1. Centre for Viral Zoonoses, Department of Medical Virology, University of Pretoria, Pretoria 0001, South Africa
2. Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Disease of the National Health Laboratory Service, Johannesburg 2131, South Africa
3. Department of Microbiology and Infectious Diseases, Faculty of Health Sciences, University of Witwatersrand, Johannesburg 2000, South Africa