Received: 21 July 2019
Accepted: 27 February 2020
First Online: 16 March 2020
Ethics approval and consent to participate
: This study received ethical approval from the London School of Hygiene & Tropical Medicine (11955/11955-1) and the Chiapas State Ministry of Health (5033/1800).
: All participants were provided informed consent before the data collection took place, through which they authorised the use of their data in an anonymised and confidential form.
: The authors declare that they have no competing interests.