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ГУ «Луганский государственный медицинский университет»
ГЗ «Луганский государственный медицинский университет»
91045, кв. 50-летия Обороны Луганска, 1 г, Луганск, Украина
91045,50 Rokyv Oborony Luganska Block, 1G, Lugansk,Ukraine
Introduction. Data from numerous studies indicate that the character of the development of various diseases, mortality and fertility indexes, parameters of the status of all functional systems of the human body and animals, the nature of the chemical reactions mostly dependent on heliogeophysical factors [1, 2, 5, 8, 10]. Of particular interest involves the problem of disease due to solar activity. History studies of the effect of space weather-being goes back to Jonathan Swift (1724).  Space weather here means a multifaceted impact of unsteadiness of the sun or the solar activity on the Earth's processes. Now there are accumulated a lot of facts about the relationship of life on Earth with solar activity: these are people morbidity statistics, and population size of animals, and crops agricultures [7, 8]. Most obviously this relationship is manifested in their correlation with one of the cycles of solar activity, in a period of 11 years. In this period the number of spots on the Sun has being changed.
Nowadays, viral hepatitis A (VHA) belongs to a group of socially significant diseases, the relevance of which is due to the increasing number of outbreaks, moving of the high morbidity indexes for older age groups and, as a result, increase the frequency of severe infections, frequent stratification of VHA with chronic hepatitis B or C and / or addiction, and poor prognosis of the disease [1, 3, 4, 9].
It is considered that decline of the epidemiological situation regarding VHA largely determined by social factors, however, as in other diseases it should be taken into account an environmental factors , particularly, solar activity, which are not just important, but probably paramount.
In this connection, the aim of our study was to investigate the relation of cyclic development in epidemic process of VHA in Ukraine in the period from 1975 to 2011, with the variations of space weather.
Connection with scientific programs, plans, themes. Paper work is done in accordance with the main plan of research work SE "Luhansk state medical university" and is a piece of research themes: "Epidemiology and prevention of viral hepatitis A in a large industrial region» (№ state registration 0112U002935 ).
Materials and methods of research. The analysis was carried out on the statistical data on the incidence of VHA among the population of Ukraine for the period 1975-2011 years, which were provided by the Ministry of Public Health of Ukraine. The data concerning the solar activity have been provided by hydrometeorology center. The level of solar activity was estimated by average annual values of Wolf numbers W (relative number of sunspots and their groups).
The target complex was represented in the form of distribution by ranking (in ascending or descending order of the analyzed quantitative trait), then the characteristics of this complex was presented, indicated the central meaning of the values of (arithmetic mean, median, mode), time-swing variation, the shape of the curve distribution . The main purpose of this approach is the ability to identify the relationship between parameters. Thus, in addition to traditional measurements and subsequent calculations in the analysis of statistical data there was conducted the detection of functional relationship between influencing factor (in this case it is solar activity) and registered (under study) quantity (in this case it is the morbidity rate of hepatitis A) [ 6].
Results and its discussion. The dynamics of the morbidity of VHA in Luhansk region is uneven that is characterized by the alternation of periodic rises and downs. The epidemic rise of the morbidity, which began in 1997, practically reached the indexes of the previous rise. In the cyclic rise of morbidity in 1997-2008 the intensive rate per 100 thousand population ranged from 5.53 to 119.6. Low level of the morbidity occurred in the period in 2008. Since 2009, there is a regular increase in morbidity in the region, associated with the cyclical patterns of the epidemic process of VHA in Luhansk region.
Analysis of typical seasonal dynamics of VHA disease confirmed the characteristic autumn and winter season for countries of the northern hemisphere. In this regard, our data are consistent with the literature data. On the season, as well as other manifestations of the epidemic process, there reflected peculiarities of mechanism of transmission of infection in general and the activity of individual factors. Using seasonally adjusted index there have been set periods of morbidity during the year that were caused by the influence of seasonal factors.
The intensification of the epidemic process in Luhansk region is noted in the autumn-winter period (August-February) and lasts seven months, when the morbidity level exceeds that in the off-season in 2.5-3.6 times. The maximum morbidity indexes have been recorded in October, November and December (long-term average index is 22.0, 23.5 and 21.0 per 100 thousand of the population, respectively), minimum - in June and July (intensive index of 6.9 and 6.7 per 100 thousand)
There is a certain correlation between solar activity and the incidence of hepatitis A in Luhansk region. To confirm this assumption, the correlation coefficient was determined, which is equal to 0.484 and tested the hypothesis of the presence of the link by Student criteria. The closer the coefficient to unity, the greater is the relationship between the studied events. If tr> ttable, then the hypothesis of connection is accepted, otherwise it is absent.
To test the hypothesis of connection’ presence there has been identified the St. criteria using the formula:
The results are presented in the table.
Critical values of St.criteria for significance level
As the table shows, the hypothesis of connection’ presence is accepted at a significance level of 0.1, 0.05 and 0.01.
Analysis of the incidence of VHA in the years 1975-2011 showed that the ascent or decline of morbidity is a period of 3 years up to a maximum / minimum of solar activity (Fig.). These results are a practical proof of facts of modern scientific literature about the correlation of epidemiological situation of infectious diseases with the cycles of solar activity on the territory of Ukraine.
There has been determined the correlation between the incidence of VHA and indexes of individual cosmic factors on the epidemic process of VHA can’t be accidental. The process of forming of perennial epidemic cycles involves many factors and mechanisms (new variants or types of agent, immune status, the proportion of people with compromised immune systems, etc.), determine and masking effect of solar activity on the epidemic process of VHA.
The results of our study showed the following:
- development of disease of VHA is characterized by cyclic, that is after the rise there is deceleration of the growth of disease and a slight decline;
- it is noted the existence of a significant linear relationship between the incidence of VHA in Luhansk region and the Wolf numbers
- changes in incidences of VHA are characterized by a certain vibrational character, but in the structure of their cyclic recurrence the well-known periods of solar activity with the lag for three years are noticed.
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