Geography, Medical

a science that studies the geographic distribution of diseases and pathological states of humans, the reasons for that distribution, and the influence of the geographic environment on the health of a population. Medical geography studies the natural and social factors that condition the varied frequency and course that are characteristic of certain diseases among populations in different localities. The geographic distribution of diseases is conditioned by natural factors, including climate and the presence or absence of certain chemical elements in the water and soil and consequently in the food products. Social factors such as material conditions of life, cultural level of the population, and traditional diet also play a decisive role in the geography of certain diseases of humans (nosogeography). Also important in determining the geographic distribution of diseases are factors that act within the human body and arise in the process of its development. Medical geography is closely connected with epidemiology, microbiology, hygiene, and pathology, as well as physical and economic geography and especially landscape geography.

It has long been noted that many diseases of humans are found only in certain definite regions of the globe: for example, yellow fever occurs in countries of South America and Africa, leishmaniasis appears only in hot countries, particularly in Middle Asia and Transcaucasia, and cholera occurs in India and her closest neighbors in Asia. Even diseases that are universally distributed are found more frequently in some regions than in others.

Scientific research in medical geography appeared as early as the 18th century. In Russia the field is associated with the names of O. Gun, A. P. Vladimirskii, and la. A. Chistovich.

Significant contributions to the development of medical geography were made by the work of the English scientists S. Hennen and H. Marchall and the French scientist C. Boudin. In 1915 the Russian epidemiologist N. A. Gaiskii for the first time juxtaposed nidi of plague and landscape subdivisions of dry land.

The founders of medical geography as an independent science in the USSR were D. K. Zabolotnyi and E. N. Pavlovskii, who proposed the methodological foundations of contemporary medicogeographic research. In the 1950’s and 1960’s A. A. Shoshin, E. I. Ignat’ev, and A. G. Voronov made great contributions to the study of medical geography. In the mid-20th century Soviet scientists, including A. P. Avtsyn, G. M. Danishevskii, and A. V. Chaklin, began intensive research on the distribution of tumorous diseases (chiefly cancer), cardiovascular diseases, and other diseases in relation to climatic and geographic conditions. This trend evolved as an independent branch of medicine and was called geographic pathology.

Research on epidemiologic geography, or the geography of infectious diseases, is an important part of medical geography. Based on a study of the geographic distribution of many infectious and parasitic diseases that developed during evolution, E. N. Pavlovskii created the concept of the natural endemicity of so-called transmissive diseases. Epidemiologic geography studies the areas of distribution of certain infectious diseases in their historic and present state. Establishing the confinement of natural nidi of a given disease to a definite geographic landscape makes it possible to suggest the origin in that region of a certain infection.

In clarifying the mechanism of the origin of a given infectious disease in a definite region, the preparation of medico-geographic maps plays an important role. The characteristics of areas of distribution and their boundaries have been carefully studied for diseases spread by animals—the sources of infection—and arthropods, which inhabit definite landscapes. For example, plague is found in steppe, semidesert, and desert zones, which are inhabited by susliks, marmots, sand rats, and other natural carriers of plague. Russian tick-borne encephalitis infections occur in the forest zone, which is inhabited by ixodid ticks, the carriers of the virus that causes this disease. The dimensions of the areas of distribution and the character of their boundaries depend on various natural, social, and economic factors, careful study of which is necessary for successful control and prevention of infectious diseases.

Also studied are complexes of infectious diseases (epidemiologic complexes) that are typical of given regions. Characteristics of the distribution of infectious diseases inherent in various natural regions are elucidated. This branch of medical geography is called regional epidemiology. Research in this field clarifies the reasons for the existence of the epidemiologic complexes that characterize a given territory. The reasons may be extremely varied and may include work and living conditions, migration processes, demographic factors, type of landscape, and animal species and their ectoparasites.

Works in medical geography have great practical significance, since they make possible the elaboration of medicogeographic prognoses for sparsely populated territories that are not yet economically well integrated. Medicogeographic work also makes it possible to predict the possible character of the influence on the health and morbidity of the population of new complexes that arise as a result of man’s transformation of nature.

The Commission on Medical Geography of the International Geographical Union is occupied with the organization of medicogeographic research abroad. In the USSR the Commission on Medical Geography of the Geographic Society of the USSR (Leningrad) was founded on the initiative of E. N. Pavlovskii. The same type of commission also exists at the Moscow branch of the society. Laboratories of medical geography are operating at the Geographic Institute of Siberia and the Far East (Irkutsk) and at Moscow University. Problems of medical geography are treated in various geographic and medical anthologies as well as in abstracts and specialized geographic and medical journals.