Sacbrood virus (SBV) is a viral disease of honey bees which is caused by Morator aetotulas). Sacbrood is rarely considered a serious threat, however recent estimates suggest that one larva killed by the sacbrood virus contains enough virus to kill over one million larvae. It occurs when colonies have been under stress. Bees generally clear up the disease and remove affected brood themselves.
In Asia, there are two manifestations of the disease---occurring in the honey bee (Apis mellifera) and the Asian hive bee (A. cerana). Research indicates that nurse bees act as vectors of the disease, and the larvae are infected via brood-food gland secretions of worker bees.
TransmissionIt is unknown how the virus is actually transmitted to the larvae in nature, why severe outbreaks occur only during the build-up season, or how the virus persists from year to year.