Six US military planes have arrived in the Ebola hot zone with more Marines as West Africa's leaders pleaded for the world's help in dealing with 'a tragedy unforeseen in modern times.' 'Our people are dying' Sierra Leone President Ernest Bai Koroma lamented by video conference at a World Bank meeting in Washington. He said other countries are not responding fast enough while children are orphaned and infected doctors and nurses are lost to the disease. Alpha Conde of Guinea said the region's countries are in 'a very fragile situation.' 'This disease is today an international threat and deserves an