The reaction was swift and unforgiving.
Prime Minister Justin Trudeau of Canada joined a chorus of world leaders, the State Department, medical professionals and social media users who expressed outrage or puzzlement at the appointment. Appearing in Edmonton on Saturday, Mr. Trudeau told reporters that he thought the choice of Mr. Mugabe was “a bad April Fool’s joke,” according to the local news media.
Twenty-eight health organizations, including the NCD Alliance — which works with the W.H.O. and other global groups to battle noncommunicable diseases — released a statement expressing “shock” at the appointment.
Obert Gutu, a spokesman for Zimbabwe’s main opposition party, Movement for Democratic Change, said, “It is an insult.”
He added: “Mugabe trashed our health delivery system. He and his family go outside of the country for treatment in Singapore after he allowed our public hospitals to collapse.”
Under Mr. Mugabe’s authoritarian rule, critics say, the country’s health care system, like many of its public services, has suffered badly, with hospitals frequently lacking essential supplies and nurses and doctors regularly left without pay.
Hillel Neuer, the executive director of UN Watch, a human rights group, had condemned the choice and called on Dr. Tedros to reconsider, writing on Twitter: “@DrTedros I urge you to cancel your appointment of Mugabe as W.H.O. ‘good-will ambassador’ — he ruined Zimbabwe’s health.”
In a tweet on Saturday, Dr. Tedros wrote: “I’m listening. I hear your concerns. Rethinking the approach in light of WHO values.”
A spokesman for the W.H.O., Christian Lindmeier, had said that the agency’s director general was seeking broad support for its work. “Tedros has frequently talked of his determination to build a global movement to promote high-level political leadership for health,” he said.
In his statement on Sunday, Dr. Tedros said, “I remain firmly committed to working with all countries and their leaders to ensure that every one has access to the health care they need.”