1. Gondar College of Medical Sciences, Department of Microbiology and Parasitology, Gondar, Ethiopia
2. Ethiopian Health and Nutrition Research Institute–Ethiopian Netherlands AIDS Research Project (EHNRI-ENARP), Addis Ababa, Ethiopia
3. Addis Ababa University, Department of Biology, Addis Ababa, Ethiopia
4. Municipal Health Service, Division of Public Health and Environment (GGGD), Amsterdam, the Netherlands
5. Central Laboratory of the Netherlands Red Cross Blood Transfusion Service (CLB), Amsterdam, the Netherlands