Funding for this research was provided by:
Received: 10 July 2018
Accepted: 25 December 2018
First Online: 30 January 2019
: The study protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki as reflected in a priori approval by the institution’s human research committee. The Ethics Committee of the National Statistical Office of Senegal granted ethical approval.
: Not applicable.
: The authors declare they have no competing interests.
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