Professor Woo has been a faculty member at the University of Guelph (UoG) since 1974. He was also Director, Axelrod Institute of Ichthyology, and in 2005 UoG Senate elected him University Professor Emeritus. Prior to 1974 he was MRC Postdoctoral Fellow and Ballard Fellow, UoG; FAO Andre Mayer Research Fellow, East African Trypanosomiasis Research Organization and Serengeti Research Institute; and IDRC Consultant/Scientist, Nigerian Institute for Trypanosomiasis Research.
His other appointments (1985-2010) include as NUS Visiting Research Professor, National University of Singapore, and as short-term Visiting Professor/Scientist at 16 Universities/Institutes in Africa, Asia, Europe and South America.
Patrick was Plenary/Symposium speaker at 44 conferences, recipient of The Robert Wardle Award, and elected Fellow, The Royal Society of Tropical Medicine and Hygiene. He is editor-in-chief of a journal, member of three editorial boards; and has published 194 scientific papers, 19 reviews in conference proceedings, 15 book chapters, and eight books.