A book detailing a culture of corruption in Kenya is making booksellers and government officials uneasy, but for different reasons. The fear of reprisals is keeping sellers from stocking it, while top officials named in the book are threatening to sue for libel. The book, “It’s Our Turn to Eat: The Story of a Kenyan Whistleblower,” by Michela Wrong, focuses on John Githongo, whom the Kenyan government hired in 2003 to head an anti-graft unit.