• Amsalu Bekele Addis Ababa University college of health Sciences
  • Senait Ashenafi Departement of Pathology, Addis Ababa University and Karolinska Institute, Sweden
  • Getachew Aderay Department of Internal Medicine, School of Medicine, Addis Ababa University, Ethiopia
  • Getachew Assefa Department of Radiology, Addis Ababa University, Ethiopia
  • Abraham Aseffa Armauer Hansen Research Institute (AHRI), Ethiopia
  • Jan Anderssen Karolinska Institute, Sweden
  • Susanna Brighenti Karolinska Institute, Sweden


Background: One-third of the world population is infected with mycobacterium tuberculosis. Most people exposed to mycobacterium tuberculosis showed no evidence of active disease. About 5-10% of latent tuberculosis infection without HIV will progress to developed active tuberculosis in their lifetimes. This study was conducted to determine the magnitude of Latent TB among the adult population at a teaching and referral Hospital in Ethiopia.

Methods: This study was conducted at the Chest clinic of Tikur Anbessa Specialized Hospital during 2010-2013.The study was a cross-sectional study conducted among healthy adults after informed consent was obtained from each individual. Tuberculin skin test and Interferon Gamma whole blood assay (Quantiferon-Tuberculosis-Gold) was performed using Enzyme linked Immuno-sorbent Assay. Average CD4, CD8, CD3 and CD4:CD8 ratio was determined for all study participants. 

Results:From a total of 70 healthy adults tested for latent tuberculosis infection using Quantiferon Gold,45(64%) tested positiveand 25 (36%) were negative for latent tuberculosis infection. From the sixty six healthy individuals who were tested using tuberculin skin test for latent tuberculosis infection, 42 (62%) individuals were Tuberculin skin test positive and 25 (38%) individuals were Tuberculin skin test negative.  Average CD4, CD8, CD3 and CD4:CD8 ratio was 748, 598, 1401 and 1.4, respectively.

Conclusions: The magnitude of latent tuberculosis infection was high in this study, which reflects existing high prevalence of tuberculosis.Tuberculin skin test and Quantiferon-Tuberculosis-Goldassay show similar efficacy for the diagnosis of latent tuberculosis infection in healthy Ethiopian adults.  The absolute CD4 T-cell counts of healthy HIV-negative Ethiopian's are considerably lower than other countries.

Key Words: Latent tuberculosis ,Chest clinic , adult population , TAH


Author Biography

Amsalu Bekele, Addis Ababa University college of health Sciences

Assistant professor of Medicine,Department of Internal Medicine,college of health sciences,AAU



Philana Ling Lin and JoAnne L. Flynn. Understanding Latent Tuberculosis: A Moving Target. Journal of Immunology, 2010, 185:15–22.

Latent Tuberculosis Infection (LTBI) Targeted Testing and Treatment. Prepared November 2000, Revised April 2009 Medical Advisory Committee for the Elimination of Tuberculosis (MACET)

Dye C, Scheele S, Dolin P, Pathania V, Raviglione MC. Consensus statement: global burden of tuberculosis: estimated incidence, prevalence, and mortality by country. WHO Global Surveillance and Monitoring Project. JAMA 1999;282:677–86.

American Thoracic Society (ATS) and the Centers for Disease Control and Prevention (CDC). Targeted tuberculin testing and treatment of latent tuberculosis infection. Am J RespirCrit Care Med 2000;161:S221–47.

Fine PE, Sterne JA, Ponnighaus JM, Rees RJ. Delayed-type hypersensitivity, mycobacterial vaccines and protective immunity. Lancet 1994;344:1245–9.

Fine PE, Bruce J, Ponnighaus JM, Nkhosa P, Harawa A, Vynnycky E. Tuberculin sensitivity: conversions and reversions in a rural African population. Int J Tuberc Lung Dis 1999; 3:962–

Huebner RE, Schein MF, Bass JB Jr. The tuberculin skin test. Clin Infect Dis 1993; 17:968–75

Federal Democratic Republic of Ethiopia Ministry of Health. Annual TB Bulletin 2013 Volume 5,2013.An extract of five years TB,TB/HIV and Leprosy Control Program Analysis (EFY 2000-2005)

Zaharani AL, Al Jahdali K, Menzies D. Does size matters? Utility of size of tuberculin reactions for the diagnosis of mycobacterial disease. Am J Resp Crit Care Med 2000; 162:1419-22

Dheda K, Chang JS, Kim LU, Huggett JF; Johnson MA et al. Interferon gamma assay for tuberculosis. Lancet Infect Dis 2005;5:324-25

Lalvani A, Richeldi L, Kunst H. Interferon gamma assays for tuberculosis. Lancet Infec Dis 2005;5:322-24.

Pai M, Dheda K, Cunningham J et al. T-cell Assays for the diagnosis of latent tuberculosis infection: Moving the research agenda forward. Lancet Infect Dis 20007;7:428-438.

Diagnostic Standards and Classification of Tuberculosis in Adults and Children. This official statement of the American Thoracic Society and the Centers for Disease Control and Prevention was adopted by the ATS Board of Directors, July 1999. Am J Resp Crit Care Med 2000; 161:1376-95.

Latent Tuberculosis Infection: A Guide for Primary Health Care Providers U.S. Department of Health and Human Services Centers for Disease Control and Prevention National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention Division of Tuberculosis Elimination Atlanta, Georgia Developed in partnership with the New Jersey Medical School Global Tuberculosis Institute 2013.

Legesse M, Ameni G, Mamo M, Medhin G, Bjuneand G, Abebe F. Association of the level of IFN-γ produced by T cells in response to Mycobacterium tuberculosis-specific antigens with the size of skin test indurations among individuals with latent tuberculosis in a highly tuberculosis-endemic setting. International Immunology, Vol. 24, No. 2, pp. 71–78 doi:10.1093/intimm/dxr102. Advance Access publication 31 January 2012.

Legesse, Ameni G, Mamo G, Medhin G, Bjune G, AbebeF. Community-based cross-sectional survey of latent tuberculosis infection in Afar pastoralists, Ethiopia, using QuantiFERON-TB Gold In-Tube and tuberculin skin test. Legesse et al. BMC Infectious Diseases 2011, 11:89

Dagnew A, Hussein J, Abebe M, et al. Diagnosis of latent tuberculosis infection in healthy young adults in a country with high tuberculosis burden and BCG vaccination at birth. Dagnew et al. BMC Research Notes 2012, 5:415. 0500/5/415.

Tsegaye A, Messele T, Tilahun T, et al. Immunohematological Reference Ranges for Adult Ethiopians. ClinDiagn Lab Immunol 1999; 6(3):410–14.

Clinical and diagnostic laboratory immunology, 1071-412X/99/$04.0010 May 1999, p. 410–414 Vol. 6, No. 3 Received 10 August 1998/Returned for modification 2 September 1998/Accepted 19 January 1999.

Shakak AO, Khalil EAG, Musa AM, et al. Possible risk factors of progression to overt disease among individuals with latent tuberculosis infection in the Sudan. IJCR 2013, 5:1107–110.

Ferebee SH: Controlled chemoprophylaxis trials in tuberculosis. A general review. Bibl Tuberc 1970, 26:28–106.

Sharma SK, Mohanan S, Sharma A: Relevance of latent TB infection in areas of high TB prevalence. Chest 2012, 142:761–73.

Machado A, Emodi K, Takenami I, et al. Riley LW: Analysis of discordance between the tuberculin skin test and the interferon-gamma release assay. IJTLD 2009, 13:446–53.

Franken WPJ, Timmermans JF, Prins C, Slootman EJ, Dreverman J, Bruins H, Van Dissel JT, Arend SM: Comparison of Mantouxand QuantiFERON TB Gold Tests for Diagnosis of Latent Tuberculosis Infection in Army Personnel. J Clin Vac Immunol 2007, 14:477–480.

Sharma SK, Mohanan S, Sharma A: Relevance of latent TB infection in areas of high TB prevalence. Chest 2012, 142:761–73.

Lewinsohn DA, Zalwango S, Stein CM et al. Whole blood interferongamma responses to mycobacterium tuberculosis antigens in young household contacts of persons with tuberculosis in Uganda. PLoS ONE 2008, 3:e3407.

Diel R, Loddenkemper R, Neinhaus A: Predictive value of interferon-γ release assays and tuberculin skin testing for progression from latent TB infection to disease state: a meta-analysis. Chest 2012, 142:63–75. Doi: 10.1378/chest.11-3157.

Diel R, Goletti D, Ferrara G, Bothamley G, et al. Interferon-γ release assays for the diagnosis of latent Mycobacterium tuberculosis infection: a systematic review and meta-analysis. EurResp J 2011, 37:88–99.

Herrera V, Perry S, Parsonnet J, Banaei N: Clinical application and limitations of interferon-γ release assays for the diagnosis of latent tuberculosis infection. Clin Infect Dis 2011, 52:1031–37.

Sester M, Sotgiu G, Lange C, Giehl C, et al. Interferon-γ release assays for the diagnosis of active tuberculosis: a systematic review and meta-analysis.Eur Resp J 2011, 37:100–111.

Brock I, Weldingh K, Lillebaek T, Follmann F, Andersen P: Comparison of a new specific blood test and the skin test in tuberculosis contacts. Am J Resp Crit Care Med 2004, 170:65–9.

Carvalho AC, Pezzoli MC, El-Hamad I, et al. QuantiFERON-TB Gold test in the identification of latent tuberculosis infection in immigrants. J Infect 2007, 55:164–8.

Diel R, Nienhaus A, Lange C, Meywald-Walter K, and Forssbohm M, Schaberg T: Tuberculosis contact investigation with a new, specific blood test in a low-incidence population containing a high proportion of BCGvaccinated persons. Resp Res 2006, 7:77.

Poorhasan A, Haghdoost M, Mashrabi O: Comparison of tuberculin skin test and interferon gamma assay for the diagnosis latent tuberculosis. Am J Infect Dis 2010, 2010(6):50–53.

Bellete B, Coberly J, Barnes GL, et al. Evaluation of a whole-blood interferon-gamma release assay for the detection of Mycobacterium tuberculosis infection in study populations. Clin Infect Dis 2002, 34:1449–56.






Original Article