I am new to beekeeping & I hived 2 hives this spring of Italians & Carniolan bees. About a month ago I notice inactivity with the Carniolan's. As time progressed I discovered a dead mound, but no strong odor present. A slightly fermented smell but couldn't find the queen. Within a months time the entire hive was dead. I disassembled the hive today. It's neighbors are thriving & seemingly unaffected, I added their second box a week ago & they have gotten busy. My questions are: should I be concerned with the active hives health & proximity to the dead hive, now removed. Identify what got them, my assumption is European Foulbrood, but really have no idea as this is all new to me. Lastly, what should I do with the former hive boxes? Could the hive have been treated or saved? Any help appreciated! I will attach photos of what I found when taking the hive apart. Thanks in advance!