Received: 29 July 2018
Accepted: 15 February 2019
First Online: 21 February 2019
Ethics approval and consent to participate
: Ethical approval was granted by the National Ethics Committee for Health Research of the Ministry of Health of Cambodia (approval No. 38SNECHR). Written informed consent was obtained from the parents and verbal assent was obtained from the children prior to data collection.
: Not applicable.
: The authors declare that they have no competing interests.
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