Epidemiological features of hemorrhagic fever with renal syndrome in 2006-2007 and 2016-2017 in the voronezh region

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BACKGROUND Hemorrhagic fever with renal syndrome (HFRS) is a viral infection that is isolated from all natural focal diseases due to the high level of incidence for many years. About two hundred thousand people get sick HFRS every year in the world[1]. The etiological role of 5 types of Hantaviruses in the structure of the incidence of HFRS in Russia is proved: Huntaan, Amur, Seoul - in the far East, Puumala and Dobrava in the regions of the European part of the country,in particular, in the Voronezh region, which is an endemic area for HFRS. The natural focus of the pathogen circulation is located in Verkhnekhavsky district, landscape features and species structure of rodents which create optimal conditions for this. Despite the fact that the percentage of mortality from this disease is low, there are socio - economic problems, because most of the patients are men of working age[2]. AIM Research the epidemiological features of outbreaks of hemorrhagic fever with renal syndrome in the Voronezh region in the period 2006-2007 and 2016-2017. METHODS Research design Retrospectively- descriptive analytical study with elements of statistic analysis. Conformity criteria The average long-term incidence of hemorrhagic fever with renal syndrome in the Voronezh region was 0.5 per 100 thousand people. Research facilities The studies were conducted on the basis of the center of hygiene and epidemiology in the Voronezh region. The General conclusions of the study could be influenced by such factors as the appeal of the population for medical care and, consequently, the registration of cases of the disease, the accuracy of diagnostic studies of biological material of patients, as well as the quality of the Department of prevention of natural focal infections. Research duration The duration of the retrospective analysis was 40 years (from 1978 to 2018) with a detailed analysis of periodic rises in the incidence rate, in particular, in 2007 and 2017. Medical procedure description Observation of patients, collection of biological material for analysis, diagnostic determination of the level of at in the blood serum with reagents the VectoHanta IgM. The main research outcome The minimum level of incidence of hemorrhagic fever with renal syndrome was revealed in 1983, 1984, 1986, 1993 and 1998 and was equal to 0.04 per 100 thousand of us. The maximum level of morbidity was registered in 2007 and amounted to 6.54 per 100 thousand of us. In General,the incidence did not exceed 1 per 100 thousand of us until 2000 inclusive, after which the situation began to change for the worse. Additional research outcomes In the analysis of forms No. 003/y "Medical card inpatient" was revealed that most of the patients suffered from the disease in the form of moderate severity flow. When collecting the epidemiological history of established cause-effect connection of the disease with a visit to the natural focus. Subgroup analysis From December 2006 to March 2007, the absolute number of cases was 194, including 14 children. The epidemic process involved children of all ages, for except for children under 1 year. In 2017, 31 cases were registered for the territory of the Voronezh region, of which 35% were residents of rural areas and 65% were urban residents. The vast majority of cases are working aged males. Methods for registration of outcomes To register the results of the study were used pivot tables and various types of charts built in the program Microsoft office Excel 2007. Statistical analysis The principles for calculating the sample size: the sample size was not pre-calculated. Methods of statistical data analysis: the method was used method of statistical observations, including organized collection and further processing of information from the calculation of intensive and extensive indicators. Processing the data was carried out using the program Microsoft Office Excel 2007. RESULTS Research sample (participants/respondents) The objects of the research were the following data sources: statistical form reporting No. 2 "Information about infectious and parasitic diseases", "Review abundance status of small mammals and arthropods - carriers and carriers of natural focal diseases, epizootological and epidemiological of the situation in the natural foci of zooanthroponosis in the winter and spring of 2016 - 2017 and the forecast for the summer and autumn of 2017 in the Voronezh region. " Primary findings HFRS incidence rates on the territory of the Voronezh region in 2006-2007. exceeded the data for the Russian Federation by almost 2 times [3]. This was preceded by hot and rainy summer; such weather conditions contributed to late harvest, which led to an abundance and availability of food for rodents. As a consequence - an increase in the number last. The onset of cold weather contributed to the migration of the source of infection in the home people and household premises (sheds, warehouses, cellars). This explains the large the number of new cases in the autumn and winter periods. The species composition of meadow-field stations was dominated by gray vole (45%), red vole (65.3%), in settlements - house mouse (53.7%). Infection of rodents in the Voronezh region with Hantaviruses was about 78%, which exceeded the same indicator in the neighboring regions: Lipetsk (57%) and Kursk (30%). Moreover, generally, infection in closed meadow-field stations was higher than in open ones. In the settlements of the Voronezh region infection of the field mouse prevailed (38.5%). Basically, the number of cases was men of working age, which is probably connected with the lifestyle and character of their employment. Diagnosis of blood serum of HFRS cases in 2006-2007 showed that in 87% of cases were found virus Dobrava and 13% for Puumala virus. The increase in morbidity in the winter of 2016-2017 was preceded by a moderately warm, snowy winter without temperature jumps. Such weather conditions can also be called positive for rodents. The incidence in 2016-2017 was 5 times lower than in 2006-2007 In the species composition in the meadow-field habitats dominated field mouse (54%) and voles of the genus Microtus (25%). In the settlements of the Voronezh region of circulation of the causative agent of HFRS was not detected. The analysis of 32 districts of the Voronezh region revealed the highest percentage of infected individuals in the Verkhnekhavsky district in the forest mouse (36.8%) and field mouse (31.6%). Identification of the pathogenic agent in the blood serum of patients in 2014 determined the Puumala virus in 100% of cases, in 2015 67% found the Puumala virus and 33% - to the virus of good. The results of the study of serums in 2017 revealed 50% of cases of at to the virus of good and 50% - to the Puumala virus. Additional findings Seromonitoring of the population for the presence of antibodies (at) to the causative agent of HFRS revealed that in 2017 the proportion of seropositive people is 3 times higher than in 2016 and more than 6 times higher than the results of 2015. As for the course of the disease, the predominant forms of the disease of moderate severity with severe intoxication syndrome, as in previous years. During the periods of outbreaks, there is a downward trend in the number of areas where cases have been registered. Undesirable phenomena Undesirable phenomenon are absent. DISCUSSION Summary of the primary research results Based on the results of the study, we can draw conclusions about the relationship between climatic conditions and the subsequent increase in the number of cases of hemorrhagic fever with renal syndrome. In the species composition of small mammals there were no significant changes, their infection in the settlements of the Voronezh region decreased. Increased the etiological role of Puumala hantavirus in analogy with previous years. Discussion of the primary research results Cases of hemorrhagic fever with renal syndrome in the Voronezh region have been noted for many years, mainly in the autumn-winter period, which coincides either with the peak of the number of rodents, or with their migration to people`s homes. In long-term dynamics characteristic periodic rises of morbidity are traced. Among the sick, men of working age prevail, which can be associated with their professional activities. Also, when carrying out seromonitoring a the healthy population, has seen an increase in the number of people who are found to have at to hantaviruses. It is probably due to the course of the disease in hidden and mild form, about which people do not turn to treatment-and-prophylactic institutions, or latent immunization. In General, the predominant form of moderate severity of hemorrhagic fever with renal syndrome. There is a limitation of the area of HFRS in the Voronezh region. Research limitations These objects of research depend on the level of equipment of diagnostic laboratories areas, skills and experience of medical personnel, the circulation of the population for medical care. The results concerning the species composition of small mammals may be influenced by the efficiency of zoological groups, the frequency of their visits to the rodent habitat. CONCLUSION On the territory of the Voronezh region recorded sporadic incidence of HFRS with moderate periods of rise and fall. The results of studies of blood serum for antibody to the causative agent of HFRS has shown that in recent time increased the number of diseases caused by Puumala hantavirus. The species mouse is dominated by a field mouse, its share in the structure has increased 2 times (2007-26%, 2017.-54%). Infection of rodents in human settlements has declined, however, in Lugo the field plots in the infection field mice increased 1.5 times. The number of areas where cases have been reported has decreased, indicating the effectiveness of preventive and anti-epidemic measures. Anthropogenic impact on the natural habitat of the source of this infection leads to their migration to new areas and only exacerbates the epidemic situation. Given the fact that the effect of deratization is short due to the update rodent populations, it is necessary to look for new ways and methods to neutralize natural foci of infection.

About the authors

V A Knyazeva

N.N. Burdenko Voronezh State Medical University

Voronezh,Russia

N P Mamchik

N.N. Burdenko Voronezh State Medical University

Voronezh,Russia

N Y Samodurova

N.N. Burdenko Voronezh State Medical University

Voronezh,Russia

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