Funding for this research was provided by:
Vetenskapsrådet (642-2013-8019, 621-2014-5211)
National Research Foundation (77256)
Knut och Alice Wallenbergs Stiftelse (Mattias Jakobsson)
Received: 19 December 2019
Accepted: 31 January 2020
First Online: 24 February 2020
Ethics approval and consent to participate
: Ethical clearance for this study was obtained from the ethics committee from the Natural and Agricultural Science of the University of Pretoria EC11912-065. All subjects were given a study information sheet and gave their written informed consent for the collection of samples and subsequent analysis.
: The authors declare that they have no competing interests.