1. Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.
2. Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, Maryland, USA.
3. Department of Biology, Shippensburg University, Shippensburg, Pennsylvania, USA.
4. Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.