1. Papua New Guinea Institute of Medical Research, Madang, Madang Province, Papua New Guinea;
2. Department of Pediatrics, Modilon Hospital, Madang, Madang Province, Papua New Guinea;
3. Faculty of Health and Medical Sciences, University of Western Australia, Fremantle Hospital, Fremantle, Australia;
4. Faculty of Health and Medical Sciences, Fiona Stanley Hospital, Harry Perkins Institute, University of Western Australia, Murdoch, Australia