No outbreak of epidemic has been spotted so far in the quake zone in China's northwestern Qinghai Province, said Chen Xianyi, director of the Health Ministry's disease prevention and control bureau, Friday at a press conference. In natural disasters like this, the health authority's major tasks include treatment of the injured, epidemic prevention, and giving psychological aid to the needed in the quake zone to sustain social stability, Chen said. The health authority would make special efforts to ensure clean drinking water, food and environment in its epidemic prevention work, and at the same time focus on prevention in key region, on key diseases andey groups of people, according to Chen. The ministry has sent experts to the quake zone to give guidance and support to help their local bureaus to offer psychological aid to local residents. A 7.1 magnitude earthquake hit Yushu in Qinghai Wednesday morning and has left 791 dead so far. 