1. Slovak Medical University, Limbová 12, 83303 Bratislava, Slovakia, Pediatric Otorhinolaryngology Department of Medical Faculty of Comenius University, Limbová 1, 83340 Bratislava, Slovakia, Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, Military Aviation Hospital, Murgašova 1, 04086 Košice, Slovakia, and Hospital with Policlinics Š. Kukura, Špitálska 2, 07101 Michalovce, Slovakia