In the 1980s he was responsible for leading WHO's international collaborative study on breast feeding and the impact of breast-milk substitutes on infant and maternal health; he then organised the International Code of Marketing of Breast-milk Substitutes which today guides the infant food industry's role in this domain of health.
On his return from Bosnia he joined the International Centre for Migration, Health and Development (ICMHD), a Swiss-based research and training organisation.
In 2002-2003 he headed two health evaluation missions for the United Nations in the occupied Palestinian territories and Iraq.
In 2014, he was awarded an Honorary Doctor of Science by the Glasgow Caledonian University for his contribution to global health and academic research.
He is a specialist on health issues of migrants and refugees and also has worked extensively on HIV prevention programmes with uniformed services and peacekeeping forces.