Text and Data Mining valid from 2019-02-28
Received: 15 July 2018
Accepted: 20 February 2019
First Online: 28 February 2019
Ethics approval and consent to participate
: This study was approved by the ethics board of each hospital and by the Chadian Ministry of Public Health (N<sup>o</sup> 676/PR/PM/MSP/SE/SG/DRGP/DRH/SGF/16). Informed written consent was obtained from all subjects and from at least one parent for each child before enrolment in the study.
: Not applicable.
: The authors declare that they have no competing interests.
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