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Open Access Research article

Prevalence of pulmonary TB and spoligotype pattern of Mycobacterium tuberculosis among TB suspects in a rural community in Southwest Ethiopia

Amare Deribew12*, Gemeda Abebe23, Ludwig Apers4, Alemseged Abdissa4, Fetene Deribe4, Kifle Woldemichael1, Chali Jira5, Markos Tesfaye6, Jafar Shiffa7, Abraham Aseffa8, Mesele Bezabih3, Tadiye Abeje8 and Robert Colebunders24

Author Affiliations

1 Department of Epidemiology, Jimma University, Jimma, Ethiopia

2 University of Antwerp, Antwerp, Belgium

3 Department of Laboratory Sciences and pathology, Jimma University, Jimma, Ethiopia

4 Institute of Tropical Medicine, Antwerp, Belgium

5 Department of Health service management and Planning, Jimma University, Jimma, Ethiopia

6 Department of psychiatry, Jimma University, Jimma, Ethiopia

7 Department of Internal Medicine, Jimma University, Jimma, Ethiopia

8 Armour Hansen Research Institute, Addis Ababa, Ethiopia

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BMC Infectious Diseases 2012, 12:54  doi:10.1186/1471-2334-12-54

Published: 13 March 2012

Abstract

Background

In Ethiopia where there is no strong surveillance system and state of the art diagnostic facilities are limited, the real burden of tuberculosis (TB) is not well known. We conducted a community based survey to estimate the prevalence of pulmonary TB and spoligotype pattern of the Mycobacterium tuberculosis isolates in Southwest Ethiopia.

Methods

A total of 30040 adults in 10882 households were screened for pulmonary TB in Gilgel Gibe field research centre in Southwest Ethiopia. A total of 482 TB suspects were identified and smear microscopy and culture was done for 428 TB suspects. Counseling and testing for HIV/AIDS was done for all TB suspects. Spoligotyping was done to characterize the Mycobacterium tuberculosis isolates.

Results

Majority of the TB suspects were females (60.7%) and non-literates (83.6%). Using smear microscopy, a total of 5 new and 4 old cases of pulmonary TB cases were identified making the prevalence of TB 30 per 100,000. However, using the culture method, we identified 17 new cases with a prevalence of 76.1 per 100,000. There were 4.3 undiagnosed pulmonary TB cases for every TB case who was diagnosed through the passive case detection mechanism in the health facility. Eleven isolates (64.7%) belonged to the six previously known spoligotypes: T, Haarlem and Central-Asian (CAS). Six new spoligotype patterns of Mycobacterium tuberculosis, not present in the international database (SpolDB4) were identified. None of the rural residents was HIV infected and only 5 (5.5%) of the urban TB suspects were positive for HIV.

Conclusion

The prevalence of TB in the rural community of Southwest Ethiopia is low. There are large numbers of undiagnosed TB cases in the community. However, the number of sputum smear-positive cases was very low and therefore the risk of transmitting the infection to others may be limited. Active case finding through health extension workers in the community can improve the low case detection rate in Ethiopia. A large scale study on the genotyping of Mycobacterium tuberculosis in Ethiopia is crucial to understand transmission dynamics, identification of drug resistant strains and design preventive strategies.

Keywords:
Pulmonary TB; Prevalence; Spoligotype; Southwest Ethiopia