RESUMEN
Many infectious diseases have emerged or re-emerged during the past 50 years in the Republic of Korea. Some of these are new infectious diseases delivered by new or newly recognized micro-organisms. Others are already known infectious diseases which have increased in frequency or have developed an expanded region of occurrence. Still others are infectious diseases that are caused by the same micro-organisms which are resistant to antibiotics, and therefore difficult to treat. Newly recognized Emerging Infectious Diseases (EIDs) include legionellosis, leptospirosis, tsutsugamushi diseases, Vibrio vulnificus sepsis, and brucellosis. New EIDs include acquired immunodeficiency syndrome, enterohemorrhagic E. coli infection, Creutzfeldt-Jacob disease. Of the EIDs occurred in the Republic of Korea during the past 50 years, healthcare-related infections, especially by antibiotic-resistant organisms, are the most important EIDs in terms of morbidity and mortality.