The mental health needs of people affected by emergencies are significant, but often overlooked by health-care providers. The world is facing an unprecedented number of humanitarian emergencies arising from conflict and disasters. In 2014, nearly 60 million people were forcibly displaced due to conflict, the highest number on record. Climatic and geological hazards continue to take their toll, as seen recently following the devastating earthquake in Nepal, cyclone in Vanuatu and flooding in China, Malawi and Myanmar.

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.