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The influence of coli form bacteria (CFB) contamination in urbanized areas on acute enteric infection (AEI) morbidity of population.

Introduction

Urbanization of territories is inevitably accompanied by environmental pollution (Methods for soil microbiological control, 2004). Biological factors (bacteria, viruses and geo-helminthes) take a special place among environment pollution factors, the prevalence of which leads to the emergence of infectious diseases and invasions among the population (Kolodin and Belyh, 2007).

In this aspect, infections (acute enteric infections (AEI), hepatitis A, helminthes), which agents during their biological cycle have a period of exposure on external environment objects, represent topical areas of research.

In Kazakhstan, studies of bacterial contamination of the territory and its relationship to morbidity of the population have not been conducted so far. In this connection, the study and estimation of biological indicators--markers of the microbial contamination of environmental objects, determination of the causal relationships between revealed factor and state of population health in Kazakhstan becomes important and necessary.

Materials and methods

Observations were conducted in the towns and villages in five regions of Kazakhstan, which differ by the nature of industrial and agricultural activities.

Soil samples taken from various points within each subject's locality served as materials for the study. Collection of soil samples, its handling, preparation for analysis and research for the presence of bacteria was carried out by the described procedures (Dicker, 1998; Ecological and epidemiological study of health status and statistical methods of analysis, 2008).

The number of soil samples (in [??]) with coli form bacteria (CFB) an activity index of 100-1000 was taken as a biological stress indicator in the soil.

Data on the AEI incidence (except in cases of the dysentery and salmonella) in the studied population settlements were obtained in local offices of State Sanitary Inspection.

The likely impact of microbial contamination of the soil on the AEI incidence among population was accepted as the null hypothesis. Epidemiological surveillance of the population morbidity in different settlements was fulfilled using case-control method (Ecological and epidemiological study of health state and statistical methods of analysis, 2008).

Epidemiological parameters, common to the studied areas and necessary to assess adverse effects of pollution on the population health were calculated using bio-statistical analysis of the "four fields" (Dicker, 1998), as well as by a computer program to "evaluate the risks with confidence intervals."

Results and discussion

The resulting data of biological stress on the ground (in [??]), average incidence of AEI (in [??]), odds ratios (OR), relative risk (RR) with confidence intervals summarized across the cities studied are shown in Table 1.

The epidemiological parameters of the studied cities given in the Table 1 were received in the comparison with data for Shuchinsk--the control city.

As seen from Table 1, rank number of cities by biological stress indicators on the soil and the incidence of AEI are in decreasing order from the Ust-Kamenogorsk--Taraz--Aktau. Values of OR (ratio of probability of being exposed in patients to the same index in healthy people) and RR (describing the probability of incidence from the effects of harmful factor) range from 1.36 to 1.78 and from 1.56 to 2.22, respectively. Significance level of 0.05 indicates on the reliability of the data.

A similar analysis of data on small towns is shown in Table 2.

As can be seen, OR and RR rates for cities Temirtau and Ekibastuz are above 1.0, indicators of CFB index and incidence of AEI is also higher than in the control Shushinsk city (29.1 and 91.3); this corresponds to the reliability of the values of the studied parameters. In Zhanaozen, OR and RR values are in the range of 1.0, indicating a lesser likelihood of the incidence of contamination of the soil. Apparently, this is a consequence of almost identical conditions of CFB index in Zhanaozen (33.5) and Shushinsk (29.1), as well as the morbidity of the population (97.4 and 91.8, respectively).

Table 3 shows the results of the analysis of indicators of soil contamination by microbes and the incidence of AEI, as well as calculations of the OR and RR for rural settlements.

As can be seen in villages Glubokoe, Sozak-Shalakorgan and Chkalovo, with sufficiently high values of the CFB index in the soil, high rates of morbidity is observed. In these villages RR and OR values are above 1.0, indicating the impact of contamination of the territory on the incidence of AEI. A somewhat different picture is observed in the village of Solnechniy: with a high level of CFB index (99.0), a low incidence rate occurred (48.5), which is almost close to that in the control village Borovoe (38.3), which determines the value of OR and RR below 1.0.

Apparently, in the rural areas there are difficulties with the identification and registration of patients. There is a need to pay attention and improve the situation.

This study shows that in urbanized territories there is quite a high contamination rate of soil by microorganisms. There is a relevance indicator between contamination and incidence of AEI. The values of OR and RR indicate the likely impact of soil contamination on AEI.

References

Dicker, R. (Ed.), 1998. Principles of epidemiology. Introduction to practical epidemiology and biostatistics, Saint-Petersburg: MEDLINE

Ecological and epidemiological study of health status and statistical methods of analysis. 2008. [Ekologoepidemiologicheskoe izuchenie sostoyaniya zdoroviya naseleniya i statisticheskie metody analiza (metod.recomend.)], in Russian, Karaganda

Kolodina, L., Belyh, B., 2007. "Microbiological contamination of soil," Electronic scientific journal "Investigated in Russia" [Elektronnyi nauchnyi zhurnal "Issledovano v Rossii"], pp.21-25

Methods for soil microbiological control, 2004. Methodical recommendations [Metody mikrobiologicheskogo kontrolya pochvy. Metodicheskie rekomendii], in Russian, approved by the chief state sanitary doctor of the Russian Federation, 24.12.2004, No.FTS/4022

Maria Omarova, Lyazat Orakbay, Idelbay Shuratov, Aizhan Dzhumagalieva, Asya Kenzhebaeva

Scientific Center for Hygiene and Epidemiology, Almaty, Kazakhstan
Table 1. Typical epidemiological indicators of the impact
of contaminated by bacteria territories on the aei incidence

                                  Ust-       Taraz   Aktau
                               Kamenogorsk   city     city
                                  city

Index of CFB group                50.0       28.6     27.7
Indicator (%ooo)                  206.2      183.2   138.3
AEI rank number                     1          2       3
The significance level            0.05       0.05     0.05
  Lower confidence interval       0.18       0.16     0.11
  Upper confidence interval       28.77      25.14    22.0
The odds ratio (OR)               1.78       1.64     1.36
  Lower confidence interval       0.22       0.20     0.15
  Upper confidence interval       3.32       2.84     1.95
Relative risk (RR)                2.22        2.0     1.56
Ecological share                  54.9       50.0     37.7

Table 2. Typical epidemiological indicators of impact of soil
contamination by bacteria on the AEI incidence in small towns'
population

                               Temirtau   Ekibastuz   Zhanaozen
                                 city       city        city

Index of CFB group               60.0       53.8        33.5
Indicator (%000)                181.2       117.6       97.4
AEI rank number                   1           2           3
The significance level           0.05       0.05        0.05
  Lower confidence interval      0.16       0.08        0.05
  Upper confidence interval     25.14       20.52       18.58
The odds ratio (OR)              1.64       1.21        1.02
  Lower confidence interval      0.20       0.12        0.09
  Upper confidence interval      2.84       1.54        1.00
Relative risk (RR)               2.0        1.33        1.00
Ecological share                 50.0       24.9         0.0

Table 3. Indicators of impact of biological stress on the soil on
the incidence of AEI among the population

                                  Glubokoe        Sozak-
                                  village      Shalakorgan
                                                 village

Index of CFB group                  83.3           53.3
Indicator (%000)                   206.2          183.2
AEI rank number                      1              2
  Lower confidence interval         0.16           0.04
  Upper confidence interval        143.8          85.21
The odds ratio (OR)                 2.66           1.33
  Lower confidence interval         0.24           0.09
  Upper confidence interval        10.79           2.19
Relative risk (RR)                  4.75           1.75
Ecological share                    78.9           42.9

                                  Chkalovo      Solnechnyi
                                  village        village

Index of CFB group                  66.6           99.0
Indicator (%000)                   138.3           43.5
AEI rank number                      3              4
  Lower confidence interval         0.02           0.01
  Upper confidence interval         79.9           8.0
The odds ratio (OR)                 1.11           0.9
  Lower confidence interval         0.06           0.05
  Upper confidence interval         1.36           0.99
Relative risk (RR)                  1.24           0.99
Ecological share                    19.9          -0.005
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Article Details
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Author:Omarova, Maria; Orakbay, Lyazat; Shuratov, Idelbay; Dzhumagalieva, Aizhan; Kenzhebaeva, Asya
Publication:Medical and Health Science Journal
Article Type:Report
Geographic Code:9KAZA
Date:Oct 1, 2012
Words:1361
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