The Nepali scientist using mathematics to understand how diseases spread 

Before he was modelling viruses on computers in the United States, Dr Naveen Vaidya was a boy in Sindhuli studying under the faint light of a kerosene lamp.

His childhood was marked by loss. His father, a government employee, died when Vaidya was still young, leaving his mother as the family’s only support. She worked in the fields and took on small jobs to educate her children.