1. Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia.
2. Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya.
3. Division of Foodborne, Waterborne and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
4. Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.