Velikova T. V.
Department of Clinical Immunology, University Hospital Lozenetz, Sofia University St. Kliment Ohridski, Sofia, Bulgaria
tsvelikova@medfac.mu-sofia.bg ,
Kotsev S. V.
Department of Infectious Diseases, Pazardzhik Multiprofile Hospital for Active Treatment, Pazardzhik, Bulgaria
,
Georgiev D. S.
Faculty of Dental Medicine, Medical University of Plovdiv, Plovdiv, Bulgaria
,
Batselova H. M.
Department of Epidemiology and Disaster Medicine, University Hospital "St. George", Plovdiv, Bulgaria