He is an expert in travel and tropical medicine working in clinical medicine, surveillance and policy development and serves as a technical advisor to the Centers for Disease Control and Prevention (CDC) where he works on issues of human mobility and how it effects human health (e.g. travel medicine, refugee & immigrant health). He works extensively overseas in clinical medicine and in public health, most recently in Peru, Haiti, and in Tanzania. His research areas have included infectious disease surveillance, malaria diagnostics, neglected tropical diseases, cost evaluation of public health programs, avian influenza, strongyloidiasis and viral hepatitis.