Table 1.
Main characteristics of national TB prevalence surveys completed in Africa, 2008-2016
| Country and year |
Residency criteria | Geographical area excluded† |
Number of clusters |
Stratified sampling |
Planned sample size |
Screening strategy¶ |
Diagnostic tests |
Duration of field operations (months) |
|||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Symptoms interview | Chest X-ray | Smear | Culture | Xpert MTB/RIF | |||||||
| Ethiopia 2010-2011 | Permanent residents who stayed in the household at least one night during the 14 days prior to the census day. Temporary visitors who stayed in the household at least 14 days prior to the census day. | 37/810 woredas excluded from the sampling frame due to security and logistical challenges. | 85 | Urban/ Rural/ Pastoralist | 46 514 | Cough 2 weeks or more | Lung abnormality‡‡ | 2 FM | 1 LJ | No | 9 |
| Gambia 2012 | Residents who spent at least one night in the household in the last 4 weeks before the census. Visitors who arrived in the household 4 weeks or more before the census. | None | 80 | No | 55 281 | (i) Cough 2 weeks or more (ii) Any participant with a cough lasting <2 weeks and 2 or more other symptoms (iii) Any participant without a cough AND 3 or more other symptoms†† | Abnormal and suggestive of TB for any abnormality in lung field or mediastinum‡‡ | 2 FM | 2 MGIT | No | 14 |
| Ghana 2013 | Residents who have not been away for 2 weeks or more. | None | 98 | Urban/Rural | 64 000 | Cough 2 weeks or more | Lung abnormality‡‡ | 2 ZN§§ | 2 MGIT | Smear-positive or contaminated cultures | 10 |
| Kenya 2015-2016 | Residents who lived in the household for a minimum of 30 consecutive days prior to the census. | One cluster excluded due to security issues | 99‡ | Urban/Rural | 72 000 | Cough 2 weeks or more | Lung abnormality‡‡ | 2 FM | 2 LJ | At least one Xpert test for all participants who screened positive | 12 |
| Malawi 2013 | Residents who spent at least 14 days in the household before the census. | None | 74 | Urban/Semi-urban/Rural | 37 200 | Any symptom for 7 days or longer: cough, cough with sputum, blood stained sputum, chest pain, body weight loss, night sweat, fatigue/malaise, fever, shortness of breath | Lung abnormality | 2 FM¶¶ | 2 LJ | Smear-positive or contaminated cultures | 11 |
| Nigeria 2012 | Slept in the household for 14 days or more. | Three clusters replaced due to security issues | 70 | Zonal [6] | 49 000 | Cough 2 weeks or more | Lung abnormality | 2 ZN | 2 LJ | No | 9 |
| Rwanda 2012 | Residents who lived in the household for at least 1 month prior to interview. | None | 73 | No | 44 500 | Cough (any duration) | Lung abnormality | 2 FM | 2 LJ | No | 10 |
| Sudan 2013-2014 | Household resident or visitor for at least 3 weeks. | Four clusters were excluded due to security issues | 109§ | Urban/Rural (Nomadic) | 91 131 | Cough 2 weeks or more; currently on TB treatment | Lung abnormality‡‡ | 2 FM | 2 Ogawa | No | 12 |
| Tanzania 2012 | A person having slept for the last 2 weeks in the household | None | 62 | Urban/Rural/Semi-urban/Zanzibar | 46 792 | Cough 2 weeks or more, haemoptysis, fever for more than 2 weeks, weight loss, and excessive sweating | Any abnormality in the lung fields or mediastinum | 3 FM | 1 LJ | No (Smear-positive slides examined retrospectively) | 11 |
| Uganda 2014-2015 | Individuals who have resided in the household in the survey cluster for at least 14 days before the census day. | None | 70 | Urban/Rural | 40 180 | Cough 2 weeks or more | Lung abnormality‡‡ | 2 ZN | 2 LJ | Smear-positive or contaminated cultures | 10 |
| Zambia 2013-2014 | Individuals who have slept in the household in the previous 24 h prior to census. | None | 66 | Urban/Rural | 54 400 | Cough or fever or chest pains for 2 weeks or more | Lung abnormality or chest X-ray indeterminate‡‡ | 2 ZN | 2 MGIT | Smear-positive or contaminated cultures | 11 |
| Zimbabwe 2014 | Permanent residents who had spent a night at the household. Visitors who were residing in the selected cluster for 14 days or more before the survey. | Two clusters were replaced due to logistical issues. | 75 | Urban/Rural | 44 951 | Cough of any duration, drenching night sweats, and/or haemoptysis | Lung abnormality‡‡ | 2 FM | 2 MGIT | Smear-positive or contaminated cultures | 12 |
C, Conventional radiology; CXR, Chest X-ray; DR, Digital radiology; FM, Fluorescence microscopy; LJ, Löwenstein-Jensen; MGIT, Mycobacterial growth indicator tube; MOH, Ministry of Health; N/A, Not applicable; NTP, National TB Programme; ZN, Ziehl-Neelsen stain.
Although some surveys excluded certain geographical areas from their sampling frames, we included national surveys when most populations were covered.
In Kenya, 1 cluster was excluded from the original 100.
In Sudan, 5 clusters were excluded from the original 114; one for protocol violation and four for security reasons.
Criteria for eligibility of sputum examination.
In Gambia, other symptoms included chest pain, fever, haemoptysis, night sweats, shortness of breath, loss appetite and weight loss.
Other criteria were used especially if a participant was exempt or refused to have a chest X-ray. Please see supplementary file (Text S2) for details.
In Ghana, Zield-Neelsen smears used the concentrated method
In Malawi, FM smears used the concentrated method.