Dr. Callahan is Associate Physician at Massachusetts General Hospital and Harvard Medical School. He is board certified in internal medicine, infectious diseases and tropical medicine and is a licensed Command Physician with Rescue Medicine, an international medical evacuation service provider which has accrued an expatriate risk actuary of 39000 expatriate life-years, the most comprehensive database in health risk assessment. Dr. Callahan entered federal service as program director for the Defense Advanced Research Projects Agency (DARPA), where he managed 7 remote medical care and therapeutics programs in excess of $220M over eight years, resulting in novel therapeutics for altitude acclimatization, emergency anti-infectives, and mass casualty care medicine. Dr. Callahan's federal responsibilities include serving the Office of the President and National Security Counsel of two administrations and execution of health threat assessments from the bedside of foreign referral hospitals under the White Coat Diplomacy and federal interagency cooperative programs for countering pandemic influenza and highly dangerous pathogens. Since 1998, he has deployed to over 17 UN disaster and disease outbreak operations including the 2003 SARS-CoV, 2004 Marburg, 2001-2012 Ebola outbreaks, and 3 H5N1 clusters. Dr. Callahan is a guest professor of medicine with teaching attending privileges at national teaching hospitals in Bangkok, Beijing a, d Jakarta and is currently executing 3 IRB trials for highly dangerous pathogen care in Nigeria, DRC, and Indonesia. He has been a member of the WorldAware medical advisory board since 2003.