The burden of tuberculosis in crisis-affected populations: a systematic review

Crises caused by armed conflict, forced population displacement, or natural disasters result in high rates of excess morbidity and mortality from infectious diseases. Many of these crises occur in areas with a substantial tuberculosis burden. We did a systematic review to summarise what is known about the burden of tuberculosis in crisis settings. We also analysed surveillance data from camps included in UN High Commissioner for Refugees (UNHCR) surveillance, and investigated the association between conflict intensity and tuberculosis notification rates at the national level with WHO data. We identified 51 reports of tuberculosis burden in populations experiencing displacement, armed conflict, or natural disaster. Notification rates and prevalence were mostly elevated; where incidence or prevalence ratios could be compared with reference populations, these ratios were 2 or higher for 11 of 15 reports. Case-fatality ratios were mostly below 10% and, with exceptions, drug-resistance levels were comparable to those of reference populations. A pattern of excess risk was noted in UNHCR-managed camp data where the rate of smear testing seemed to be consistent with functional tuberculosis programmes. National-level data suggested that conflict was associated with decreases in the notification rate of tuberculosis. More studies with strict case definitions are needed in crisis settings, especially in the acute phase, in internally displaced populations and in urban settings. Findings suggest the need for early establishment of tuberculosis services, especially in displaced populations from high-burden areas and for continued innovation and prioritisation of tuberculosis control in crisis settings.