What is Scabies?
Scabies is a contagious parasitic skin disease caused by the scabies mite, which is visible to the eye as a whitish, about the size of a poppy seed, dot.
The first descriptions of scabies were made more than 2500 years ago. Scabies is described in the Old Testament and in the writings of Aristotle. In ancient Greece, scabies was attributed to a group of skin diseases united by the term psora. In ancient Rome, scabies was called scabies; this name has been preserved to this day. In medieval treatises, assumptions were made about the parasitic nature of scabies. Reliable evidence of the role of scabies mites in the development of the disease appears only after the creation of an optical microscope. In 1687, Italian physician Giovan Cosimo Bonomo and pharmacist Diacinto Cestoni first described the relationship between scabies mites and typical skin symptoms that develop after infection. It was they who first established that the disease can be caused by a microscopic organism. A complete and reliable description of the etiology and pathogenesis was given in 1844 by the German dermatologist Ferdinand Gebra. This manual was translated into Russian by A. G. Polotebnev in 1876.
There are theories about the wave-like nature of the incidence of scabies with a frequency of 7-30 years. However, these theories are heavily criticized. There is evidence of a cyclical increase in the aggressiveness of scabies mites due to the development of its resistance to a number of scabicides. Also, bursts of morbidity during periods of war, natural disasters, famine and other social phenomena leading to crowding of people are noted.
The incidence of scabies is characterized by seasonality. In Ukraine, this is autumn-winter. The same data was obtained from a 20-year observation in the Israeli army. The seasonality of the disease is partly due to the biological characteristics of the mites themselves, the fecundity of which reaches a maximum in September-December, as well as the fact that cool conditions contribute to better survival of itching in the environment. In addition, cold contributes to crowding and reducing perspiration (later, antimicrobial peptides are secreted, to which scabies are partly sensitive). In countries of West Africa, peak incidence is also noted in cold and dry seasons. In the same places where no pronounced climatic seasonality is observed, the incidence of scabies is evenly distributed throughout the year (Bangladesh, Gambia, Brazil).
Scabies can occur both epidemically and endematically. Sporadic outbreaks are characteristic of industrially developed countries, where the disease is localized mainly in organized groups united by common bedrooms (military barracks, boarding schools, orphanages, dormitories, prisons, medical institutions, etc.) or in asocial groups of society. Teams whose members are united only in the daytime (groups in kindergartens, classes in secondary and higher educational institutions, labor collectives), as a rule, do not represent an epidemiological danger. The overall incidence rate in such countries is low. According to England and Wales from 1994-2003. incidence of 351 cases per 100 thousand people per year in men and 437 in women was noted. In Russia, the annual incidence, judging by the sale of scabicidal drugs in the pharmacy network, exceeds one million cases.
However, in a number of countries, the incidence is much higher and can reach 40-80%. There are especially many patients among the peoples of Sub-Saharan Africa and the natives of Australia and New Zealand, which is probably due to the peculiarities of their immunity and the structure of the stratum corneum.
In general, at the end of the XX century. About 300 million people (5% of the world’s population) suffered from scabies.
In the world, scabies is more affected by young children, which is associated with their lack of immunity to the pathogen and with more frequent direct contacts with the skin of patients. In Ukraine, the situation is somewhat different. The main risk is the youth age group, which, forming only a tenth of the population, takes on up to 25% of the total incidence. The second place is traditionally occupied by school age, the third is pre-school, the fourth is mature. It is significant that with scabies, the distribution of the incidence among social groups is consistent with the age. The highest incidence is among students, lower among schoolchildren and preschoolers. This situation is explained by the characteristics of sexual activity and the development of antipruritic immunity in various age groups.