 During the Bangladesh's war for independence he led the effort by the Johns Hopkins Center that demonstrated the dramatic life-saving effectiveness of oral rehydration therapy when cholera broke out in 1971 among refugees from East Bengal (now Bangladesh) who had sought asylum in West Bengal.In the mid-1980s and early 1990s, he was a medical officer in the Diarrheal Disease Control Programme of the WHO.Later in the 1990s, he served as the Director of Clinical Research at the International Centre for Diarrhoeal Disease Research (ICDDR,B), Bangladesh.