Epidemiological analysis

Epidemiological analysis is the study of the regularities of the epidemic process (often on a limited territory for a certain period of time) through the use of specific methods and techniques. The epidemiological analysis related to identification of driving forces (reasons and factors and the peculiarities of the spread of infectious diseases among the population in a particular place and time. The purpose of epidemiological analysis is to develop a sound plan for effective sanitation and anti-epidemic measures aimed at the struggle for a sharp reduction and elimination of infectious diseases. As a result of epidemiological analysis are compiled epidemiological (so-called opportunistic) reviews covering quantitative characteristic of the epidemic process (number of cases and seasonality identified during the analyzed period, expressed in intensive and extensive indexes), the distribution of cases in different sex, age and professional groups of population with the sanitary-hygienic conditions of their life, nutrition, water supply, Sewerage, etc.
Matching results of these materials with data for the similar previous period enables to assess the effectiveness of measures taken to combat considered infectious disease and to identify trends in its epidemic manifestation in the future, in other words, for making informed enough epidemiological forecast. Based on the latest and formed a comprehensive plan for the conduct of sanitary, prophylactic and anti-epidemic measures in the nearest during the analyzed period of time.
As is known, the main link of the epidemic process in any infectious disease is the focus of the infectious diseases (see the Hearth of the epidemic). Therefore, study of regularities of the epidemic process (epidemiological analysis) is impossible without a compilation of material epidemiological survey (exploration) of these foci, the purpose of which is the deciphering of the reasons of their occurrence and formation (see Epidemiologic study). Priority epidemiological survey of middle of an infectious disease is a choice and carrying out effective measures aimed at its localization and liquidation (except a possible source of infection - infected food, contaminated water, hospitalization sick, disinfection, disinsection, surveillance of contacts, use of antibiotics, bacteriophage, the introduction of gamma globulin , and so on). The more distant goal of epidemiological survey, based on detection of specific links between individual sites of relevant infectious diseases, is the establishment and neutralization pathways its agents among the population. Epidemiological survey of the center, regardless of the number of cases (individual cases or a one-stage disease groups) requires a high efficiency in the work of epidemiologists.
When conducting epidemiological analysis along with the materials of epidemiological surveys and data on the number of cases at different times of the year, their distribution by sex, age, profession with the sanitary-hygienic and sanitary-and-communal living conditions and life are involved, and other materials. So, considered the state of immunological structure of the population (according to the implementation of the plan of preventive vaccination, setting immune and allergic reactions, selective serological studies, and so on). In the case of zoonoses - contact patients with Pets and wildlife, the degree of availability of public final Fund for admission infectious patients, the level and quality of laboratory diagnostics, health facilities and locations for collecting, processing, transportation and sale of food products and catering etc.
Clarifying these and other issues should be unified, because only in this case the results of epidemiological analysis can be summarized (generalized) at the level of oblast, region, Autonomous Republic of the Union Republic and, finally, the country as a whole. Therefore, the drafting of the epidemiological survey carried out by a special form with mandatory filling of the Fund analytical tables.
Instructions and methodological materials for conducting epidemiological analysis constantly improved and periodically reissued by the Ministry of health of the USSR.
The most significant when conducting epidemiological analysis is the assessment conducted in the fight against infectious diseases preventive and control activities and find ways to maximize their effectiveness in a specific territory.
When collecting the materials needed for epidemiological analysis, the method of examination centers of infectious diseases, as well as statistical, laboratory (microbiological, virological, immuno-Allergology, parasitological, sanitary-hygienic, epidemiological and entomological techniques. In recent years, when conducting epidemiological analysis are increasingly used sociological and mathematical methods.
For a full epidemiological analysis requires knowledge of relevant data on areas located nearby. This is the information-reference material about infectious diseases that are regularly published by the ministries of health of the USSR and Union republics.

Epidemiological analysis is a method of studying the peculiarities of the epidemic process in order to clarify the causes contributing to the spread of infectious diseases in the area, and the development of the plan of measures for their prevention and elimination. There are currently, or operational, and retrospective epidemiological analysis.
The current, or operational, epidemiological analysis - daily analysis of communicable diseases in the area, its causes, epidemiological patterns of distribution. It is needed for decision-making on necessary anti-epidemic and preventive measures: immediately (depending on the sanitary and epidemiological service and other institutions of the health authorities) or later (requiring the decisions of the local Executive committees of the Soviets of working people's deputies). In cases of epidemic outbreaks or epidemics of infectious diseases operational epidemiological analysis is particularly great importance and urgency in view of the urgent need to draw conclusions about the nature and the leading parts of the epidemic process for the organization of anti-epidemic measures.
Retrospective epidemiological analysis - analysis of the same data for the last period of time (a year, half-year, quarter, the period of the last outbreak or epidemic). It is done with the purpose of scientific evaluation of data on the incidence of infectious diseases, held epidemic outbreaks and epidemics, the identification of new epidemiological patterns of disease, assessment carried out anti-epidemic and preventive measures and development of proposals for inclusion in the work plan for the next period.
Materials for epidemiological analysis are: emergency notifications of infectious disease registration journal of infectious diseases, maps epidemiological surveys; information about diseases in children's institutions and industrial enterprises, the carriers of infection; about the activity of infectious hospitals and offices at polyclinics; on the study of epidemic outbreaks and epidemics, as well as seasonal increases in morbidity in the territory; on the work of the laboratories of sanitary-epidemiological stations; on natural foci of vector-borne diseases if they are present on this territory; about the sanitary condition of settlements; about the state of public utilities (cleaning, water and other local peculiarities city, village, district, having epidemiological significance. All materials are grouped into separate infectious forms, and with epidemiological analysis takes into account epidemiological features peculiar to each of infectious disease. For the results of epidemiological analysis of a great importance is the quality of the analyzed materials, it is necessary to take care in their daily work.
When epidemiological analysis of the causes of infectious diseases focuses on the most common diseases that cause economic damage to the production and human health. An exception may represent isolated cases of especially dangerous infections, which appeared in the area requiring urgent study, analysis and emergency anti-epidemic measures.
Analysis of emerging epidemic foci (see) infection on the basis of the data of the epidemiological survey (see) and the address of the account of patients makes it possible to establish the nature of the sources of infection, time of occurrence, the number of cases in each hearth, the movement of foci in time, the relationship homogeneous foci among themselves; role in the transmission of household contact, food, water, respiratory and other factors; the role of convalescents and bakterionositelej in the emergence of epidemic foci; location epidemic foci on the territory; the age structure of the patients and their professional identity and other
Emphasize epidemic foci that arose in the conditions of production (i.e., associated with health conditions at work), in children's institutions (schools, boarding schools, day nurseries, kindergartens, children's homes etc), the hospital of infectious diseases patients and medical staff.
Analysis of the data listed determines the possibility valid conclusions about the characteristics of the epidemic process in the infection (the leading factor of transmission of the infection, the most affected age and professional groups, the most affected area, and so on).
Clinical data, information on bacteriological, virological and other laboratory studies help to clarify a number of diseases, especially their clinical course, mortality, to determine microbial pathogens description of the disease.
Well verified information about the immune gap among susceptible populations, especially against polio, diphtheria, pertussis, and also data on the results of mass Allergy testing and serological studies allow us to foresee the possibilities of the further dynamics of the disease and the need for additional preventive measures.
Identify the most affected areas areas (city districts, streets, homes, group homes, rural district, village, etc.,) gives grounds to search for the link increased morbidity with local conditions of life, food, water, sanitary conditions of production and other features of this site. Intestinal infections it is important to know what is for the local population have nearest open water bodies; whether the population of these bodies of water for drinking, bathing and other domestic purposes, what is the sanitary condition of water bodies, cleanliness and water quality, pollution sources.
Comparison of morbidity in the affected areas for the same period of time in several years may indicate many years of trouble district, plot for this infection, which should be followed by a detailed examination of the causes of ill-being. If the area, the site became epidemically dysfunctional for the first time in many years, so there were new conditions determining the increased incidence of - the arrival of new people from disadvantaged by infection areas, the emergence bakterionositelej, damage to water supply network, a breakthrough sewage and other reasons, require intervention epidemiological services.
An analysis of the age distribution of incidence is one of the important elements of epidemiological analysis. The most accurate part of each age group of the population in the overall incidence of the disease is determined in intensive indicators, i.e., 1,000, 10,000 people each given age. Extensive indicators determine the proportion of each age group of the population in percentage in total for all ages incidence of this infectious disease. Extensive indicators can be calculated only for relatively short periods of time (several weeks, one or two months), because only in this case, you can ignore the changing population, conditionally accepting it unchanged. Standardization intensive morbidity in age groups of the population and their comparison with standardized data for the same period of the previous years allows to judge about the typical characteristics of an elevated incidence in different age group, or to talk about the singularity of a higher incidence of any age.

The sharp increase in intestinal infectious diseases among adults often associated with food or water factors of transmission; later there are cases among children. The increased incidence of so-called children's infections points to the shortcomings in the conduct of specific prophylaxis against diphtheria, whooping cough, polio, and on the emergence of infectious hepatitis is connected with the defects of the sanitary maintenance of schools (latrines, bars), kindergartens (toys, dishes, pots), with poor sanitation open reservoirs where bathe children of school and preschool age, with defect prevention
hepatitis and unsatisfactory prevention of gamma globulin.
In each case epidemiological analysis helps to identify the leading causes of increased morbidity.
Analysis of the spread of diseases among people of certain professions allows you to select groups whose work continuously or intermittently connected with the risk of infection. The former include working sanitation, irrigated fields of sewage waters and sewage disposal (intestinal infection); people dealing with contaminated scrap involved in the collection, processing and waste disposal, etc. may Periodically be subjected to the exposure of workers sistematizirovany and wool-washing factories, processing of tanning raw materials (anthrax), working piecemealing shops (ornithosis) and other Systematic conducting of preventive measures on production significantly reduces the risk of diseases.
An increased incidence of working can be connected with the defects of the sanitary condition of the company, drinking water supply, public catering, consumer services, public latrines, and possibly with the penetration kitchens bakterionositelej, with the lack of a specific disease prevention and health education work.
If the list of infected workers to be indicating specialty (mechanic, Turner, molder, caster, and so on) and place of work (shop, area, team and other), it becomes extremely useful for epidemiological analysis of the causes of diseases and carrying out anti-epidemic and preventive measures. Often the disease is spread generalized categories: workers, employees, workers of public catering enterprises and food industry, public utilities, child care, Housewives, pensioners, etc. Such distribution of cases by generalized categories of little use, especially for operational and epidemiological analysis.
In cases of epidemic outbreaks or epidemics of infectious diseases is very important for further analysis to install and carefully study the first cases of the disease, especially when rare in the area of disease, allowing more likely to identify sources of infection than the subsequent analysis of the cases when effect variety of factors mass of transmission. Considering that often the first cases of such diseases are not recognized, it is useful in places of initial emergence of them to study the history of the disease in some patients suspected on the basis of the clinical picture of the disease, and, if necessary, to produce retrospective serological studies. Epidemic outbreaks normal local infectious diseases begin with more or less sharp increase in their numbers. But in this case, particularly thorough study of the causes of diseases in the beginning of the rise in the incidence facilitates the identification of the primary sources of infection, have not disguised by the effect of other factors of transmission. For the convenience of operational and epidemiological analysis, in addition to daily journal recording of patients, it is recommended to use the summaries of morbidity in five days, for all time of epidemic outbreaks or epidemics.
The analysis of the nature of the ascent of diseases - from sporadic cases, foci diseases, slow growth, more or less limited number of cases, the distribution area and duration of outbreaks of disease) epidemic outbreaks to blast disease with simultaneous coverage of a large number of people in large areas is likely to judge the leading factors of transmission.
Gradual increase in the number of diseases until it reaches a maximum, followed more or less slow their decline is most often characterized by seasonal epidemics of diseases, which are essentially the annual epidemics. These epidemics are among the few that can be easily foreseen.
When retrospective epidemiological analysis of incidence (each infectious disease) is considered as a whole for the analyzed period of time in monthly distribution during the year in the percentage of the amount for the year in absolute numbers. Received standardized results compare with standardized data for previous years by determining how typical the observed rise of disease (seasonal) or he is atypical. In the latter case, the reasons for the observed atypical rise in the incidence establish methods of epidemiological analysis.
Study the distribution of diseases between cities and rural areas; impact on the dynamics of diseases of mass immunization conducted during the reporting period; the efficiency of bacteriological laboratories for diagnosis of diseases, the identification of infections among patients, workers of food establishments, factories of food products, children's institutions, enterprises of trade in food and other; completeness of bacteriological and sanitary control of water supply and so on, All these data are considered in view of the impact of events held on the dynamics of diseases. From this point of view, evaluate and other anti-epidemic and preventive measures, and the factors of the social order, which had a particular impact on the intensity of epidemic process.
Eventually epidemiological analysis epidemiologist should be as complete as possible a picture of all drivers of the epidemic process (every infectious form) and develop a plan of concrete measures for the next period of work. In some cases the results of epidemiological analysis allow to make a well-reasoned epidemiological forecast.
Full epidemiological analysis may lead to the identification of new patterns of epidemic diseases original organizational forms and methods of anti-epidemic work and thus to enrich epidemiological practice and science.