Article History
Received: 4 July 2018
Accepted: 6 June 2019
First Online: 9 July 2019
Compliance with ethical standards
: Ethics approval was obtained from the Biomedical Research Ethics Committee, University of KwaZulu-Natal number BE264/17. This article does not contain any studies with human participants performed by any of the authors.
: The authors declare that they have no conflict of interest.