1. Department of Preventive and Social Medicine, University of Port Harcourt, Port Harcourt, Nigeria 500102
2. Africa Centre for Public Health and Toxicological Research, University of Port Harcourt, Port Harcourt, Nigeria 500102
3. Department of Paediatrics, Rivers State University Teaching Hospital, Port Harcourt, Nigeria
4. Department of Paediatrics and Child Health, University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria