Background: Working in humanitarian crisis situations is dangerous. National humanitarian staff in particular face the risk of primary and secondary trauma exposure which can lead to mental health problems. Despite this, research on the mental health of national staff is scarce, and a systematic analysis of up-to-date findings has not been undertaken yet.

FOREWORD
We are aware that in low resource settings, psychosocial wellbeing is affected by exposure
to many different sources of difficulty and distress. This might be exposure to armed
conflict that in turn directly affects mental health and psychosocial functioning. However
not all distress (including psychological trauma) is related to the conflict itself or to the
stressful conditions it so often generates. Chronic problems like poor housing and poverty
as well as more intense experiences, such as physical and sexual abuse, frightening medical

Wietse Tol and colleagues discuss some of the key challenges for implementation of new WHO guidelines for stress-related mental health disorders in low- and middle-income countries. Please see later in the article for the Editors' Summary.

In war affected populations there is often severe disruption of societal cohesion. Additionally, grief and traumatisation, along with insufficient health services and a lack of security, give rise to an increase of mental health problems. Social capital is potentially a key resource to support post conflict recovery, and is increasingly considered not merely as a resource supporting economic and social development, but also an important influence on population health. However, linkages between social capital and mental health are complex.