1. Croatian National Institute of Public Health, Zagreb, Croatia
2. Public Health Institute of the City of Zagreb 'Dr. A. Štampar', Zagreb, Croatia
3. Dubrovnik–Neretva County Public Health Institute, field unit Korčula/Pelješac, Korčula, Croatia
4. Dubrovnik County Hospital, Infectology ward, Dubrovnik, Croatia
5. Primary Health Care Unit Orebić, Orebić, Croatia
6. Institute for Microbiology and Immunology, Medical faculty, Ljubljana, Slovenia
7. Public Health Institute of Dubrovnik Neretva County, Epidemiology service, Dubrovnik, Croatia