BLANTYRE, Malawi (AP) — The southern African nation of Malawi began a cholera vaccination rollout this week in a bid to stem the threat of the disease that kills tens of thousands of people globally each year. Cholera is avoidable when there is access to clean water and largely treatable with rehydration medication, and there are effective vaccines. Malawi is one of several countries in Africa that face the perennial threat of cholera , and that’s been exacerbated this year by unusually heavy