Stress Related Enterocci Effect on Cultured OreochromisNiloticus and its Relations to its Economic Losses

The effect of bacteria varies from that of primary pathogen to that, the secondary invader in the presence of other disease agents, they may also serve as a stress factors and predispose fish to other diseases. Therefore, the present study was carried-out to investigate the clinical signs and P.M. lesions and isolation and identification of the causative agent. Streptococcosis is a bacterial infection among fresh water reared in aquaculture especially in the spring and summer months. The most important clinical signs and Postmortem lesions of Streptococcus infection, the Streptococcosis diseases was also known as “Pop-eye” since one of the most characteristic symptoms were the accumulation of mucopurulent exudate around the eye. The external clinical signs varied among species of infected fish. The level of Total protein, albumin and albumin / globulin ratio showed a higher level in control saline groupn followed by the control bacteria groups. And the lowest level observed in the groups treated with ammonium choloride, lime and low oxygen levl treated groups and the groups treated with S. pnumoniae showed lower levels of the protein parameters, followed by S. iniae and S. fecalis. The antibody titer level increased from 1st to 4th week. The higher level of antibody titer observed in the control bacteria group and control saline group and the lowest level observed in the ammonium choloride, then lime and low oxygen treated group. The groups treated with S. pnumoniae showed lower level of antibody titer, followed by S. iniae and S. fecalis. The higher mortality level observed in control bacteria group followed by control saline group, while the lowest mortality level observed in ammonium chloride treated group, followed by low oxygen treated group and lime treated group, respectively. Also, the mortality level observed in groups treated with S. pnumoniae of higher mortality level, followed by S. iniae and the least level observed in the groups treated with S. fecalis. The higher RLP % observed in control bacteria group treated with S. pnumoniae and the least level observed low oxygen level treated group with S. iniae. Meanwhile the other groups treated with S. pnumoniae, S. iniae and S. fecalis achived medium RLP %. Except the lim treated groups that achieved the lower RLP level. The most important histologic results due Streptococci infection were, Internally, the abdominal cavity usually contained variable amounts of purulent exudate and/or blood. A yellowish exudate often covered the peritoneum and the epicardium, and was also found in the cranial cavity. In addition, haemorrhages were also observed in muscles, spleen, liver and kidney. The liver showed vacuolar degeneration and necrosis of most hepatic cells and pancreatic acinar cellsm, liver showed wide spread vacuolar degeneration, the spleen showed focal lymphoid depletion with hemolyses of erythrocytes, als the melanomacrophages were degenerated and necrotic. Also our results indicated that, the higher weight losses due to dead fish at different treatments observed in the group infected with S. pnumoniae control bacteria group (1.17 Kg), S. faecalis low O2 group (1.04 Kg), S. pnumoniae lime (1.00 /Kg) and its economic losses were 11.70, 10.40 and 10 LE/30 cultured O. niloticus for the same groups respectively, and for each 100 O. niloticus fish the economic losses reached to 36.74, 34.37 and 33.40LE/100 fish for the previous groups, respectively.