Microbiology, virology, parasitology, infectious diseases, hygiene sciences and other disciplines study the problem of infectious diseases in various aspects. However, only epidemiology investigates the conditions under which infectious diseases can exist and spread and equips the population with methods to protect against them.
Epidemiology can therefore be defined as the science of the patterns underlying the emergence and spread of infectious diseases in the human community and as measures to prevent and control them.
The earlier definition of epidemiology as an epidemic science was inspired by the widespread and often catastrophic spread of many infectious diseases and gradually lost its original meaning. It is all the more unacceptable to define epidemiology as a science of any diseases that are spreading among the population.
Undoubtedly, the method of epidemiology is suitable for the study of hypertension,mental illness, alcoholism and other diseases, but this is another matter. At the same time, the main tasks of epidemiology remain unshakable, and it as a science does not lose its clear order.
It is impossible to agree with the definition of epidemiology as a science on the ecology of infectious diseases in human society, as in this case the most important elements of the doctrine about infection (the mechanism of the pathogen’s transition from the body to the body, susceptibility, immunity), natural and social conditions that affect the course of infectious and epidemic processes and epidemiological practice remain out of sight.
Epidemiology deals with a large number of infectious diseases. The list of them as science develops and scientific research expands continues to grow. Since, for a number of reasons, the spread and course of various infectious diseases, despite significant differences, have similar traits, not only is it possible, but also most rationally, many issues that are of a common nature in theory and practice, to solve out of touch with the specific features of a particular disease. This is done by general epidemiology.
The content of private epidemiology is the study of the specifics of the spread of individual infectious diseases and the development of the most rational preventive and anti-epidemic measures on this basis.
Therefore, epidemiological theory and epidemiological practice are mutually and inextricably linked to each other and they should be considered in unity as two sides of a single science.
History of epidemiology
Epidemiology originated from observations of the spread of infectious diseases and practical activities used by people in the fight against them since ancient times.
In the era of ancient formations, man was helpless in the fight against infectious diseases. The reason for them, especially during the primitive-general system, people saw in action evil otherworldly forces. From here there were still some more preserved to this day in the changed form of the methods of appeasement and expulsion of evil spirits. In parallel with measures based on the demonic notion of the nature of infectious diseases, empirical methods of control were used to some extent rational, such as withdrawal from disadvantaged areas.
Empirical methods of prevention and control of infectious diseases have developed significantly during the slave-owning system. Thus, in Egypt to fight fleas in the room used ash, to scare away rodents used tangles of wool ichnemeone (predatory mammal), examined animals, branding sacrificial meat.
In Assyria and Babylon, the link between epidemics and epizootics was observed between 2000 and 3000 BC. In the fight against epidemics practiced removal of patients outside the city line, burning of things sick and dead, extermination of rabid animals, planned routes of care from the area, disadvantaged in disease, and determined the order of care of the population, applied closure of borders. In China, valiolation was used to prevent smallpox more than 3,000 years ago.
During the epizootics it was considered appropriate to leave the inhabited areas. To protect against insects used nets, alkaline, sesame oil.
In ancient India in Vedas (collection of hymns and prayers) there were indications of the link between plague in humans with epizootics among rats, rabies – with animal bites. The lepers were removed from the settlement, and the population was evacuated when the plague appeared. The concept of infectious diseases in ancient Greece and ancient Rome has expanded even further.
Hippocrates (460-377 BC) rejected the idea of their divine origin. Thucydides (460-400 BC) made an ingenious assumption about the nature of the pathogen. In the fight against infectious diseases in Greece resorted to disinfection, the corpses of the dead burned, there was control over the removal of sewage and the quality of food. In Rome, the burial of the dead within the city limits was prohibited and other public events (cleaning of the territory, water supply) were regulated by law.
Of course, even the unquestionable preventive measures used in the distant past could not have ruled out the spread of infectious diseases. Of the largest epidemics deserve to mention the “plague” of Thucydides, the “sea ulcer” antonina and especially the “plague” of Justinian, which covered the vast expanses.
In the era of feudalism, the rudiments of personal and social prevention of the ancient world were lost. Persistent epidemics, and especially the plague pandemic in the 14th century, which remained in the memory of all peoples called “black death”, encouraged doctors to develop preventive measures.
In 1374, for the first time in Venice was quarantined. There was a ban on lepers to visit churches, bakeries, mills, use wells. At the same time, the emergence of hospitals and shelters for lepers in Europe. In the next century, Fracastoro (1478-1553) substantiated the doctrine of contgia and pointed to the danger of the patient to others.
In Russia, in the era of feudalism, our ancestors went their own way in using methods of prevention. Already in the 11th century it was recognized necessary to isolate the sick, burial in special cemeteries of corpses of dead from squalic diseases. Since 1352, fires have been lit on the roads during plague epidemics. This measure was a kind of precursor to quarantine. In 1552, guard posts were put up for the first time in Moscow to prevent the adhesive from entering Moscow. They were widely used in the future.
Internal quarantine began to be applied around 1510-1519. The house was sealed in the event of the death of the residents, and near the houses where there were sick, put up posts. Since the 16th century, much attention has been paid to the dissemination of infectious diseases in neighbouring countries. There are also indications of disinfection activities in the annals.
The initial period of the development of capitalism was accompanied by endless wars, against which infectious diseases became widespread, affecting the working masses, who were in dire socio-economic conditions. At the same time, the “industrial revolution” gave a powerful impetus to the development of science and technology.
Influenced by the works of Sidenham (1624-1689), doctors returned to the path of objective study of infectious diseases. The eighteenth century was marked by the discovery of Jenner (1749-1823) a method of vaccination against smallpox and classical studies of D. S. Samoilovich (1744-1805) on epidemiology and measures to combat the plague. A significant step at that time in Russia was made to improve the system of quarantine (road outposts, banning ships with patients on board, enter the harbor, delay couriers arriving from plague-deprived areas), as well as to organize anti-epidemic measures (creation of commissions, issuance of regulations) and elimination of the consequences of epidemics (burial of corpses, cleaning and disinfection of premises).
At the end of the 19th century and beyond, thanks to the success of microbiology, a solid scientific basis was brought under the most important epidemiological presentation, and new vast horizons for objective research and practical activity were opened before epidemiology.
Brilliant pages in the history of microbiology and epidemiology entered L. Pasteur (1822-1895) and R. Koch (1843-1910). Russian scientists also made a great contribution. The doctrine of susceptibility and immunity is associated with the name of I. I. Mechnikov (1845-1916). D.I. Ivanovsky (1864-1920) has the honor of discovering viruses. S. P. Botkin (1832-1884) laid the foundations of the teaching on infectious jaundice. G. N. Minh (1836-1896) and O. O. Mochutkovsky (1845-1903) as a result of heroic experiments of self-inscitation (the first – the blood of the patient with typhoid, the second – typhus) showed that the pathogens of these diseases are in the blood. They expressed the opinion about the transmission of typhoid and recurrent typhoids with blood-sucking arthropods. P. F. Borovsky (1863-1932) was the first to discover the pathogen of skin leishmaniasis. V.K. High (1854-1912) discovered the ability of endothelial and fixed cells to capture microbes injected into the bloodstream; independently of Wexelbaum, he established the microbial etiology of cerebrospinal meningitis and was the first in Russia to immunize against typhoid. The development of siaphology of diphtheria and the justification of streptococcal etiology of scarlet fever are associated with the name of G. N. Gabrichevsky (1860-1912). I.G. Savchenko (1862-1932) applied enteral immunization against cholera. I. A. Deminsky (1864-1912) was the first to prove the role of small gophers in the epidemiology of the plague. D.K. Sabletny (1866-1929), who is the founder of domestic epidemiology, conducted classical studies on epidemiology of plague, cholera and other diseases. Confident in the zoonous nature of the plague, he brilliantly proved this by singling out the pathogen from the tarbagan in 1911. N. N. Claudenitsky (1876-1938) first described the plague of a camel. L. A. Tarasevich (1863-1927) has merit in the organization of vaccines and serum production. E. I. Marcinovsky (1874-1934) was one of the organizers of the anti-malarial service in our country. E. N. Pavlovsky’s research (1884-1965) on natural focal points gained worldwide fame. K.I. Scriabin (born 1879) created the doctrine of devastation. It is necessary to point to the research of V.A. Bashenin (born 1882) on the problem of leptospirosis and L. V. Gromashevsky (born in 1887) – in the development of a doctrine on the mechanism of transmission of pathogens.
A. Y. Alymov, A.N. Sysin, N.F. Gamalei, I. I. Yelkin, P.F. Sdrodovsky, N.N. Shchukov-Vereznikov, I. I. Rogozin and other domestic researchers have done a lot for the development of the theory and practice of epidemiology.