1. Division of Occupational Medicine, Centre for Environmental and Occupational Health Research, School of Public Health and Family Medicine University of Cape Town Cape Town South Africa
2. Department of Environmental and Occupational Health, School of Public Health and Social Sciences Muhimbili University of Health and Allied Sciences Dar es Salaam Tanzania
3. Department of Environmental and Occupational Studies, Faculty of Applied Sciences Cape Peninsula University of Technology Cape Town South Africa
4. National Institute for Occupational Health National Health Laboratory Services Johannesburg South Africa
5. Department of Environmental Health, School of Health Sciences University of Johannesburg Johannesburg South Africa
6. Department of Clinical Microbiology and Infectious Diseases, School of Pathology University of the Witwatersrand Johannesburg South Africa