1 Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
2 Adama Science and Technology University, Adama, Ethiopia.
3 University of Notre Dame, Notre Dame, IN, USA.
4 Armauer Hansen Research Institute, Addis Ababa, Ethiopia; London School of Hygiene and Tropical Medicine, London, UK. Electronic address: fitsum.girma@ahri.gov.et.