[1] Army Malaria Inst, Brisbane, Qld 4051, Australia
[2] Walter Reed Army Inst Res, Silver Spring, MD USA
[3] Univ Alabama, Birmingham, AL USA
[4] Toronto Hosp, Toronto, ON M5T 2S8, Canada
[5] London Sch Hyg & Trop Med, London WC1, England
[6] Univ Zurich, WHO, Collaborating Ctr Travelers Hlth, Zurich, Switzerland