Natural focality

Natural focality of doctrine, proposed and justified by academician E. N. Pavlovsky for some infectious diseases of humans (the so-called vector-borne diseases). The characteristic feature of this group of diseases is that they are natural reservoirs of pathogens among wild animals (mainly rodents and birds, among which are constantly epidemic. The spread of the disease occurs through blood-sucking arthropods. So, ticks infected from sick animals, attacking healthy, transmit the infection. Thus, the causative agent of the disease circulating in nature chain: pet - carrier - animal.
Typical epidemiological feature of diseases with natural focality is strongly marked seasonality of diseases, because of the biology of animal keepers of infection in nature or vectors.
Among the natural foci diseases of humans, on the theory of E. N. Pavlovsk include diseases such as plague (see), tularemia (see), tick-borne Japanese encephalitis (see), rabies (see), ornitz (see), toxoplasmosis (see), leptospirosis (see), cutaneous leishmaniasis (see) zoonotic type, tick-borne relapsing fever (see relapsing fever), some worms (see, for example, opistorhoz (see), trichinosis (see) and other
Pockets of vector-borne diseases are associated with a specific geographical landscapes and occupy a specific territory. So, zoonotic cutaneous leishmaniasis type is common in many areas of Turkmenistan, Uzbekistan and Tajikistan. The carriers of activators in the centers are mainly large gerbils, and carriers - mosquitoes (see)living in their burrows. Contracted on the gerbils, mosquitoes can then transfer Leishmania people. Main foci of tick-borne encephalitis are in the form of a tape on the large territory of the USSR (from the Far East to the Western borders of the USSR), mainly pine and fir forests. The main value in circulation tick-borne encephalitis virus acquire the red forest voles and shrews shrew, and transmit them ixodid ticks. In the natural home can be the agents of several diseases, as well as different kinds susceptible to the diseases of animals.
Landscape preferences historically biocenosis of natural focality of permits (on the basis of the developed principles typing natural foci diseases person) to make predictions about the possible existence in a specific area of one or another infection. All this creates the opportunity to recommend the most efficient prevention and promotion activities. Measures against natural focality composed of a set of activities which can be divided into two groups.
The first of them include ways of protection for people living or working temporarily in the centers one disease or another. This is the vaccination of people (tularemia, cutaneous leishmaniasis, tick-borne encephalitis, and some others) and their protection from insects and mites - the wearing of protective clothing, the use of repellents (see), polaryzacja (see).
The second group includes measures on eradication of the epidemic and clean up of certain natural foci. This problem is large and difficult. Solution it may be different in different areas in relation to various diseases. It is necessary to conduct a thorough analysis of the spread of this disease, identification of carriers and vectors, studying their biology and so on Measures of struggle can emerge from the economic development of virgin and fallow lands, taiga on the basis of high agriculture forest management, combating rodent pests (see Deratization) and vector (see pest control). Each of these activities in turn divided into a number of techniques that depend on the many features of the disease, carriers, carriers, commercial plans and other
Cm. also Carriers.


Natural focality - a feature of some diseases, namely, that they are evolutionary in nature arisen centers, the existence of which is consistent with the transition of the pathogen of a disease from one animal to another, usually through the mediation of blood-sucking invertebrates (mites and insects). Natural focal territorially connected with biotopes geographical landscapes and provides historical biocenoses (see).
The doctrine of natural focality of human disease was first described in 1938, E. N. Pavlovsky.
It is closely connected with the development of new lands. There exist in nature independently of the individual foci of diseases typical of wild vertebrate animals. The origin of such diseases refers to a distant past, when the Earth was already a rich world of animals, but still there was no man. The usual components of the natural focus are: disease, blood-sucking insects and mites, their proximately (owners) - wild mammals and birds. Among the blood-sucking arthropods, and among them proximately many species are able to perceive, long-store and disperse in the nature of the pathogen. Arthropods transfer of the pathogen from the sick animal is healthy, and you can type it into the body during krovotechenie. To natural focal diseases include encephalitis, Japanese encephalitis (see), tularemia (see), plague (see), leishmaniasis (see), tick-borne relapsing fever (cm), some ricketsiosis (see), leptospirosis (see), toxoplasmosis (see) and other Natural focal peculiar to the helminthiasis (see), some diseases of wild plants, which are infected plants. Established important patterns of diseases with natural focality. This is, first, the importance not only of the landscape, but the terrain in creating the character of natural biocenoses, circulates the pathogen of a disease. Huge flat expanses of steppe, arid, desert-steppe or meadow landscape, especially in the lowlands, are more or less homogeneous flora and fauna, attributable to each landscape separately. Similar living conditions define homogeneous fauna disease vectors and their hosts-proximately. Less difficult in these conditions and the way of circulation of the pathogen.
In conditions of rugged terrain of mountains and foothills there is a greater variety of living conditions, which determines and a richer species composition of followers in natural biocenoses. In such conditions, the disease makes the complex circulation between different animals that provides the widest distribution. So, when Q-fever, tularemia pathogens spread several dozen species of arthropods and equally wide range of proximately - vertebrates.
However, in natural biocenoses true keepers of pathogenic microorganisms - causal agents of many diseases with natural focality (tick encephalitis, tick recurrent fever, tularemia, endemic ricketsiosis, Japanese encephalitis, and other) are different groups of ticks (see): tick-borne encephalitis and rabbit-fever infection (Ixodes ticks, tick-borne return typhoid argatova and so on Many kinds of ticks years preserve the causative agents of some diseases and can transfer them via the eggs to his descendants. Only when the few diseases (leishmaniasis cutaneous and visceral, leptospirosis, toxoplasmosis) main role in preservation of the pathogen play animals.
The nature of the terrain (the presence of different elements of the landscape, notched relief and other) defines the scope of the spread of diseases with natural focality. This is particularly true for vector-borne diseases that are closely associated with the area, i.e. the area of natural distribution of bloodsucking arthropods as a vector of pathogens of these diseases.
In the natural home can be the agents of several diseases, as well as different kinds susceptible to the diseases of animals. These centers are called oligohaline.
Landscape preferences historically biocenoses natural focal diseases makes it possible to make predictions about the possible existence in undeveloped person areas of certain infections. So, meadow landscapes are more characteristic of natural foci of leptospirosis, Japanese encephalitis; steppe - centers ricketsiosis, forest - foci of tick-borne encephalitis, desert and semi-desert foci of leishmaniasis, tick spirohetozah. There may be in various landscapes natural focal biocenoses, including vertebrate animals and their ectoparasites, capable of long-term sustainable circulation of pathogens of several diseases (tularemia and leptospirosis, q-fever and tick-borne encephalitis, tick spirohetozah and leishmaniasis). Usually natural foci of mixed infections characteristic of areas with rugged terrain (foothills and mountain areas, river valleys, the joints of different landscapes).
The principles typing natural foci diseases of humans (tularaemia, plague and other infections). When tularemia distinguish steppe, field, alluvial, meadow-field, foothill-plain and other pockets; when Japanese encephalitis - coastal-marine, alluvial with hayfields and other Typing natural foci infections is of practical importance. In relation to the types of foci for a number of infections can recommend the most efficient prevention and promotion activities.
Much has been done to identify elementary foci infections, i.e. such specific areas of microlandscape that the pathogen is kept indefinitely. For a number of diseases elementary hearth can be one hole or the group Nord. For example, burrows Jackal and Fox can be centers of visceral leishmaniasis, tick return typhoid, cutaneous leishmaniasis, dengue haemorrhagic fever and other Natural foci number of infections may be, and birds ' nests. For example, the colonies of sand Martin - endemic foci ricketsiosis (tick-borne typhus Northern Asia and q-fever), socket-headed Buntings - pockets of Japanese encephalitis.
The importance of the conditions of existence of the foci of each infection separately often leads to uniform preventive measures, at the same time warning the spread of several diseases with natural focality. This applies, for example, to diseases, in which the main Keeper of pathogens are ticks.
The nature of preventive measures depends on the duration of stay of people in disadvantaged areas. At the time of contact of the population with natural foci (excursion, hunting, haymaking, harvesting of berries, mushrooms and other) designate personal prevention measures, limited to the protection from attack bloodsucking insects and ticks - the use of repellents (see), protective clothing, sleeping chambers (see Polaryzacja)from General hygienic regime in line with the recommendations of the nearest medical institution. Long stay in frontier territories (geological survey work, the construction of roads, surveying the terrain, long walks and other) requires, in addition to the listed measures personal prevention, mandatory vaccination against tick-borne encephalitis, tularemia, leptospirosis, cutaneous leishmaniasis. In large buildings (construction of mines for the development of mineral resources, construction of plants, factories, state farms, workers ' settlements and other) in areas with natural foci of those or other diseases requires a radical improvement of the territory, careful choice of the place for the future work of the village in consultation with medical institutions.
Health activities (the destruction of the burrows of rodents, nesting birds, and so on) are dependent on local conditions.