Received: 29 September 2017
Accepted: 11 January 2019
First Online: 23 January 2019
Ethics approval and consent to participate
: Ethical clearance was secured from the Ethical Review Board (IRB) of University of Gondar, Institute of Public Health. Verbal consent was obtained from each study participant and this was approved by the ethical committee.
: Not applicable
: The authors declare that they have no any competing interests.
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