男,36歲。發(fā)熱半個(gè)月。熱型不規(guī)則,伴有輕度腹瀉。血白細(xì)胞正常。肥達(dá)反應(yīng):"O"1:320,"H"1:80。副傷寒A1:80,副傷寒B1:640。外斐反應(yīng)OX191:40.臨床診斷首先考慮()