1. Medicine and Health Science College, Hawassa University, P.O. Box 1560, Hawassa, Ethiopia
2. Aklilu Lemma Institute of Pathobiology, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia
3. School of Pharmacy, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia