Abstract

Shells of crabs are infected with a high prevalence of diseases than any other crustacean. Bacteria, viruses, fungi and several other pathogens influence higher percentage of shell disease in crabs. Infections in crab affected growth and metabolism and it may also lead to death. This work deals with the microscopic examination of shell diseased crabs with reference to its variation in hemocytes count, histopathology and biochemical estimation. The total heterotrophic bacterial (THB) population in normal shell was found to be 5.15 x 10⁴ ± 0.09 Colony forming unit (CFU) ml^-1 and THB load was noted to be slightly increased than in normal shell and the count was 5.95 x 10⁴ ± 0.12  CFU ml^-1 in the infected shell. The current findings suggest a positive correlation between bacterial shell disease and the secondary infection affecting hemolymph (total hemocyte count), proximate composition (protein, carbohydrate and lipid) and histopathology of the animal (gills, hepatopancreas and heart). The total hemocyte count and differential count were experimented which showed lower number of total hemocytes in infected crabs while no highly accountable difference was found in differential count. Hematology studies reported total hemocyte as 9.93 x10⁶ ± 0.07 cells ml^-1 in normal and 6.525 x 10⁶ ± 0.12 cells ml^-1in shell diseased hemolymph. The level of protein, carbohydrate and lipid contents suffered a mild alteration in crabs with bacterial shell disease. Histopathology of gills hadshown variations such as dilated lamellae and hemocyte accumulation (nodules), hepatopancreas showed mild difference with increased necrosis, appearance of hemocytic nodules in the hemal spaces and heart with very mere infection while no reportable changes were accomplished in muscle tissue.

Key words: Shell disease, bacteria, hematology, histopathology, biochemical composition.