1. School of Medicine, Belgrade + Clinical Center of Serbia, Clinic of Infectious and Tropical Diseases, Belgrade
2. Faculty of Medicine, Novi Sad + Clinic of Infectious Diseases, Novi Sad
3. Faculty of Medicine, Niš + Clinic of Infectious Diseases, Niš
4. Faculty of Medical Sciences, Kragujevac + Clinic of Infectious Diseases, Kragujevac
5. School of Medicine, Belgrade + Zvezdara Clinical Hospital Center, Department of Gastroenterology and Hepatology, Belgrade
6. School of Medicine, Belgrade + Clinical Center of Serbia, Clinic of Gastroenterohepatology, Belgrade