1. Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
2. Division of Tropical Medicine, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
3. Department of Environmental and Occupational Health, University of Nevada Las Vegas, Las Vegas, Nevada, USA
4. Department of Laboratory Medicine, University of California San Francisco School of Medicine, San Francisco, California, USA
5. Department of Epidemiology and Biostatistics, University of California San Francisco School of Medicine, San Francisco, California, USA