作者单位:US Ctr Dis Control & Prevent, Bacterial Special Pathogens Branch, Atlanta, GA USA[1]Univ Otago, Dept Math & Stat, POB 56, Dunedin 9054, New Zealand[2]Univ Otago, Dept Prevent & Social Med, Dunedin, New Zealand[3]Univ Otago, Ctr Int Hlth, Dunedin, New Zealand[4]Duke Univ, Div Infect Dis, Durham, NC USA[5]