Received: 23 October 2017
Accepted: 8 March 2018
First Online: 13 March 2018
Ethics approval and consent to participate
: The study was approved by the Human Institutional Ethics Committee of Mizan-Tepi University, and informed consent was obtained from all participants.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.