1. 1Laboratory of Biomedical Research, Ahfad University for Women, P.O. Box 167, Omdurman, Sudan
2. 2Tropical Medicine Research Institute, P.O. Box 1304, Khartoum, Sudan
3. 3Post-graduate Program in Health and Environment, University of Tiradentes, Aracaju, Brazil
4. 4Department of Medicine and Nursing, University of Tiradentes, Sergipe, Brazil