Infectious agents, infections and infectious diseases; transmission of infectious agents; specific and aspecific mechanisms of defense agasist infections; Contagious infectious diseases; upper and lower respiratory tract infections; upper and lower urinary tract infections; sexually transmitted infectious diseases; Herpesviridae infections; HIV infection; acute and chronic viral hepatitis; Sepsis; resisdent bacterial flora; gastrointestinal pathogens; composition of normal genital flora and ist dynamic modifications; gynecologic anf obstetric infecitons.