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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 2  |  Issue : 3  |  Page : 213-219

Geographic characterization of the tuberculosis epidemiology in iran using a geographical information system


1 Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden
2 Mycobacteriology Research Center, National Research Institute of Tuberculosis and Lung Disease, Shahid Beheshti University of Medical Sciences, Tehran, Iran

Date of Web Publication6-Sep-2018

Correspondence Address:
Dr. Sven Hoffner
Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm
Sweden
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/bbrj.bbrj_72_18

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  Abstract 


Background: Medical geographic information systems (Medical GIS) has a pronounced capacity to help us understand infectious disease epidemiology, and the transmission of pathogens in a defined geographical area over time. This could not only help us increase the understanding of public health, but also be a most useful base for medical intervention as improved infection control where it is most needed. In this study, we applied GIS to characterize Tuberculosis (TB) epidemiology in Iran. TB, caused by Mycobacterium tuberculosis, is a severe bacterial infection that can be transmitted among humans and more than 10 million people develop active TB every year and with a mortality of 1.4 million. Methods: In this cross-sectional study carried out on 3710 tuberculosis patients who had been diagnosed in 2013 to 2017 at the National Tuberculosis Reference Laboratory, we aimed to explore the geographic and gender patterns of tuberculosis in Iran using GIS. Results: Results showed that the number of patients with tuberculosis was highest in Tehran city, despite the fact that it is the richest and most developed city of Iran and that the tuberculosis dispersion reflected by GIS revealed a significant geographical heterogeneity. Conclusion: These results could be useful to establish and implement new guidelines for effective control strategies in geographic areas with the highest prevalence of tuberculosis.

Keywords: Epidemiology, geographic characterization, geographical information system, Mycobacterium tuberculosis


How to cite this article:
Hoffner S, Hadadi M, Rajaei E, Farnia P, Ahmadi M, Jaberansari Z, Velayati AA. Geographic characterization of the tuberculosis epidemiology in iran using a geographical information system. Biomed Biotechnol Res J 2018;2:213-9

How to cite this URL:
Hoffner S, Hadadi M, Rajaei E, Farnia P, Ahmadi M, Jaberansari Z, Velayati AA. Geographic characterization of the tuberculosis epidemiology in iran using a geographical information system. Biomed Biotechnol Res J [serial online] 2018 [cited 2019 Jan 23];2:213-9. Available from: http://www.bmbtrj.org/text.asp?2018/2/3/213/240708




  Introduction Top


Tuberculosis (TB) is one of the oldest known infectious diseases. It is a highly contagious bacterial infection that can be transmitted among humans and from animals to humans. The disease is caused by Mycobacterium tuberculosis and, in most cases, it affects the lungs causing pulmonary TB which can be transmitted from a TB patient to the surrounding individuals. TB can also affect a number of other sites in the body such as bone, pericardium, kidney, abdomen, and bladder, causing the so-called extrapulmonary TB.[1] Despite significant advances in TB control, for example, in diagnosis and treatment and innovative research, TB continues to be a public health concern in most low- and middle-income countries of the world.[2]

It is a necessity to diagnose the disease at an early stage with new and cost-effective methods. Geographic information system (GIS) can be used to develop effective medical control and care for TB and set up control programs for other infectious diseases.[3],[6]

GIS has some advantages and can be used to identify the role of human relationships in transmission of the disease. Iran has an intermediate incidence of TB and the epidemiology is affected by its common land borders with TB-endemic countries such as Afghanistan, Pakistan, and Iraq.

The highest incidence of TB is in the age of 15–54 years [5] and has a major impact on the quality of life of patients and their families.[5] The issue becomes more complicated since a majority of TB patients are male who are supporting their families financially. Therefore, identifying gender difference among patients and how they are distributed in cities and regions is of paramount importance.

The National Tuberculosis Reference Laboratory (Mycobacterial Research Center) in Tehran is the national reference laboratory in Iran and pioneer in the introduction of GIS as a new tool for TB control in Iran. In this regard, this center utilized the program to register all patients that were referred to the center and diagnosed to have TB. GIS can be used to study patient dispersion, determine geographical factors involved in the incidence and transmission of the disease, perform precise statistical analysis, and assess sociodemographic predictors.


  Methods Top


Suspected TB patients were referred to the National Reference Laboratory for diagnosis. The patients' information including biographical information such as age, place of birth, nationality, and level of education was registered. Place of living and the history of hospitalization due to TB were also included in the patients' profile. Some diagnostic tests such as direct sputum smear examination and chest X-ray were conducted. After diagnosis, the patients were referred to the Tuberculosis Clinic. In addition, complementary tests such as culturing the samples, antibiogram tests, molecular analysis, and polymorphism studies were done in the National Reference Laboratory.

Direct sputum smear from 3710 patients were prepared and positive cases were reported. In smears where 10–99 acid-fast bacilli per 100 microscopic fields were detected, the answer was reported as 1+. Samples with 1–10 acid-fast bacilli detected in each microscopic field were reported as 2+, while cases with more than 10 acid-fast bacilli in each microscopic field were reported as 3+.

Patients in whom growth of non-TB Mycobacterium was seen were excluded from the study.

Along with the registration of each patient's information in hospital information system, the information was also registered in the national GIS. In addition to the demographic information, the results of diagnostic tests were recorded with precise details of the patients' addresses on the map. The results of this study and the distribution in the GIS were investigated according to the inclusion criteria of the study.

This was a cross-sectional study that was carried out on 3710 TB patients who had been diagnosed and treated from 2013 to 2017. In addition, patients who had a recurrence of TB and returned to the center with positive results of sputum smear were included in the study and their gender and geographical distribution were recorded.


  Results Top


In this study, the distribution of 3710 TB patients diagnosed and treated from 2013 to 2017 was investigated via GIS. Of the patients, 1469 (39.5%) were female and 2241 (64%) were male. The number of men with TB was higher than women [Table 1].
Table 1: Gender variations of the diagnosed tuberculosis patients

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The geographical distribution of patients among all provinces of Iran, all towns of Tehran province (counties of Tehran city), and all districts of Tehran city was separately studied.

Considering the results, the maximum number of the patients with TB was distributed in Tehran province [Figure 1] and [Table 2]. Tehran is located in the north of Iran and has a high socioeconomic status. The second province that was seen to have a large number of TB patients was Alborz province in the north of Iran.
Figure 1: Distribution of tuberculosis in Iran

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Table 2: Distribution of tuberculosis patients in all provinces of Iran

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In Tehran province, 16 counties with different socioeconomic status are located. Among all the towns of Tehran province, the highest incidence of TB was observed in Tehran city, the center of Tehran province and the capital of Iran [Figure 2]. Interestingly, the prevalence of TB patients was seen to be higher in Tehran city, although this is the richest and most developed city of Iran. Most of the health-care centers are focused in Tehran.
Figure 2: Distribution of tuberculosis in the counties of Tehran

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In the counties of Tehran which have larger and wider geographical regions, the distribution of patients' number was much lower than that in Tehran city [Figure 2]. However, counties with less population, more mountainous districts, and high access to nature had less patient's dispersion statistics.

Indeed, only 2 and 41 patients were detected in Firuzkuh and Damavand, respectively [Table 3]. The mentioned cities are located on the slopes of the Alborz mountain. However, the distribution of TB patients in Shemiranat, another mountainous county, was found to be 68. In fact, it was in the same range of counties such as Pishva and Robat-Karim with more urban and industrial areas and nonmountainous districts [Figure 2] and [Table 3]. In Varamin, 185 patients (7%) were identified [Figure 2] and [Table 3]. This county includes agricultural, industrial, and residential districts. Therefore, a significant relation between the occupation and TB distribution could not be seen. In contrast, the overcrowding factor seems to have a prominent role in TB dispersion. In sum, these results may show the importance of population congestion in TB emergence in different geographical areas. The population congestion can increase the number of patients per square meter in an area.
Table 3: Distribution of tuberculosis patients in the counties of Tehran

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A large number of patients with TB were diagnosed in different districts of Tehran city [Figure 3]. Among the districts of Tehran, the highest number of the patients was identified from the most populated district, district 4. This district is situated in the northeast region of Tehran city. This district was seen to include 11% of the total TB-active patients (178 patients) [Figure 3] and [Table 4]. In fact, in district 4, as a middle-income district, people have favorable access to public health centers and resources. Yet, overcrowding in this residential region may cause the drastic increase of TB. Thus, any importance of the socioeconomic status of the studied population could not be seen.
Figure 3: Dispersion of tuberculosis in the districts of Tehran

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Table 4: Statistics of patients with tuberculosis in different districts of Tehran

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As illustrated in [Figure 3], in districts 1, 7, and 8, dispersion of disease was the lowest. Districts 1, 7, and 8 have less population than other districts. Considering the GIS analysis, in each district, the distribution of the disease was associated with population density. For instance, the least number of TB cases was identified in districts 18, 21, and 22 [Figure 3] and [Table 4].

In this study, the distribution of gender of the patients was also studied. Most patients were male [Figure 4] and [Figure 5]. In counties with the highest emergence of TB, more than half of the diagnosed patients were male [Figure 4]. However, in three counties (Pardis, Pishva, and Varamin), most patients were female. These three counties have rural areas as well as urban areas [Figure 4].
Figure 4: Distribution of tuberculosis patients in the counties of Tehran with respect to gender

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Figure 5: Dispersion of tuberculosis in the districts of Tehran with respect to gender

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In urban and industrial districts of Tehran, a high number of patients were male [Figure 5].


  Discussion Top


Evaluation of TB dispersion in Iran with GIS revealed a geographical heterogeneity. These results could be useful to develop guidelines for more directed TB control strategies in specific geographic areas with high TB prevalence. However, further studies are required to identify variables related to high-dispersion regions. Previous studies have shown the significant effect of socioeconomic factors on the level of TB smear-positive cases.[7]

Considering the results of this study, urban and rural areas, which have high population densities and are close to Tehran metropolitan, may represent a high prevalence of TB. Indeed, numerous studies have reported the significant role of poor socioeconomic conditions including social inequality, poverty, low income, poor housing conditions, overcrowding, and social unrest in the emergence of TB.[8] According to previous works around the world, the mentioned aspects should be taken into account by health-care authorities to reduce the high burden and variations of the disease occurrence. However, only the gender of patients with TB was included in this study.

As a result, the percentage of men that were TB smear positive was almost twice that of women. This ratio was observed in most of the towns of the Tehran province as well as all districts of Tehran city. This study is the first and only spatial analysis of TB smear-positive cases in Tehran area.

The results of the present study should be analyzed in relation to the increasing information from other similar studies around the world.[8],[9],[10],[11],[12],[13],[14],[15],[16],[17],[18],[19],[20],[21],[22],[23],[24],[25],[26] The data definitely would help health-care authorities to make better decisions about developing new strategies to handle TB transmission in the studied area and direct the interventions to sites where they are most needed. The results obtained illustrate that the GIS could serve as a link between biomedical and social sciences. Without doubt, there is an increasing role of GIS in the health field. When used together with conventional infectious disease epidemiology, it will contribute to an advanced disease control. It will become possible to identify and map medically vulnerable populations and various risk factors, and their combinations, and to correlate these findings with treatment success and epidemiological trends over time. The capacity of GIS to link disease information with environmental and spatial data makes it an asset in the progression of worldwide public health. Thus, it is possible to conduct geographically based screening and use the results to develop improved programs for controlling TB based on the obtained evidences.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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  [Full text]  


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