Leaders from around the world are paying tribute to former U.S. President Jimmy Carter, who died Sunday at the age of 100, including South Africa’s President Cyril Ramaphosa, who recalled Carter as “an outspoken critic of the apartheid state.” Former President Carter was touring villages in Ghana during the late 1980s when he first encountered people with Guinea worm disease, and he led the fight to eliminate it. The situation remains tense in much of Kenya following fresh protests by young adults, who are angry over alleged extrajudicial abductions of government critics.