Daniel Mekonnen ^1, 2*&, Awoke Derbie ^1,3, Andargachew Abeje⁴, Abebe Shumet⁵, Endalkachew Nibret^2,6, Fantahun Biadglegne¹, Abaineh Munshae^2,6, Kidist Bobosha⁷, Liya Wassie⁷, Stefan Berg⁸, Abraham Aseffa^7&

¹Department of Medical Microbiology Immunology and Parasitology, College of Medicine and Health Sciences, Bahir Dar University, Ethiopia.²Biotechnology Research Institute, Bahir Dar University, Bahir Dar, Ethiopia. ³ The Centre for Innovative Drug Development and Therapeutic Trials for Africa (CDT-Africa), Addis Ababa University, Ethiopia. ⁴ Geospatial data and Technology center, Bahir Dar University, Bahir Dar, Ethiopia.

⁵Amhara Regional State Health Bureau, Felege Hiwot Referal Hospital, Bahir Dar, Ethiopia. ⁶Department of Biology, Bahir Dar University, Bahir Dar, Ethiopia. ⁷Armauer Hansen Research Institute, Addis Ababa, Ethiopia.⁸Animal and Plant Health Agency, Weybridge, the United Kingdom.

*Corresponding Author: Email: nigusdaniel@gmail.com (DM)

^&These authors contributed equally to this work

Abstract

Introduction: The WHO African region has the highest TB morbidity and mortality rates, accounting for most (23/30) of the high TB/HIV burden countries in the world. The rather slow decline in TB control in Africa can only be accelerated if the epidemiology of tuberculous lymphadenitis (TBLN) is better understood. Tuberculous lymphadenitis is the most frequent form of extra-pulmonary TB and accounts for a considerable proportion of all TB cases. Investigation into its epidemiology has however been neglected due to the high emphasis to pulmonary TB form as a source of transmission. We conducted a systematic review of the literature on the epidemiology of TBLN in Africa.

Methods: Any article that characterized TBLN with respect to demographic, exposure and clinical variables was included. The search for original research articles was restricted to epidemiological work conducted in African countries, published in peer reviewed journals in the English language irrespective of publication year. The articles were retrieved from the electronic database of PubMed, Scopus, Cochrane library and Lens.org. Random effect pooled prevalence with 95% CI was computed based on Dersimonian and Laird method. To stabilize the variance, Freeman-Tukey double arcsine root transformation was done. The data were analyzed using MetaXL and Stata 14.

Results: Of the total 833 articles retrieved; twenty-eight were included in quantitative analysis. Tuberculous lymphadenitis data were available from 12 African countries; of which, majority were from eastern Africa. A total of 6746 TBLN cases were identified. The majority of the cases, 4762 (70.6%) were from Ethiopia.  Over 77% and 88% of identified TBLN were cervical in type and naïve to TB drugs. Among TBLN cases, 53% were female, 68% were in the age range of 15-44 years, 52% had a history of livestock exposure, 46% had a history of consuming raw milk/meat and 24% reported BCG vaccination. The proportion of HIV co-infection among TBLN cases was much lower in Ethiopia (21%) than in other African countries (52%). Fever was recorded in 45%, night sweating in 55%, weight loss in 62% and cough for longer than two weeks in 49% of the TBLN cases.

Conclusion and recommendations: This review is the first comprehensive meta-analysis that reported pooled prevalence estimate of key demographic, exposure and clinical variables of TBLN. TBLN was more common in females and the high prevalence of TBLN in Ethiopia did not show directional correlation with HIV. A meta-analysis of intervention and observational studies is warranted to better define the risk factors driving TBLN in Africa.

Key words: Tuberculous Lymphadenitis, Epidemiology, Africa, systematic review and meta-analysis