12 research outputs found
White spot syndrome virus (WSSV) infection in tiger shrimp Penaeus monodon: A non-lethal histopathological rapid diagnostic method using paraffin and frozen sections
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No full textNot AvailableTilapia, Oreochromis mossambicus, held in sea water, was experimentally infected with Aeromonas hydrophilla (SAH 93) via intramuscular injection. The pathogen has an LD of 10 CFU/fish produced characteristic ulceration leading to open wounds. More than 80 per cent of the experimentally infected fish, injected with the doses higher than LD50, died within eight days. Dermal necrosis and liquifying muscular degeneration with infiltration of cellular serum factors to the site of injection were noticed. Focal necrosis of the hepatocytes, tubular degeneration and sloughing, glomerular necrosis, necrosis and depletion of the cells in the renal tubular interstitia, loss of sub-mucosa and sloughing of the intestinal microvilli were the major histopathological manifestations of the experimental infection. Aggregation of macrophages and melano macrophage centres (MMC) in the head kidney and spleen were also noticed. Gill lamellar basement epithelium showed mid hyperplasia and hypertrophy. Lifting and seperation of the epithelium of the secondary lamellae and arterial congestion in the primary lamellae were observed as delayed responses. The study indicated that Tilapia could be a potential carrier of A. hydrophila, and thus, has to be used with caution as a forage fish.Not Availabl
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No full textNot AvailableMud crab, Scylla serrata farming had been initiated in the abandoned vannamei ponds in Andhra Pradesh, India since 2016. Total area under mud crab culture in Andhra Pradesh was 7363.81 hectares during 2017-18. The crab farming in earthen ponds was done using the green local (GL) crabs (100-200g) from export portals (Odisha, Tamil Nadu, Puducherry, Kerala, Karnataka, Maharashtra and Goa) with the stocking density of 0.1 per sq. mt. Crab mass mortality was observed in Nagayalanka, Krishna district with clinical signs such as white spots on the carapace, lethargy, fungal growth over the skeleton, chitinolytic spot on the abdominal flap, fouling, broken claw, loss of chelate legs, and light greenish to yellowish or pinkish discoloration followed by death. Mortality was observed during 65th day of culture (DOC) and progressed up to 75% in a period of 10 days. Hence, emergency harvest was done on 75th DOC. Water and pond sediment samples were collected from diseased and healthy farms (four farms with 21 ponds). Water salinity, pH, dissolved oxygen and temperature were 16.67±0.18 ppt, 8.16±0.01, 3.75±0.06% and 26.68±0.06oC, respectively. Moribund and healthy crabs were collected with an average size of 781.25±33.56g. On spot post-mortem examination was done and the samples were collected in suitable preservatives. Post mortem examination revealed that the gills were heavily infested (left gill-74.8±11.81; right gill-72.3±11.95) with metazoan crustacean parasite, stalked barnacle, Octolasmis spp. Abdominal cavity contained about 30-40mL serosanguinous fluid. Microbial load estimation in pond sediment, water and haemolymph of infected pond were significantly higher than that of healthy ponds. Haematological investigation revealed that the healthy mud crab had higher total haemocyte count (THC) of 17.28±0.46 x 106 cells mL-1 while the diseased crabs had THC of 6.90±0.48 x 106 cells mL-1. The differential haemocyte population was characterized based on the presence of the cytoplasmic granules and cell sizes. Small non-granular (SNGH) and large non-granular (LNGH) haemocytes populations were found significantly increased while semi-granular or small-granular (SGH) and large granular (LGH) haemocytes were drastically reduced in diseased crabs compared to that of healthy crabs. Polymerase chain reaction (PCR) screening for white spot syndrome virus (WSSV) revealed that the diseased samples were positive. Histopathology showed that there was degeneration of gill tissue and were characterized by hypertrophied nuclei with marginated chromatin and eosinophilic to basophilic intranuclear inclusions. It is advisable to stock disease free crablets and follow strict better management practices to avoid disease outbreaks in future.Not Availabl
