Yield of household contact investigation of patients with pulmonary tuberculosis in southern Ethiopia

Mubarek A Yassin,Luis E Cuevas,Daniel G Datiko,Mohammed A Yassin,Kesetebirhan D Yirdaw

doi:10.1186/s12889-020-08879-z

Mubarek A Yassin, Luis E Cuevas + Show 3 more

Open Access

https://doi.org/10.1186/s12889-020-08879-z

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Abstract

BackgroundHousehold Contacts (HHCs) of patients with pulmonary tuberculosis (PTB) have a higher risk of developing TB. Contact investigation is recommended to reach this group and identify undiagnosed cases. In this study, we have determined the yield of contact investigation among HHCs of patients with smear-positive PTB, and estimated TB burden.MethodsWe conducted retrospective record review for the occurrence of TB among HHCs of Index PTB+ cases treated between November 2010 and April 2013 in 12 public health facilities in Boricha district. HHCs were followed up monthly and revisited between March and June 2015. Information on additional TB cases diagnosed and treated among HHCs were documented. HHCs who were diagnosed as having TB after the index cases were diagnosed and treated were considered as ‘incident cases’. Presumptive TB case was defined as those having cough for ≥2 weeks or enlarged lymph node. Diagnosis of TB among HHCs were made using smear-microscopy and/or X-rays, and clinically for Extra-pulmonary TB (EPTB).ResultsOne thousand five hundred and seventeenth HHCs of 344 index cases were visited and screened for TB and followed up for a median of 37 months. 77 (5.1% - 72 with PTB and 5 with EPTB) HHCs developed TB during 4713 person-years of follow-up with an estimated incidence of 1634 (95% CI: 1370-2043) per 100,000 person-years follow-up which is much higher than the estimated TB incidence for the general population in Ethiopia of 210/100,000. Half (41/77) of incident TB cases were diagnosed within the first year of diagnosis of the index cases and 88% (68/77) were adults (Hazard Ratio: 4.03; 95% CI: 2.00–8.12).ConclusionHHCs of index PTB+ cases have high risk of developing active TB. Long term follow-up of HHCs could help improve TB case finding depending on country contexts. Further studies on effectiveness and feasibility of the approach and integration in routine settings are needed.

Highlights

Household Contacts (HHCs) of patients with pulmonary tuberculosis (PTB) have a higher risk of developing TB
This study demonstrated that contact investigation (CI) could identify additional TB cases long after index cases were diagnosed and treated
Between 2010 and 2015, a community-based TB project implemented in the district and trained health extension workers (HEWs) who visited all households in their villages (Kebeles) and collected sputum samples from presumptive TB cases, prepared smears, fixed slides, and sent slides to nearest health facility laboratory for staining and smear microscopy

Summary

Introduction

Household Contacts (HHCs) of patients with pulmonary tuberculosis (PTB) have a higher risk of developing TB. We have determined the yield of contact investigation among HHCs of patients with smear-positive PTB, and estimated TB burden. A yield of 2500/100,000 HHCs was reported in this approach in Amhara and Oromia regions of Ethiopia where 15,527 HHCs were screened for TB While this approach identified undiagnosed cases, some of them may be prevalent cases which were not diagnosed in a timely manner and others could be new cases. The study by Zewdu et al in Amhara and Oromia regions was conducted from June–October 2014 and indicated that in this approach, of 272,441 close contacts of 47,021 index cases diagnosed 2 years before the study started, TB notification was 768/100,000 after contact investigation. We estimated additional TB cases diagnosed among HHCs of patients with smear positive pulmonary TB (PTB+) during long term follow-up

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