1. Ministry of Health Khartoum State, P.O. Box 1517, Khartoum, Sudan
2. School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, 11800 USM Pulau Pinang, Malaysia
3. Hospital Pulau Pinang, Jalan Residensi, 10990 Pulau Pinang, Malaysia
4. Department of Community Medicine, School of Medical Sciences, Universiti Sains Malaysia Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia