1. Bacteriology Department, Naval Medical Research Unit-6 (NAMRU-6), Lima, Peru;
2. Facultad de Ciencias Biológicas, Universidad Nacional Mayor de San Marcos, Lima, Peru;
3. U.S. National Medical Research Center, Singapore;
4. Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, Maryland;
5. Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia