Funding for this research was provided by:
Wellcome Trust (-)
Received: 19 February 2019
Accepted: 10 July 2019
First Online: 22 July 2019
Ethics approval and consent to participate
: Written and verbal consent were obtained from all participants. Three persons declined to take part, two of whom we replaced with two further participants. But one participant could not be replaced as there was no reserve list. Respondents were compensated with a small souvenir (cloth bag). The study was approved by the Institute for Population and Social Research Institutional Review Board, Mahidol University, with COA. No. 2016/04–035, and by the University of Oxford Tropical Research Ethics Committee, OxTREC: 31–15.
: Not Applicable.
: The authors declare that they have no competing interests<b>.</b>