The theory of the etiological selectivity of the main (primary) routes of transmission and their inequality in different nosological forms of intestinal infections

The article deals with the main scientific propositions of an original epidemiological theory, viz. the theory of the etiological selectivity of the main (primary) routes of transmission and their differences in various nosological forms of enteric infections (the theory of conformity). As proved on the basis of scientific investigations carried out for the period of several years, the role of various routes forming the fecal-oral mechanism of transmission (alimentary, aqueous, household) is highly different. In some enteric infections one of these routes becomes the primary (main) route, while other routes are secondary (additional). The primary route determines the wide spread of the corresponding nosological forms of enteric infections (the theory of conformity) and the preservation of their causative agents in nature as species. The secondary routes are only complementary to the activity of the main route of transmission in some degree. In controlling enteric infections, the measures taken with a view to suppressing the activity of the primary route of transmission are, from the epidemiological standpoint in the close and remote prospects, the cardinal ones, while the measures directed against the secondary routes are only palliative.     

Tendencies in the epidemic process of dysentery in Ryazan

In shigellosis caused by Sh. sonnei and Sh. flexneri the epidemic process was found to have considerable difference in the tendencies and pace of its development. Shigellosis which dominated in the etiological structure at the period following 1966 was dysentery caused by Sh. sonnei; it showed the tendency towards a decrease in morbidity rate. Dysentery caused by Sh. flexneri was second in respect to the frequency of its occurrence after 1966 and showed the tendency towards increase. The simultaneous circulation of Sh. sonnei and Sh. flexneri, the differences in the epidemiology of these types of shigellosis make it imperative that they be studied separately, taking into ccount their etiological selectivity to the main routes of transmitting the infection.     

Epidemiology of bacillary dysentery in Algeria. I. The epidemiological aspects of dysentery in Algeria

Bacterial dysentery plays an important role among infectious diseases in Algeria. A tendency to the growth of the morbidity rate has been observed. Dysentery is irregularly spread in different zones of the country. The highest morbidity rate is registered in the Sahara zone and in the eastern part of the country. The morbidity rate among the urban population is higher than among the rural population. S. flexneri prevail in the etiological structure of dysentery infection. Of all age groups, the highest morbidity rate is observed among children during the first 2 years of life. In recent years lethality varies between 2.9% and 7.5%. Patients are hospitalized mainly on the basis of clinical symptoms.     

The etiological structure of shigellosis in the USSR in recent years

The characterization of etiological structure of Shigella infection in the whole of the USSR, in individual union republics and at a number of other administrative territories of the USSR in recent years is presented. S. flexneri has been shown to prevail at the territories with unsatisfactory water supply of the population, and S. sonnei prevails at the territories with good water supply. At the former territories S. dysenteriae and S. boydii retain their etiological importance, while at the latter ones their role is insignificant. At a number of territories the infectious process has stopped: no isolation of these shigellae from dysentery patients and carriers is observed any longer. Among the causative agents of Flexner's dysentery, S. flexneri 2a, 6 and 1b (in different combinations) play the leading role.     

Relation of the epidemiological characteristics of dysentery to the biological properties of the causative agents

The main forms of the epidemic manifestation of dysentery induced by different causative agents in 1975-1980 were revealed. During these years the cases of dysentery induced by Shigella sonnei, biovar II, were found to prevail (82.0-90.1%) both at the periods between epidemics and at the periods of the seasonal rise of morbidity. The experimental infection of white mice by intraperitoneal inoculation revealed no relationship between the seasonal rise of morbidity in dysentery and the virulence of its causative agents.     

Formation of the dysentery epidemic process in three small towns]

Data are presented concerning the epidemiological analysis of Sonnei dysentery outbreaks in three towns connected by common nutrition and water supply. The epidemic processes in these populated localites were strongly interrelated. Possibilities of the effect of the water factor on the extent of Sonnei dysentery incidence were studied as well. The results of studies led to the conclusion on the presence of numerous action forms of the water factor which should be taken into consideration in carrying out prophylactic and antiepidemic measures in Sonnei dysentery.     

Use of intraspecific differentiation of Sh. sonnei for the purpose of studying patterns in the epidemic process of dysentery]

The use of complex typing of Sh. sonnei by the colicinogenic and enzymatic properties in epidemiological analysis of dysentery caused by Sh. sonnei, apart from establishment of epidemiological connections in the foci, offered a possibility of introducing significant corrections in the determination of the sizes and duration of existence of the epidemic foci, as well as in detection of the sources and factors of transmission of the infection established in epidemiological examination. Typing of Sh. sonnei also aided in ascertaining that, apart from general regularities in the individual territories, the epidemic process in individual groups of the population and in different seasons of the year could also course autonomously.     

Cellular immunity factors in dysentery]

Cellular immune response was studied in 89 adult patients suffering from various clinical forms of acute dysentery, with the use of the lymphocyte blast-cell transformation reaction under the action of a specific antigen (dysenterin) and a nonspecific mitogen (phitohemagglutinin). Functional value of T-lymphocytes proved to be retained in patients with acute dysentery; there was also lymphocyte stimulation by a specific antigen in patients with moderately severe and severe forms of dysentery during the first week of the disease. Specificity of blast-cell transformation of sensitized lymphocytes under the action of dysenterin was shown. Patients with a high percentage of the lymphocyte blast forms displayed a more rapid positive progress of the main clinical indices at the height of the disease than analogous patients with a low blast percentage in the blood. The expediency of using the blast-cell transformation reaction for differential diagnosis and prognosis of moderately severe and severe forms of acute dysentery is discussed.     

Etiologic structure of bacterial dysentery in the USSR in 1983-1985

The etiological structure of dysentery in the USSR in 1983-1985 is characterized. Sonne dysentery was found to prevail in the territories with adequate water supply, while dysentery caused by Shigella flexneri prevailed at the territories with unsatisfactory water supply. S. dysenteriae and S. boydii were found to play a limited role in the etiology of dysentery. In the presence of global pandemic, an increase in the isolation rate of S. dysenteriae I in the USSR is observed. The data on the biochemical structure of S. sonnei are presented.     

Shigellosis in the USSR: the etiological role of Shigella dysenteriae

The etiological role of S. dysenteriae in Shigella infections at different territories of the USSR in 1983-1987 is analyzed. The study shows that S. dysenteriae pertain to territories with unfavorable water supply of the population. At some of these territories, in particular the Uzbek SSR, Grigor'ev-Shiga dysentery seems to gain ground and the restoration of the area of its spread occurs. In recent years the penetration of Grigor'ev-Shiga dysentery from abroad became more frequent in the presence of the pandemic of this dysentery in the world, which caused the appearance of the disease in 17 out of 27 basic territories of the All-Union Center of Shigella Infections. The ways for increasing the control of this infection are outlined.     

The etiological structure of shigellosis in the former USSR--an indicator of the activity of the main routes of infection transmission]

The data on the etiological structure of Shigella infections in the USSR in 1988-1989 are presented. The study showed the dominating role of S. flexneri with S. sonnei also retaining great importance in Shigella infections. The process of the liquidation of S. dysenteriae and S. boydii infections began in some large cities. The domination of dysentery caused by S. flexneri and a high typhoid rate, particularly in Central Asia, were due to poor water supply of the population. The spread of dysentery caused by S. sonnei was completely independent of the water factor. The decisive role in the transmission of S. sonnei in infective doses was explained by decentralized milk supply.     

Grigor'ev-Shiga dysentery: a new epidemic threat. Its global tendencies and features of its spread

In this article, based on the data contained in literature, the development of the pandemic of Grigor'ev-Shiga dysentery, which began in 1960-ies, is followed. The stages of the formation of three powerful hyperpandemic foci in Central America, South-East Asia and Central Africa are characterized. The characterization of the epidemiological features of the spread of this disease and its clinical distinction are presented. The biological properties of the causative agent, and in particular its multiple medicinal resistance facilitating the spread of the disease throughout the world, is considered. The stable character of the foci of infection in developing countries, which actually present a threat also for this country, is pointed out. For this reason, the epidemiological surveillance on Grigor'ev-Shiga dysentery should be drastically strengthened.     

The formulation of epidemiological hypotheses by using the methods of multivariate statistical analysis

The work demonstrates the main approaches to the use of the methods of multidimensional analysis for the creation of a hypothesis on the mechanism of the epidemiological process of dysentery in organized groups. The main risk factors have been established, and their role in the formation of annual, all-the-year-round and seasonal dysentery morbidity has been quantitatively evaluated. The results of analysis show the existence of diverse variants of the alimentary route of the transmission of infection, maintaining the epidemic process of dysentery, and the necessity of differentiating measures for the prophylaxis of all-the-year-round and seasonal morbidity.     

Antibiotic therapy of acute dysentery in children with immunologic deficiency conditions

One hundred children with acute Sonnei and flexneri dysentery were followed up with respect to the infection process and main immunity indices. In 32 children the immunity indices were physiological (group 1) and in 68 children secondary immune deficiency was observed (group 2). The children were treated with aminoglycoside antibiotics and prodigiozan and it was stated that the time of recovery in the children with immune deficiency was longer by 5.2 days as compared to that in the children without immune deficiency. In the children with immune deficiency the combined use of one of the aminoglycosides, prodigiozan and lysozyme, led to a reduction of the host immunological reactivity and recovery within the same periods as those recorded for children with the physiological immunity status. It is recommended to use the antibiotic combination with prodigiozan and lysozyme in the treatment of all the forms of dysentery in children with secondary immune deficiency.     

The possibility of using the demonstration of Shigella antigens in the study of the epidemic process in dysentery

The detection of Shigella antigens in feces in accordance with the results of the passive hemagglutination test is more effective than the bacteriological method for finding out persons infected with Shigella, especially in the absence of pronounced clinical manifestations of dysentery, and can be used in the study of the mechanism of the epidemic process. The examination of two groups, each consisting of permanent and temporary members, has revealed that the use of this method for detection of the antigen makes it possible to perform the epidemiological analysis of morbidity and, in particular, to determine the source(s) of infection.     

The etiological structure of acute intestinal infections in children in the Republic of Tajikistan]

The Republic of Tajikistan belongs to the territories, traditionally hyperendemic with respect to acute enteric diseases (AED). The problem of AED still remains topical in recent years, especially among child population. The study of the etiological structure of AED in children has made it possible to establish that more than 70% of these diseases are of infectious nature. The leading role in the etiological structure of these diseases belongs to Shigella infections (32.4%), enterovirus diarrhea (12.1%) and Escherichia infections (8.9%). No significant differences in the character of the etiological structure of AED in children of urban and rural areas have been detected with the exception of enterovirus diarrhea, found to occur 2.7 times more frequently on children of urban areas (15.9%) than in those of rural areas (5.8%). The ascertaining of the etiological structure of AED in Tajikistan will make it possible to essentially increase epidemiological surveillance on AED and render it more concrete.     

The importance of Shigella boydii in shigellosis morbidity in the USSR

The etiological role of S. boydii in Shigella infections registered at different territories of the USSR in 1986-1987 was analyzed. As established by this analysis, S. boydii infection occurred mainly at the territories with unsatisfactory water supply of the population; from these territories the infection spread to ther territories of the USSR. The dominating serovars causing S. boydii dysentery, as well as Shigella infections, at different territories of the USSR was shown to be identical, which was indicative of the fact that the immunological factor had no influence on the etiological structure of Shigella infections, determined by the activity of the main routes of the transfer of infection. On the whole, S. boydii serovars 2, 4 and 1 were found to prevail in the USSR.     

Shigella-specific IgA in saliva of children with bacillary dysentery

Abstract To study the secretory immune response after Shigella infection, the anti-lipopolysaccharide and anti-Shiga-toxin response in saliva, obtained from children with confirmed shigellosis and healthy children, were determined by enzyme-linked immunosorbent assay and by Western blot. Children with infection showed high titers compared to healthy controls. After Shigella dysenteriae type 1 infection a significant change in titer could be observed in a large number of cases, in contrast to Shigella flexneri infection. It appeared that, in children living in endemic areas, infection with one serotype can give a rise in antibody titer to another serotype. This could be ascribed to polyclonal B cell activation since children in endemic areas routinely show relatively high titers to Shigella antigens. We conclude that the dynamics of salivary anti- Shigella LPS and anti-Shiga-toxin in children with dysentery indicate that it can be applied to studies of immune response in shigelosis for epidemiological and vaccination purposes.     

Evaluation of the epidemiological effectiveness of hospitalization of patients with dysentery]

The authors present materials on the study of epidemiological efficacy of hospitalization of dysentery patients by statistical analysis (calculation of tendencies, rates of increase, etc.) of the indices of focal morbidity per 1000 contacts in the total number of foci characterized by various periods of isolation of the first patient. The work was carried out on materials of two towns considerably differing by the extent of organization of public services and amenities. The results obtained pointed to the relative epidemiological efficacy of hospitalization of dysentery patients particularly marked at the territory with less favourable living conditions.     

Epidemiology of bacillary dysentery in Algeria. II. The seasonality of dysentery

Morbidity rises during the period of summer and autumn are characteristic of bacterial dysentery in Algeria. During the last 18 years no essential changes in the seasonal character of bacterial dysentery were observed in the country taken as a whole. However, in different climatic and geographical zones of the country the seasonal character of dysentery greatly varies from one zone to another and essentially differs from the seasonal character of dysentery morbidity, typical of the country as a whole for many years. The most pronounced manifestations of seasonal rises are observed in the Sahara zone. The seasonal character of dysentery is formed mainly by morbidity among patients belonging to 3 age groups. The seasonal rises of dysentery can be probably explained by the complex of social and climatic factors, as well as by the biological features of the causative agents of this disease.