Causes of non-malarial fever in Laos: a prospective study by Mayxay, M, Castonguay-Vanier, J, Chansamouth, V, Dubot-Pérès, A, Paris, DH, Phetsouvanh, R, Tangkhabuanbutra, J, Douangdala, P, Inthalath, S, Souvannasing, P, Slesak, G, Tongyoo, N, Chanthongthip, A, Panyanouvong, P, Sibounheuang, B, Phommasone, K, Dohnt, M, Phonekeo, D, Hongvanthong, B, Xayadeth, S, Ketmayoon, P, Blacksell, SD, Moore, CE, Craig, SB, Burns, M-A, von Sonnenburg, F, Corwin, A, de Lamballerie, X, González, IJ, Christophel, EM, Cawthorne, A, Bell, D, Newton, PN