The first time I encountered this notable disease was in 2005. My professor at the time had a frozen frame with European Foulbrood. He held up the frame and asked what we saw wrong with it. The first thing I noticed was the shotgun brood pattern. I looked closely and observed contorted/twisted larvae. The symptom is caused by the bacteria Melissococcus plutonius. The larva dies before the cell is sealed because the bacteria out-compete the larvae for the food. The images below demonstrate symptoms I first noted.
The next time I saw this unique disease was the summer of 2008. A beekeeper called with concern, that one of his hives was not doing well and the larvae looked “Funny.” So I headed out to inspect the hives on a bright sunny day. I remember this yard very distinctly, there was a row of hedges and a garden with two honey bee colonies painted white at the end of the row. Upon approaching these hives I noticed a strong odor of what to me smelled like “moldy cheese.” This interested me because it did not smell like AFB. I did recall reading that sometimes EFB has a fishy odor, so I monitored the entrances of the two hives for a minute and cracked the lid on the stronger hive. When inspecting this hive I found no signs of EFB or any other diseases.
When entering the next colony, I used my hive too to remove the inner cover; I instantly found the source of the strong smell. After removing and inspecting a few frames it was clear that the hive was infected with European Foulbrood. Some of the symptoms, besides the characteristic smell, are pictured below. Note that there are several other bacteria commonly found amongst M. plutonius. The associated bacteria can be linked with different odors and symptoms. The disease can be odorless so this symptom alone cannot diagnose the disease.
Fortunately the beekeeper can clean up this disease pretty easy. I recommended the beekeeper use Terramycin to clear up the disease. A few months later I saw the beekeeper at a beekeeping association meeting I was speaking at and he said that the Terramycin worked great and bees were healthier within two weeks. It is always nice to get the beekeepers feedback; it helps me learn more about the bees, treatment and beekeepers.
