Sheik Umar Khan, who was credited with treating more than 100 patients, was infected with Ebola this month and had been moved to a treatment ward run by medical charity Medecins Sans Frontieres in the far north of the country.
It comes as Nigerian health officials are in the process of trying to trace 30,000 people thought to have come into contact directly or indirectly with a Liberian Ebola victim.
Patrick Sawyer, a consultant for Liberia's Finance Ministry, died on Friday after arriving at Lagos airport on June 20, having vomited and suffered diarrhoea on two flights.
The 40-year-old U.S. citizen had been to the funeral of his sister, who also died from the disease.
He was put in isolation at the First Consultants Hospital in Obalende, one of the most crowded parts of the
