The Study of the Life Cycle of Bolbophorus Damnificus and its Pathology in the Channel Catfish (Ictalurus Punctatus)

In channel catfish (Ictalurus punctatus), the digenetic trematode B. damnificus, causes morality and reduced growth. Previous research has documented the hosts for B. damnificus are: the American white pelican (Pelecanus erythrorhynchos), the snail (Planorbella trivolvis) and the channel catfish. The goals of this research were to confirm the life cycle of B. damnificus in a single life cycle study fulfilling Koch’s postulates; determine if the snail, Biomphalaria havanensis-obstructa, could serve a host for B. damnificus, and examine the pathology of B. damnificus in channel catfish. American white pelicans (AWP) were artificially infected with B. damnificus metacercariae which matured to the adult stage (4 days) and shed ova. The ova hatched (12- 53 days), releasing miracidia which infected P. trivolvis and developed into B. damnificus cercariae which were shed (23 days), used to infect catfish and matured into metacercariae in the superficial muscle (23 days). Infected catfish were fed to AWP, and the metacercariae matured to patent adults (7 days) and shed ova, thus completing the life cycle. A second study was performed to determine if the snail, Biomphalaria havanensis- obstructa found in commercial catfish ponds could serve as an intermediate host for B. damnificus. Parasite free Biomphalaria havanensis- obstructa exposed to B. damnificus ova shed cercariae that were molecularly identified as B. damnificus; confirming Biomphalaria havanensis- obstructa is a potential intermediate host for B. damnificus. A third study examined the pathology associated with B. damnificus infections in channel catfish. Cercariae, confirmed by PCR to be B. damnificus, were used to infect fingerling catfish at 200, 100, 50, 25 and 0 cercariae/ fish. The fish were euthanized 3, 4, 5 and 6 days post-infection, gross observations were noted and tissues were collected for histology. Mortalities of 20- 100% occurred in fish challenged with 200 cercariae by day 6 post-infection. At day 6 post-infection, fish challenged with 100- 200 cercariae had loss of hepatocytes vacoulation and lymphoid depletion in the spleen. Metacercariae were not only present in the subcutaneous muscle but were also in the epidermis, behind the skull, within the muscular layers urinary bladder and around the heart