United Nations officials said bad water and sanitation are spreading deadly cholera among more than 1 million Rwandan refugees encamped near the Zairian border town of Goma. Today more than 200 infected corpses were dumped in a pit near a banana plantation. The Rwandans, most of them Hutu who fear reprisals from the victorious Rwandan Patriotic Front at home, also face mass starvation. Of the 660 tons of food officials say is needed daily, the U.N. has only managed to distribute 44 tons. Worse, almost half a million more refugees are streaming to other border towns, with 2 million more on the way. Several international relief agencies said today that only massive, concerted intervention by Western governments can avert an unprecedented disaster.