Funding for this research was provided by:
Consejo de Desarrollo Científico y Humanístico, Universidad Central de Venezuela (31920170044)
Received: 7 March 2019
Accepted: 22 July 2019
First Online: 4 September 2019
Ethics approval and consent to participate
: The study protocol was approved by the Medical Research Ethics Committee of the Northwestern Minzu University, and all participants provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.