[2] He has completed his one-year medical internship at Base Hospital, Nawalapitiya, under surgeon WG Jayawickrama and pediatrician Mohomad Nilam Jiffry.

Jayasumana was a pioneering academic staff member of the Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka.

He has done extensive research on drinking water, occupational exposure to pesticides, and their association with chronic kidney disease, which highly prevalent in rural farming communities.

Jayasumana's contribution to the field of nephrology and toxicology with his postdoctoral supervisor Professor Marc de Broe of the University of Antwerp, Belgium is highly recognised on many international platforms.

As a student union leader, he was actively involved with Sri Lankan politics in the presidential election held on 2005.

Jayasumana contested the parliamentary election held in August 2020 for the Anuradhapura electorate in North Central Province and secured 133,980,[9] a recorded number of preferential votes.

In 2014, he married Ruwi Jayasumana, sales executive of a leading private sector business firm, later turned into an entrepreneur.