1. Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, Maryland
2. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
3. Amazonic Center for Research and Control of Tropical Diseases, Puerto Ayacucho, Venezuela
4. Instituto de Medicina Tropical, Universidad Central de Venezuela, Caracas, Venezuela
5. Venezuelan Institute for Scientific Research, Caracas, Venezuela
6. Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, New Jersey
7. Department of Anthropology, Rutgers University, New Brunswick, New Jersey