1. The Westmead Institute for Medical Research, Faculty of Medicine, The University of Sydney, Westmead, NSW 2145, Australia
2. Faculty of Medicine, Nile University, Khartoum HJW8+2P2, Sudan
3. Centre for Infectious Diseases and Microbiology, Sydney Infectious Diseases Institute, The University of Sydney at Westmead Hospital, Westmead, NSW 2145, Australia