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UDC 616.9: 616.34-002.1
RETROSPECTIVE EVALUATION OF THE EPIDEMIOLOGICAL SITUATION OF ACUTE INTESTINAL INFECTIONS OF BACTERIAL AND VIRAL ETIOLOGY IN THE PREFLOOD PERIOD
Altai State Medical University, Barnaul
G.G. Onishchenko, I.P. Saldan, C.I. Tribunsky, V.B. Kolyado, Ye.V. Kolyado
The article presents the results of a retrospective epidemiological analysis of the incidence of acute intestinal infections in prefreshet period in Altai Krai and the Republic of Altai. As a result of the analysis topical epidemiological precursors deteriorating situation in both territories before the seasonal floods were established, and the peculiarities of the morbidity of individual nosological forms in the territories of Russia with a high risk of flood development were investigated. Key words: floods, flood situation, infectious morbidity.
The state of human environment becomes especially important during the period of extreme hydrometeorological events. The analysis of literature sources revealed, that along with the economic damage caused to the society, they could lead to the development of serious medical consequences. The destruction of life support systems created an unfavorable sanitary-hygienic environment in large territories (there are formed new factors of epidemiological risk and the existing ones are activated). In that context, the emergency situations of biological and social nature quite often take place [1, 4, 5, 7, 8, 13]. According to other authors, flood destroy the infrastructure of inhabited areas, threated the life of population, which requires the evacuation of victims to more safe regions and the creation of temporary accommodation facilities for them. The indicated factors aggravate the epidemiological situation and predetermine mass infectious diseases, primarily, intestinal infections transmitted by water and food. In the structure of acute intestinal infections increases the role of noro- and rotaviral infections [2, 3, 6, 9, 10, 11, 12]. The effect of water on biocoeno-sis of natural focuses preconditions the realization of sanitary-epidemiological for the population situated in the flood zone, which are realized by the increase of morbidity of such dangerous infectious diseases, as cholera, acute viral intestinal and other infections, moreover, over the last decades, there has been indicated a number of new viruses - causative agents of dangerous infections.
Objective: retrospective epidemiological analysis of morbidity of acute intestinal infections among the population of Altai Krai and the Altai Republic in the preflood period.
Materials and methods
The retrospective analysis of morbidity of population of Alta Krai and the Altai Republic was performed on the basis of the statistical tools "The
information about infectious and parasitical diseases" (form No. 1) for the period of 2004-2013. The statistical data processing was conducted be means of common methods of analysis: calculation of intensive and extensive indexes, creation and processing of time series, mean values (X), diversity of their characteristics (c) and coverage errors (m), calculation of regression coefficients (Rx/y), approximation. To state the degree of de-terminacy of variation of criterion variable by predictors, there was implemented the method of regression analysis with construction of trend lines. As a result of regression analysis, there were obtained regression equations with calculated values of regression coefficients. The significance of obtained regressional dependences expressed by mathematical equation was selected on the basis of the approximation coefficient R2>0,5. The coefficients of determination show, that the most preferable is the polynominal trend, and the least preferable - the linear one. Graphical support and data processed were performed on a personal computer Intel Pentium by means of standard license programs («SPPS Statistics 20», Excel) in Windows 7 operating environment.
Results and discussion
In Altai Krai in the period from 2010 to 2014 the total volume of infectious diseases is dominated by acute upper respiratory infections, which constitute 93,0%, the second position is occupied by airborne infections - 4,5%, the third position is occupied by acute intestinal infections - 1,5%, the fourth position - by zoonotic and natural focal diseases - 0,1%. The dynamics of acute intestinal infections morbidity among the population of Altai Krai in the period from 2004 to 2013 is characterized by annual increase of the index from 377,10/0000 to 397,80/0000, by the average annual rate of growth (R 0 6% the long-term average annual index (xp±m)° constituted 390,2 ± 4,0°/0000. The trend had a statistically significant character, R2>0,5. The AII
(acute intestinal infections) morbidity of unknown
etiology also grew from 245,30/0000 to 2790/0000 (Rgr
1,4%, R2>0,5, X ±m = 273,7±3,3%000), the AII of de' ' P 0000"
termined etiology - from c 89,7^00 to 116,60/0000 (Rgr 3,0%, R2>0,5, Xp±m = 114,3 ± 2,20/0000) (Figure 1).
The epidemiological situation of dysentery in Altai Krai for the studied period can be characterized as favorable, the index of bacterial dysentery morbidity decreased from 42,080/0000 in 2004 to 2,20/0000 in 2013 by average annual rate of decrease (Rde) 28,0% (R2>0,5), the long-term average annual index constituted 2,2 ± 0,30/0000. The salmonello-sis morbidity reduced from 37,60/0000 to 37,20/0000 (R 3,0%, R2>0,5, X ±m = 36,5 ± 1,2%n nn), which
^ de. ' ' P 0000/
indicates the effectiveness of measures to control the stated group of infections conducted in the ter-
ritorial entity of the RF. There had been registered the cases of typhoid fever incidence: 1 case in 2006 and 1 case in 2009. The dynamics of enterovirus infections morbidity (further - EVI) has a multidirectional character: the morbidity of viral hepatitis A infection, noroviruses (for the period from 2010 to 2013) and other AII has an upward (negative) trend. The morbidity of ACI caused by en-teropathogenic coliform bacteria (further - EPCB) has a downward (positive) trend. The evaluation of the epidemiological situation of enterovirus infections morbidity in Altai Krai in the period from 2004 to 2013 shows, that the rotavirus morbidity in the territorial entity has a trend to growth from 8,200/0000 to 53,50%,000 (Rgr. i5,90^ R2>0,5, X±m = 258,1 ± 11,2°/0000).
Figure 1.
Dynamics of morbidity of AII of bacterial etiology in 2004 - 2013 in Altai krai (per 100 thous. population). (The diagram is built on the basis of Rospotrebnadzor administration of Altai Krai)
It should be noted, that the rotavirus infection is characterized by high relative share (24,0%) in the structure of AII of determined etiology, possesses expressed seasonality during the winter-spring period, high contagiosity, low infective dose, high activity of water and community transmission, resistance in external environment and forms virus carriage. In this regard, it is necessary to monitor the circulation of rotaviruses in the environment, particularly, in the main water, to conduct the rotavirus antigen examination of persons with clinical manifestations of diarrhea. The intensity of EPCB AII morbidity reduction among the population annually constituted 4,5%, which allowed to stabilize the annual average index at the level of 7,5±0,60/0000. The level of morbidity of other AII increased from 89,70/0000 4
in 2004 to 116,670000 in 2013 (R 3,0%, R2>0,5, X ±m
' ' 0000 \ gr. ' ' P
= 109,1±2,l0/0000). The highest levels of morbidity were registered in 2011 (P=127,80/0000) and in 2011 (P=135,10/0000). In the long-term dynamics of viral hepatitis A there is determined the annual average rate of growth 0,5% (R2>0,5), the average index for the studied period constituted 4,2 ± 0,40/0000. In this regard, there can be differentiated 2 period in the long-term dynamics of viral hepatitis A epidemic process. Thus, from 2004 to 2009 the dynamics of viral hepatitis A morbidity was characterized by annual reduction of the index from 6,00/0000 to 1,60/0000 (Rde.23,3%), since 2010 the morbid00y
acquired an upward trend from 3, 50/0000 to 6,30/0000 (Rgr.21,4%). 0000 0000
For the whole studied period in 2010 there were firstly registered 5 cases of norovirus infec-
tion, while the morbidity of AII caused by norovi-ruses grew from 0,20/0000 in 2010 to 2,10/0000 in 2013 (R2>0,5). In the period of 2011-2013 in Altai Krai there were registered 9 hotbeds of group (5 and more cases) diseases, caused by noroviruses, with the total number of diseased - 97, including 77 children. In the structure of infectious morbidity of the Altai Republic AII constitute 4,0% occupying the 3rd position after acute upper respiratory infections (91,1%) and chickenpox (5,0%). The dynamics of AII morbidity among the whole population of the Altai Republic for the period from 2004 to 2013 is characterized by annual growth of the index from 430,80/0000 to 540,50/0000, by average annual rate of growth 2,6% (R2>0,5), the average long-term index constituted 607,3 ± 17, 20/0000. The leading position in the long-term dynamics is taken by acute intestinal infections of unknown etiology (further - AIIUE), the morbidity of which increased from
230,50/0000 to 285,20/0000 (Rr. ^ R2>0,5, X±m =
266,7±11,4). The analysis of annual AIIUE morbidity indicates year-round registration of diseases without expressed seasonality.
In the age structure of AIIUE diseased population the share of child population constituted from 57,0% to 65,0%. It should be mentioned, that sporadic cases of morbidity in organized child groups do not have further proliferation and, as a rule, are not connected with the child presence in the child-care institution. In 2007 there was registered the outbreak of AIIUE in the Altai republic, which had a food nature, 27 people suffered, the diagnoses was bacteriologically confirmed - in all patients there was detected S.enteritidis. The results of the retrospective epidemiological analysis showed, that the long-term dynamics of AII of determined morbidity among the population of the Altai Republic for 10-year period was characterized by the trend to growth from 128,10/0000 to 215,00/0000, with the average annual rate of growth 5,9% (R2>0,5). The average long-term morbidity level constituted 258,1 ± 11,20/0000 The salmonellosis morbidity grew from 24,70/0000 to 27,50/0000 (Rde. U0^ R2>0,5, X±m = 26,4±3,6). At the same time, the index of bacterial dysentery morbidity decreased from 46,90/0000 in 2004 to 12,80/0000 in 2013 by average annual rate of decrease 13,4% (R2>0,5), the average long-term index constituted 55,4 ± 5,20/0000.
In 2013 the index of salmonellosis morbidity constituted 27,50/0000, there were registered 58 cases. In 2013 the share of children at the age under 17 constituted 51,7%. The outbreak salmonellosis morbidity was not registered. In the structure of infectious morbidity of the Altai Republic for the period of 2004-2013 AIIUE holds the 1st position, there share is 44,0%. The 2nd position is occupied by AII of determined etiology, 43,0%. The 3rd position is occupied by dysentery constituting 9,0% and the 4th position - by salmonellosis constituting 4,0%. In the Altai Republic along with bacterial
intestinal infections are widespread acute intestinal infections of virus etiology. The carried analysis showed, that for the period from 2004 to 2013 the average long-term rotavirus morbidity index constituted 137,1±8,20/0000, viral hepatitis A (VHA) - 3,0±1,20/0000, other determ ined AII - 524,7±16, 00/0000. In the structure of AII of determined etiology a considerable share is occupied by rotavirus diseases, the morbidity of which has a clear trend to growth. In 2004 there were registered 31 cases of rotavirus infection, the index of morbidity constituted 15,30/0000, in 2013 there were registered 254 cases and the index grew up to 120,50/0000, by average annual rate of growth 25,7% (R2>0,5) (Figure 2).
In the period from 2011 (179,40/0000) to 2013 (120,50/0000) the morbidity of gastroenteritis of rota-virus etiology decreased by 32,8%. The reduction of infection was registered among all age groups of child population. The disease was primarily registered among the children under 6, who in 2013 constituted 89,3% (in 2012 - 87,0%, in 2011 - 88,9%). Out of total number of diseased the relative share of children under 17 in 2013 constituted 93,3% (in 2012 - 91,2%, in 2011 - 87,0%). In 2013 there were continued the studies of eternal environment objects (central water supply, decentralized water supply) for the presence of rotavirus antigen. No positive results were obtained. Considering a quite high rate of morbidity of rotavirus infection, there is conducted annual examination of food unit workers for intestinal infections, including viral (rota- and noroviruses). Thus, in 2012, there were examined 480 people, in 2013 - 520 people. In case of positive results there were provided corresponding treatment. VHA morbidity on the territory of the Altai Republic has a sporadic character, there are registered single cases in the city of Gorno-Altaisk and separate districts (Maiminsky, Ust-Kan-sky).
The morbidity index reduced from 13,90/0000 in 2004 to 3,30/0000 in 2013 by annual average rate of decrease 14,7% (R2>0,5). In 2013 VHA morbidity among the population under 17 constituted 14,30/0000, including the age group of 15-17 years -51,80/0000, among the population over 18 - 2,60/0000. In the territorial entity there are provided timely antiepidemic measures in case of morbidity. One of the aims of VHA prevention is the conduction of preventive vaccination, especially for exposed persons in the hotbeds, and also for children and decreed workers. In the period from 2008 to 2013 in terms of "Preventive vaccination" subprogram realization 3113 people were vaccinated against VHA. To monitor the material of laboratory tests of patients with VHA and objects of external environment by means of modern molecular diagnostics methods there was established cooperation with Federal Budget Institution of Science "Central Research Institute of Epidemiology". In order to monitor the circulation of intestinal
viruses in 2013 there were studied 102 samples of surface waters and 182 samples of main water for the presence of antigen of rotaviruses, norovi-ruses, the results were negative. During the study
period the morbidity of other AII of determined etiology grew from 358,60/0000 to 500,20/0000, by average annual rate of growth 3,8% (R2>0,5), the average annual index constituted 524,7±16,00/0000.
Figure 2.
Dynamics of morbidity of AII of virus etiology (VHA, rotavirus, determined AII, etc.) for the period of 2004-2013 in the Altai Republic (per 100 thous. population). (The diagram is built on the basis of Rospotrebnadzor administration
of Altai Krai)
Conclusion
As a result of the conducted retrospective ep-idemiological analysis there was determined the level, structure and dynamics of infectious morbidity in the preflood period in the territories of Altai Krai and the Altai Republic, providing the solution of problems of epidemiological diagnostics in order to substantiate advanced planning of epidemiological measures. The methods of epi-demiological analysis included the study of trend and peculiarities of morbidity of separate nosologi-cal forms in the territories of the RF with high flood risk. By the statement of contents of retrospective epidemiological analysis the emphasis was focused on the process of epidemiological reasoning based on the conducted calculations. According to the analysis, there were stated the current precursory signs of the aggravation of the situation in both territories in the preflood period: AII morbidity ill-being, growth of salmonellosis morbidity (the Altai Republic), growth of infectious diseases of virus etiology, caused by rota- and noroviruses.
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Contacts:
Corresponding author - Saldan Igor Petrovich, Doctor of Medical Sciences, Professor, Rector, Head of the Department of hygiene, ecology and health and safety of the FSBEI HE Altai State Medical University of the Ministry of Health of the Russian Federation, Barnaul. 656038, Barnaul, Lenina Prospekt, 40. Tel.: (3852) 566800. Email: [email protected]
