Received: 19 September 2019
Accepted: 5 April 2020
First Online: 19 April 2020
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee of, Al-Neelain University, Khartoum, Sudan. Participation was on a voluntary basis, and the residents were randomly selected and a written informed consent was obtained from all participants after explanation of the study objectives and prior to the study procedures and blood collection. The risk factors information was obtained from the residents through the structured questionnaire form, permitting the use of their blood samples for diagnostic and research purposes.
: Not applicable.
: The authors declare that they have no competing interests. The result of this study does not reflect the opinion of the funding sources. All authors have read and approved the final version of this manuscript.