, etc.); - airborne droplets (for example, influenza); - through blood-sucking insects (malaria, typhus); - contact route: through blood and other fluids (AIDS, rabies). There is also such a thing as mental epidemics, that is, the widespread occurrence of certain mental illnesses. This usually occurs on the basis of religious or revolutionary movements. The reasons for their occurrence are superstition, suggestion or self-hypnosis, the desire to follow the leader or just the majority. So a large number of people may experience hallucinations, visions, seizures, bouts of hysteria, bursts of aggression, and suicidal moods. An example is the dances of St. Vitus, the epidemic of which appeared at the end of the XIV century. As for infectious natural diseases, their causes are varied and have not been fully elucidated by scientists. Many factors can influence the occurrence of epidemics, overlapping each other. So, there is a version that the abnormal summer heat leads to the activation of the influenza virus in winter. Scientists have been thinking about the causes of epidemics for a long time. Even in ancient Egypt, the idea of natural disasters as the cause of natural diseases arose. Russian scientist A. L. Chizhevsky created a cosmological theory according to which global processes occurring on Earth (wars, crises, epidemics) obey the cycles of solar activity. Both socio-economic theories (founder - David Ricardo) and ethical and cultural (Albert Schweitzer) were put forward. Epidemics in the history of mankind are mainly problems of cities, since in conditions of a crowded population, contact with the virus is more likely. Add to this poverty and unsanitary conditions, the ideal conditions for an epidemic to emerge. An example of this is Europe in the 14-17 centuries, when sewage was thrown out of the windows directly onto the street. The plague of 1665 claimed the lives of a third of London's population. Scientists suggest that the disease originated in Central Asia, reaching Milan with ship rats. People blamed Jews for their troubles, then witches, or their own sins, until the number of rats and fleas that lived on them fell. Outbreaks of plague have receded - it happened at the end of the 17th century. Now, when sanitary conditions have improved significantly, epidemics are not a thing of the past (flu, AIDS), and until now scientists have not come to a consensus on methods of combating them. Someone hopes for the achievements of medicine, and someone is looking for the roots of the disease in the spiritual crisis of mankind. Problems of a new nature also arose, for example, in highly developed countries, cardiovascular diseases acquired the character of an epidemic.
