Professor Manongi is a Public Health Specialist with a background of medicine. For many years she has worked with as a medical doctor at the Kilimanjaro Christian Medical Centre (KCMC) and Kilimanjaro Christian Medical Collage (KCMU College). She is currently an Associate Professor at KCMU College,and works as Project Manager for the Willows Impact Evaluation in Tanzania.

Professor Manongi has served as the Principal Medical Officer, at KCMC under Ministry of Health & Social Welfare (MOHSW), now known as Ministry of Health, Community Development, Gender, Elderly  and Children (MoHCDGEC) in Tanzania for several years. Since 1999 she has trained members of the health workforce, including assistant medical officers, nurses, medical doctors, and graduate residents. She has served as Primary Investigator (PI) for clinical trials and general surveys in collaboration with international institutions such as the University of London School of Hygiene and Tropical Medicine, Family Health International, the Bill and Melinda Gates Foundation, and the University of Copenhagen.