EPIDEMIOLOGICAL INDEXES

From Big Medical Encyclopedia

EPIDEMIOLOGICAL INDEXES — the indicators used for the analysis and the characteristic of epidemic process and also for assessment of efficiency of anti-epidemic actions.

In the general epidemiology apply the following indexes: contageousness, ochagovost, seasonality, coli-index and many others.

An index of contageousness (see Contageousness) — a share of the persons (as a percentage) who are getting sick in this infectious disease which is clinically expressed to a form from among susceptible to it within the epidemic center for a certain span. This index allows to define emergence of possible number of patients in the center of an infectious disease at the forecasting of development of epidemic process and planning of scale assumed a dignity. - the prof. and anti-epidemic actions.

An index of an ochagovost — the quantitative characteristic of intensity of epidemic process expressed by a median number of patients on one epidemic center. This index characterizes intensity of epidemic process in the center, and also degree of efficiency of the held anti-epidemic events. The high index of an ochagovost is an indicator of high virulence of the activator or a high susceptibility of people to a disease in this center, and also insufficient efficiency of anti-epidemic actions.

An index of seasonality — a quantitative index of seasonal fluctuations of intensity of epidemic process; represents the relation of number of cases of a disease for calendar months with the greatest or with the smallest incidence to all-annual incidence. The high index of seasonality in this month indicates the greatest probability of transfer of activators at this time, napr, activation of arthropod carriers of activators.

Coli-index (index of colibacillus) — the indicator of fecal pollution of objects of the environment expressed by amount of colibacilli in 1 l of the studied liquid or in 1 kg of solid matter (for foodstuff and the soil — in 1 g). This index (see the Coli-index, a coli-index) is used as an indirect indicator of environmental pollution, first of all by waters, causative agents of infectious diseases of intestinal group (dysentery, a typhoid, para-typhus, etc.).

At assessment of effectiveness of anti-epidemic actions apply indexes of efficiency, napr, an index of preventive immunological efficacy — an indicator of ability of a vaccine to protect vaccinated people from clinically expressed disease of the corresponding infectious disease. It represents the relation of number of the diseased in group not vaccinated (control) to number of the diseased in equal group of vaccinated. Apply also indexes of preventive efficiency of serum or gamma globulin, preventive efficiency of fight against a carrier.

AA. and. widely use for the characteristic of prevalence of carriers of causative agents of transmissible diseases (see. Transmissible diseases). In the centers of yellow fever (see) and dengues (see) with their help characterize the number of larvae or an imago of mosquitoes of the sort Aedes, iodrod of Stegomyia, the transferring causative agents of these infections. Such is a house index — .protsent houses from among inspected, near to-rykh in tanks with water there are larvae of mosquitoes. In the centers of leyshma-nioz (see) use an index of abundance of mosquitoes — a median number of the mosquitoes caught by means of a flypaper or a tag for a certain time term. In the centers of plague (see) define a flea index — a median number of fleas of this view on one rodent from total number inspected. The indexes characterizing transmissible diseases use for the choice of methods and establishment of volume of actions for destruction of arthropods — carriers of activators.

During the holding antimalarial actions use a number of the indexes characterizing a prevalence of people by malaria (see). Are most common a splenic index — a share of persons (as a percentage) with palpatorno the defined increase in a spleen among a certain group of the population; the parasite rate — a share of persons (as a percentage), at to-rykh in blood is found a plasmodium of malaria, from total number inspected a certain age group (this index is used also for the characteristic of frequency of a parasitosis at a number of infectious diseases); local index — a total share of persons (as a percentage to total number inspected), at to-rykh are found a malarial plasmodium in blood or palpatorno the defined increase in a spleen or both signs at the same time; the index of the average size of the increased spleen offered by R. Ross — the average size of the size of a spleen at persons of this age group of the population with palpatorno the increased spleen; a splenometrichesky index — the work of an index of the average size of the increased spleen on a splenic index. The listed indexes are higher, the prevalence of malaria in this center or the area is wider. The specified indexes use for assessment and forecasting of epidemic process in this or that area and planning of specific actions for fight against malaria. A number of indexes (a gametocyte-ny, sporozoitny, ootsistny) characterizes separate components of epidemic process or weight of a malarial invasion. Gametotsitny index — a share of persons (as a percentage to number inspected), in blood to-rykh gametocytes of this species of malarial parasites are found. It characterizes prevalence of hectare of meta cytocarriers (sources of activators of an invasion). At a high index actions for identification, treatment and sanitation of gametotsitonositel, protection them from attack of mosquitoes are necessary. The Sporozoitny index — percent of females of mosquitoes of the sort Anopheles, from among caught in the nature, at to-rykh during the opening in sialadens sporozoita are found. The Ootsistny index — percent of females of mosquitoes of the sort Anopheles from among caught in the nature, at to-rykh during the opening oocysts on walls of an average gut are found. These indexes characterize degree of infectiousness by malaria of females of mosquitoes of the sort Anopheles in this area. At a high index measures for destruction of mosquitoes, protection of people against their attack are necessary.

The index of mosquitoes with blood of the person — a share of females of mosquitoes, to-rykh contains in a stomach blood of the person, from total number of the females of the sort Anopheles inspected svezhenapivshikhsya. The index indicates availability in this area of people to attack of mosquitoes on them. At a high index it is necessary to take measures for destruction of mosquitoes and protection of people against their attack.

In addition to specified, there are difficult malyariologichesky indexes differing in big informational content. The index of stability of malaria characterizing number of the stings of the carrier of the causative agent of malaria prevailing in this area received by the inhabitant of the center during average life expectancy of a mosquito belongs to such indexes. This index depends on an indicator of longevity of mosquitoes of this look, an index of mosquitoes with blood of the person and a median number of stings of the mosquitoes received by the person in one day. A. Gabaldon in 1949 entered the difficult indexes of endemicity and an egsh-demichnost of malaria determined by value of splenic indexes in 5 years of overseeing by the center. Indexes of stability, endemicity and epidemichnost of malaria characterize degree of prevalence of this disease in this area; they are used for the choice of methods and scoping of actions for fight against malaria. The inoculation index of Makdoneld — a share of the population (as a percentage) receiving the infecting stings of a lump ra-carrier in one day concerns to group of difficult indexes. He points to availability of people to attack of females of mosquitoes on them and intensity of possible infection with malaria of the population of this area. At a high inoculation index measures for destruction of mosquitoes and protection of people against their attack are necessary.

Bibliography: B e l I to about in In, D., D e -»

t I r e in A. A. and Ivan and and to.* Yu. G, Quality and efficiency prmtp.> .epidemichesky actions, L., 19M; An orba with carriers of diseases and m »\\l> national health care, M., 1974; Г \>about m and-sh e in with to and y - L. Century and In and y N the Dr. and x G. M. Private epidemiology, M., 1947; With in and r at p Page. Statistical methods in programs of elimination of malaria, the lane with English, M., 1967. A. Ya. Lysenko.

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