In 1976 villagers in a remote settlement on the Ebola River in northern Zaire began falling prey to a mysterious sickness. Fever was followed by haemorrhage in multiple sites in the body and, in 90 per cent of cases, by death. Panic set in and the Government of President Mobutu was offered help by the Centres for Disease Control and Prevention in the US.

While the two experts it dispatched were discussing the virus on the flight from Geneva to Kinshasa, a fellow passenger overheard them and introduced himself. Bill Close was then nearing the end of 16 years’ work as an American doctor in Zaire, ten of them as Mobutu’s personal physician. His energy, his readiness to accept challenges and his pull with the dictatorial Mobutu were to prove vital in stemming what the World Health Organisation called its gravest emergency in 30 years.

Using military aircraft, Close was able to get the medical team and equipment flown speedily into the area and ferried between sites of the outbreak in the dense rainforest. About 430 people had died, but the imposition of quarantine controlled the epidemic. Moreover, the blood samples taken later proved an important resource for those investigating the onset of another unknown condition: Aids.

Close had first gone to Zaire, then the Belgian Congo, six weeks before it gained independence in 1960. He was then working for Moral Rearmament (MRA), the evangelical movement that aimed to offer the young a third way between consumerism and communism. When increasing violence led much of the white population to flee, including the doctors in the capital’s main hospital, Close found in the exercise of his medical skills a more practical outlet for his idealism than the good intentions of MRA.

Soon he was undertaking 350 operations a month, often with the most rudimentary tools. Cranial surgery was performed with a carpenter’s drill. Yet such was his steadfastness of purpose that by the late 1960s, when he was running the hospital, it was able each day, despite its slender resources, to welcome 170 babies into the world, to treat 4,000 outpatients and to keep two miles of corridors clean.

Congo stretches from Sudan to Angola and encompasses 230 dialects. Close’s rare ability to get things done in its vastness was in part due to his privileged access to its leader. This began when he circumcised Mobutu’s eldest son — a stressful experience for both parties as he had never carried out the procedure before. He then saved the President’s great-aunt from choking on a fishbone. Mobutu appointed him chief medical officer to the army, and later his private doctor.

At first Close felt that Mobutu shared his progressive hopes for Zaire, and was impressed by his easy charm, thoughtfulness and charisma — his presence alone was sufficient to quell a potential mutiny. Theirs became a genuine friendship, based around games of draughts and a shared aversion to pomposity and formality.

Mobutu had yet to become a corrupt autocrat, and even when he did Close understood something of his motivation, and was later able to write about it with insight, albeit without sympathy. Insecure since birth — he never knew who his father was and his very name meant “low as the dust” — Mobutu ultimately succumbed to the African expectation that power entailed providing for one’s family, not for the masses.

By the early 1970s, when Mobutu was starting to mask personal enrichment with nationalist rhetoric, Close had begun to tire of having to attend him on his many international trips and found himself listened to less often. Mobutu was also showing signs of poor health and Close feared the consequences should his patient die.

For many years, too, the demands of Close’s work had put a strain on relations with his family, including his daughter, Glenn, an aspiring actress, and he had relied on his wife, Tine, to hold them together. Accordingly, in 1976 they settled in Wyoming, where he became the sole doctor for the least populated area of the United States.

The younger of twin boys, William Taliaferro Close was born in Greenwich, Connecticut, in 1924. His father ran the American Hospital in Paris, and Bill grew up speaking French, which proved invaluable in Africa. He was sent to schools in England — Summer Fields in Oxford and Harrow — before losing his British accent at St Paul’s, Concord, New Hampshire.

After two years at Harvard, he was married to Bettine Morris at 18, and promptly volunteered for wartime training as a pilot with the Army Air Corps. In 1944 he flew out casualties from the Battle of the Bulge. He then showed characteristic determination in being accepted for training as a surgeon in New York despite lacking the requisite academic grades.

Though he feared he could sometimes appear buttoned up to his family, his patients much appreciated Close’s warmth, experience and dedication. This was reflected in his continuing to make house calls long after most doctors had given these up, and in his practice of sitting with a family while a patient was slipping away, something he had learnt in Africa.

He returned to Zaire in 1994 at Mobutu’s request to oversee a renovation of the Mama Yemo Hospital in Kinshasa, and last met him in 1996, shortly before the dying dictator was ousted by Joseph Kabila. Close published several memoirs, including Beyond the Storm (2007), about his time in Zaire.

He is survived by his wife, a son and three daughters. Another son died in infancy.

Bill Close, doctor, was born on June 7, 1924. He died on January 15, 2009, aged 84