Risk factors and risk factor cascades for communicable disease outbreaks in complex humanitarian emergencies: A qualitative systematic review

Background: Communicable diseases are a major concern during complex humanitarian emergencies. Descriptions of risk factors for infectious disease outbreaks are often non-specific and yet not easily generalizable to similar situations. This review attempts to capture relevant evidence and explore whether it is possible to better generalize the role of risk factors and the risk factor cascades these factors may form.

Methods: A systematic search of the key databases and websites was conducted. Search terms included terms for complex humanitarian emergencies (per United Nations Office for the Coordination of Humanitarian Affairs definition) and terms for communicable diseases. Due to the types of evidence found, a thematic synthesis was conducted.

Results: 26 articles met inclusion criteria. Key contextual risk factors include crowded conditions, forced displacement, poor quality shelter, poor water, sanitation and hygiene conditions, lack of health care facilities and lack of adequate surveillance. Most identified risk factors do not relate to specific diseases, or are specific to a group of diseases such as diarrheal diseases and not to a particular disease within that group. Risk factors are often listed in general terms but are poorly evidenced, not contextualized and not considered with respect to interaction effects in individual publications. The high level of the interrelatedness of risk factors became evident, demonstrating risk factor cascades that are triggered by individual risk factors or clusters of risk factors.

Conclusions: Complex humanitarian emergencies pose a significant threat to public health. More rigorous research on the risk of communicable disease outbreaks in complex humanitarian emergencies is needed, both from a practitioner and from an academic point of view.