I understand this is an old post (2019), but I would like to restart this forum on EFB therapy. It seems to me that EFB is not anymore a problem of weak hives. An article in the American Bee Journal issue October 2023 describes two methods of treating EFB, and in both cases antibiotics were necessary to control the disease. The author also confirmed that EFB is highly prevalent in her area, and that she suspects an increase in virulence of the organism (new strain?). I'm currently working with a beekeeper dealing with EFB in her apiary. It has been difficult to find a standard regimen for the use of tetracycline in a beehive with EFB. I have heard the use of one treatment with tetracycline hydrochloride to repeated treatments twice a year for several years. It would be nice to advise the beekeeper with science based data of the best methods to control this disease.
Dr. Pierre Lessard