[1] Univ Pretoria, Dept Med Microbiol, Div Clin Pathol, ZA-0002 Pretoria, South Africa
[2] Natl Hlth Lab Serv, Tshwane Acad Div, Pretoria, South Africa
[3] Univ Pretoria, Dept Haematol, ZA-0002 Pretoria, South Africa
[4] Kalafong Hosp, Dept Internal Med, Kalafong, South Africa