GENEVA — United Nations and international aid agencies warn that cholera is spreading in drought-stricken Somalia as hunger grips that nation and the threat of famine inches closer. The World Health Organization reports more than 21,000 cases of cholera, including 533 deaths, in Somalia since the beginning of the year. The International Federation of Red Cross and Red Crescent Societies also reports that an outbreak of the deadly disease in the self-declared autonomous region of Somaliland has killed 28 people in just the last week-and-a-half, and hospitalized nearly 170 others. Jens Laerke, spokesman for the U.N.’s Office…