1. Program of Tropical and Infectious Diseases, Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia; and staff and researcher at the Ethiopian Public Health Institute, Addis Ababa, Ethiopia
2. Program of Tropical and Infectious Diseases, Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
3. International Institute of Primary Health Care-Ethiopia
4. School of public health, Addis Ababa University, Addis Ababa, Ethiopia