1. Department of Public Health, Medical University of Bialystok, 15-295 Bialystok, Poland
2. Department of Infectious Diseases and Allergology, Jan Kochanowski University, 25-317 Kielce, Poland
3. Department of Infectious, Tropical Diseases and Immune Deficiency, Pomeranian Medical University in Szczecin, 71-455 Szczecin, Poland
4. Faculty of Health Sciences, Klaipeda University, LT-92294 Klaipeda, Lithuania
5. Department of Environmental Medicine, Poznań University of Medical Sciences, 60-806 Poznań, Poland
6. Department of Infectious Diseases and Hepatology, Medical University of Bialystok, 15-540 Bialystok, Poland