The United Nations children's agency is sending medical aid to the West African country of Sao Tome and Principe to combat a cholera outbreak that has infected 131 people and killed three, it said Tuesday. Most of the cases have been diagnosed in the Agua Grande district around the capital of Sao Tome. Most of the country's population lives within 10 kilometers (6 miles) of the outbreak area and is at risk of catching the deadly disease, UNICEF said. «It is extremely urgent that we get clean water and safe toilet and sanitary facilities as quickly as possibly to all affected communities,» said UNICEF official Kristian Laubjerg. UNICEF said has provided almost US$53,000 (¤41,300) worth of medication and oral rehydration salts to the twin-island nation, which is located off the West African coast in the Gulf of Guinea, AP reported. The United Nations classifies Sao Tome as one of the world's poorest countries. Nearly 20 percent of its population has no access to safe drinking water and only 9 percent have sanitary toilet facilities, UNICEF said. Cholera, a severe bacterial infection of the intestine caused by ingesting infected food or water and poor sanitation, is frequently reported in Africa. Symptoms of the disease include diarrhea and vomiting, and it can kill unless treated quickly.