Type II white-band disease

Epizootics of type II white-band disease (WBD II) can be confused with type I white- band disease (WBD I) and with bleaching. The only well documented cases of WBD II have been on Acropora cervicornis from the Bahamas, but de scriptive reports indicate that it may be widespread. WED II begins asa ble aching margin which precedes a necrotic margin. The bleaching margin usuall y progresses at a faster rate than the necrotic margin and can arrest, allo wing the necrotic margin to catch up. In this case, the disease has the app earance of WBD I. Living polyps are found in the bleached zone although rec overy has not been observed. A. bacterium, similar to Vibrio charcharia is always isolated from the surface mucopolysaccharide layers (SML) of the ble ached zone, but not from the SML of unbleached areas.