US first lady Michelle Obama is to pay official visits to South Africa and Botswana later this month to promote issues such as education, health, and wellness, the White House said last night. \"This visit ... will underscore that the United States has an important stake in the success of Africa\'s many nations and underscore the historic connections between the American people and those who live on the African continent,\" the White House said in a statement. Mrs. Obama will also promote the issues of democracy, development and \"economic opportunity\" in Africa supported by her husband, US President Barack Obama, it said