Anne von Gottberg1, Graeme Meintjes2. 1. Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Private Bag X4, Johannesburg 2131, South Africa; School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; Department of Pathology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa. Electronic address: annev@nicd.ac.za. 2. Wellcome Centre for Infectious Diseases Research in Africa, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa; Department of Medicine, University of Cape Town, Cape Town, South Africa.