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Assam Agricultural University, Jorhat
Assam Agricultural University is the first institution of its kind in the whole of North-Eastern Region of India. The main goal of this institution is to produce globally competitive human resources in farm sectorand to carry out research in both conventional and frontier areas for production optimization as well as to disseminate the generated technologies as public good for benefitting the food growers/produces and traders involved in the sector while emphasizing on sustainability, equity and overall food security at household level.
Genesis of AAU -
The embryo of the agricultural research in the state of Assam was formed as early as 1897 with the establishment of the Upper Shillong Experimental Farm (now in Meghalaya) just after about a decade of creation of the agricultural department in 1882. However, the seeds of agricultural research in today’s Assam were sown in the dawn of the twentieth century with the establishment of two Rice Experimental Stations, one at Karimganj in Barak valley in 1913 and the other at Titabor in Brahmaputra valley in 1923. Subsequent to these research stations, a number of research stations were established to conduct research on important crops, more specifically, jute, pulses, oilseeds etc. The Assam Agricultural University was established on April 1, 1969 under The Assam Agricultural University Act, 1968’ with the mandate of imparting farm education, conduct research in agriculture and allied sciences and to effectively disseminate technologies so generated. Before establishment of the University, there were altogether 17 research schemes/projects in the state under the Department of Agriculture. By July 1973, all the research projects and 10 experimental farms were transferred by the Government of Assam to the AAU which already inherited the College of Agriculture and its farm at Barbheta, Jorhat and College of Veterinary Sciences at Khanapara, Guwahati.
Subsequently, College of Community Science at Jorhat (1969), College of Fisheries at Raha (1988), Biswanath College of Agriculture at Biswanath Chariali (1988) and Lakhimpur College of Veterinary Science at Joyhing, North Lakhimpur (1988) were established. Presently, the University has three more colleges under its jurisdiction, viz., Sarat Chandra Singha College of Agriculture, Chapar, College of Horticulture, Nalbari & College of Sericulture, Titabar. Similarly, few more regional research stations at Shillongani, Diphu, Gossaigaon, Lakhimpur; and commodity research stations at Kahikuchi, Buralikson, Tinsukia, Kharua, Burnihat and Mandira were added to generate location and crop specific agricultural production packages.
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ThesisItem Open Access Pathomorphological and molecular detection of avian leukosis virus infection in chicken(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Tamuly, Nibedita; Dutta, BiswajitAvian Leukosis being a common neoplastic disease of the commercial poultry farm, causes significant economic losses to the farmers. The present study was undertaken to determine the status of the infection in the poultry population from 7 different locations in Kamrup district of Assam. During the period of study, twenty two (22) outbreaks of avian leucosis were recorded from seven (7) different locations of undivided Kamrup district of Assam. A total 243 numbers of post mortem was conducted from which 65 positive cases were reported on the basis of gross examination, histopathological alteration and molecular detection. The overall mortality percentage was recorded as 4.11%. Among different age groups maximum mortality was reported in adult birds above 20 weeks of age (7.36%). However few cases were also reported below 16 weeks of age. Breed/strain wise study revealed highest mortality was reported in BV-380(6.17%) followed by BV-300 (4.47%) which was further followed by Kamrupa (3.49%) and Daothigir (3.47%). Season wise occurrence of the infection was more during winter (4.86%) followed by pre-monsoon (4.11%) and post monsoon (3.68%). Clinically, affected birds did not exhibit any typical clinical signs, however some of the affected birds showed signs like anaemia with pale comb, emaciation with decrease growth rate and productivity and osteopetrosis. The gross pathological study gives a presumptive diagnosis of the diseases where prominent lesions were found in liver, spleen, kidney and heart. In all the cases hepatomegaly was most commonly seen. The affected liver also showed nodular, eucosis or diffuse form of lesions. Spleen, kidney and heart also showed enlargement, necrosis and the presence of nodular growth. Even though the bursal involvement could not be detected due to its rudimentary form in adult birds but in two cases the lesions in bursa was prominent. Microscopic alterations were severe in liver, spleen, kidney, heart and lung characterized diffuse infiltration of immature lymphoid cells, causing distortion of normal parenchyma. Molecular detection by targeting gp85 env gene produced amplification bands at 229 bp. The phylogenetic analysis of the resultant sequences showed 99-100% homology with the endogenous forms of isolates from China, USA and South Korea. Virus can be isolated on 6th day old embryo where replication of the virus was showed by severe hemorrhages and mortality 48-96 hours of post infection. In field condition presence of other neoplastic diseases like Marek’s disease produces similar lesions which complicates proper diagnosis of avian leucosis. In such situations differential diagnosis can be made on the basis of cell cytology, histopathology and Polymerase chain reaction. In histopathology Marek’s diseases affected tissue showed infiltration of pleomorphic cells and on molecular detection positive samples produced bands at 225bp. Myeloid form and erythroid forms were not found during the study. And the present study reveals that infective form of subgroup E of avian leucosis is circulating in the residential poultry population which might undergo mutation along with exogenous forms and create a more severe form of the disease.ThesisItem Open Access Pathomorphological and molecular studies of respiratory mannheimiosis in goats(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Mazumder, Amdedul Islam; Begum, Shameem AraThe present investigation was conducted to study the pathomorphological and molecular studies of respiratory Mannheimiosis in goats for a period of one year from March 2021 to February 2022. The materials for the present study were collected from various sources such as slaughter houses in and around Guwahati and from postmortem examinations carried out in the Department of Veterinary Pathology, College of Veterinary Science, A.A.U., Khanapara, Guwahati-22. Based on gross observation 30 lungs showing lesions of pneumonia were collected during post mortem examination. Twenty one lung samples showing pneumonic lesions were also collected from slaughter houses. For detailed bacteriological and pathological studies all of the 51 pneumonic lungs were chosen. A total of 43 isolates of bacteria were obtained in the present study out of which seven isolates were morphologically and biochemically positive for Mannheimia haemolytica (16.28%). Apart from this, other bacteria isolated were Pasteurella multocida (23.26%), E. coli (20.93%), Klebsiella spp. (18.60%), Staphylococcus spp. (13.95%) and Streptococcus spp. (6.98%). All the 7 isolates of Mannheimia haemolytica were screened for Lkt and 16s rRNA gene respectively. The Lkt gene with amplicon size 206 bp and the 16s rRNA gene with amplicon size 1500 bp was detected in all the 7 isolates of Mannheimia haemolytica. The Phylogenetic analysis of 16s rRNA gene of Mannheimia haemolytica isolated from goats in the present study showed percent identity above 97 percent with other strains of Mannheimia haemolytica present in the NCBI Gene Bank throughout the world. Different types of pneumonia associated with respiratory Mannheimiosis recorded during the present study were bronchophneumonia (37.25%), interstitial pneumonia (27.45%), haemorrhagic pneumonia (19.61%), suppurative pneumonia (11.76%), and fibrinous pneumonia (3.92%). Patchy areas of consolidation in the cranioventral portion of lungs were the most commonly observed gross lesion in bronchopneumonia. Microscopically, bronchopneumonia was characterized by neutrophils and mono-nuclear cell infiltration with presence of fibrin in the bronchi, bronchiole, alveolar lumen and pleura. Interstitial pneumonia cases were characterized by enlarged and rubbery lungs which do not collapse when the thorax is opened. The interlobular septa were distended with exudate. Microscopically, alveolar wall was thickened due to infiltration of polymorphonuclear cells and lined by cuboidal epithelial cells. Alveolar lumen was also filled with polymorphonuclear cells, macrophages and desquamated epithelial cells. Haemorrhagic pneumonia cases revealed multifocal, patchy to diffuse areas of haemorrhage throughout the lung surface. Microscopically, there was hemorrhage within the alveoli and inter alveolar septa with leukocytic infiltration in the bronchus. The wall of the bronchus also showed the inflammatory changes. Areas of emphysema were also observed. Gross pathological alterations observed in suppurative pneumonia were multiple focal abscess formation on lung surface. Presence of creamy suppuration could also be noticed in tracheal lumen. Microscopically, heavy infiltration of neutrophils could be seen in bronchial and alveolar lumen. In some cases necrotic mass admixed with bacterial colonies surrounded by thick connective tissue capsule were also recorded with infiltration of polymorphonuclear cells, mononuclear cells, plasma cells and macrophages. In fibrinous pneumonia, lungs were covered with stringy net like material. Excess serous fluid was present in the pleural and peritoneal cavities. In few cases the lungs was tightly adhered to the thoracic wall due to deposition of fibrin. The interlobular septa were prominent due to accumulation of fibrin. Microscopically, fibrinous pneumonia was characterized by the presence of intra alveolar fibrin in the form of “fibrin balls” within the alveolar spaces. The traditional ‘oat cells’ and necrotic macrophages were present inside the damaged alveoli.ThesisItem Open Access Pathology and molecular diagnosis of helicobacter infection in pig(College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Dutta, Kongkon Jyoti; Tamuli, Sarojini MahantaHelicobacter is a zoonotic bacterium that has been associated with gastritis and ulcearative lesion in the stomach of pig. Prevalence of Helicobacter infection in pig was determined from four districts of Assam during the period from July, 2021 to June, 2022. The prevalence of Helicobacter infection was found to be 39.9% and 45.67% by RUT and PCR test, respectively. The age wise prevalence of Helicobacter infection revealed highest in adult pigs 42.37% (RUT) and 48% (PCR) in comparison with piglet 23.07% (RUT) and 16.66% (PCR). Among different farms the highest prevalence was recorded in unorganized farms 45.53% (RUT) and 52.17% (PCR) in compared to organized farms 32.96% (RUT) and 37.10% (PCR). The presence of HLOs in different regions of the stomach by RUT was recorded as Parsoesophagea (1.48%), Cardia (2.95%), Fundus (15.27%), and Pylorus (20.27%). The maximum positivity was recorded in pylorus and fundus region with 20.27% and 15.27% respectively. The presence of HLOs in different grades of gastric macroscopic lesions was determined. The positivity of HLOs in different grades of gastric macroscopic lesions recorded as: 1+ (Early or mild) (28.12%), 2+ (Severe) (37.03%), and 3+ (more severe+ ulcers) (56.89%). The maximum positive RUT was detected in Grade 3+ (58.89%). HLOs were detected by brush cytology from the mucosal surface satined with Giemsa and Gram’s stain in 22.66% and 16.74% of the samples respectively. The gross lesions of gastritis were recorded in 203 (58%) stomachs out of 350 pig carcasses examined. The present investigation recorded early or mild gastric lesions (1+) in 31.53%, severe lesion (2+) in 39.90% and more severe lesions and ulceration (3+) in 28.57% of the stomach examined grossly. The recorded lesions were various grades of lesions as thickening of the gastric wall, corrugation of the gastric folds, congestion and haemorrhages, necrosis and sloughing of the gastric mucosa, erosions and ulceration in the parsoesophagea as well as glandular regions of the stomach. The frequency of various histopathological lesions in affected stomach were Hyperkeratosis (17.28%), Parakeratosis (14.81%), Epithelial hyperplasia (44.44%), Glandular degeneration (60.49%), Vacuolation of glandular epithelium (56.79%), Lymhoid follicle (62.96%), Inflamatory cell infiltration (Neutrophil (32.09%), Lymphocyte (45.67%), Eosinophil (23.45%), Macrophage (28.39), Plasma cell (25.92%), Sloughing & erosion (53.08%), Ulcer, Congestion and Haemorrhages (39.50%), Glandular abscess (9.87%), Fibrosis (4.93%), Metaplasia and Dysplasia (3.70%), and Detection of Helicobacter (9.87%). Ultrastructurally, Helicobacters with bacillary morphology, inflammatory cells on the gastric mucosa and biofilm formation by coccoid form of Helicobacters were detected. PCR analysis of the gastric samples showed the presence of Helicobacter spp in 37 (45.67%) and Helicobacter suis in 17 (20.98%) samples. PCR detection rate was found to be higher from the pylorus and fundic region and severe gastric lesions of the stomach. To study the zoonotic potential of Helicobacters, a total of 30 saliva samples from pig farmers were subjected for PCR out of which Helicobacter spp. was detected in 8 numbers of samples. Further, Helicobacter suis (2) and Helicobacter pylori (3). Phylogenetic analysis revealed that Helicobacter suis detected from pig handlers and pig stomach samples shares above 99% identity suggesting zoonotic transmissions of Helicobacters from pig to human.ThesisItem Open Access PATHOMORPHOLOGICAL AND MOLECULAR DIAGNOSIS OF INFECTIOUS BURSAL DISEASE(College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, 2020-12) ISLAM, MUZAHARUL; GOSWAMI, S.The present investigation was carried out to know the pathomorphology of Infectious Bursal Disease in different organized and un-organized poultry farms in and around the Guwahati city, Kamrup district, Assam. Altogether 1650 birds were necropsied, out of which 1279 birds from 29 different outbreaks were diagnosed as suspected of IBD based on gross lesions observed. Clinical signs commonly recorded were vent pecking, dullness, depression, anorexia, ruffled feathers and yellowish white diarrhea. In gross pathological study, bursa of Fabricius were found to be invariably affected with lesions like swelling, edema and hemorrhage. Few bursa of Fabricius showed atrophy. Moderate to severe haemorrhages in the breast and thigh muscle were consistently observed. The kidneys were enlarged and mottle with whitish pale colour appearance. Hemorrhagic lesions were also noticed in extra bursal lymphoid organs like spleen, thymus and caecal tonsils. Histopathologically, there were mild to severe depletion of lymphocytes in the bursa of Fabricius, spleen, thymus and caecal tonsils. Heterophilic infiltrations were also consistently observed in these organs. Complete depletion of lymphocytes with formation of cystic cavity were noticed in some bursal follicle. Marked thickening of the inter-follicular space with proliferated fibrous connective tissue were another characteristic bursal lesion observed. Muscle sections revealed haemorrhages and necrosis. Kidney showed degenerative changes and necrosis in proximal and distal convoluted tubules. There were glomerular shrinkage in few cases. Degenerative changes of the hepatocytes were the commonly observed histopathological changes in liver. In scanning electron microscopic study of bursa of Fabricius, moderate to severe erosion and ulceration of mucosal plica and exposure of reticular fibers were noticed after exuviations of epithelial and other cells were noticed. Button like depressed structures were seen in follicles and some follicles appeared as empty craters due to complete lymphocytic depletion. Spleen and thymus also showed moderate to severe lymphocyte depletion characterized by presence of homogenous mass. In transmission electron microscopic, spherical virus particle without a clear membrane were observed in the cellular debris of the cytoplasm of the follicular cells. Mitochondrial changes like crystolysis were also recorded. ABSTRACT The disease was confirmed by detection of viral antigen and viral nucleic acid in 165 representative samples by Indirect IPT and 612 representative samples by RT-PCR.ThesisItem Open Access PATHOLOGY AND MOLECULAR DIAGNOSIS OF NECROTIC ENTERITIS IN CHICKEN(College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, 2019-07) BEHERA, DEBASISH; Pathak, Debesh ChandraThe present research work was carried out with an aim to study the pathology necrotic enteritis with isolation and molecular detection of C. perfringens and experimental production of the NE in chicken to compare between the C. perfringens type A and C in terms of hematological, biochemical and pathomorphological alterations. Total 320 numbers of samples based on different clinical signs/pathological conditions were collected from 15 districts of Assam. Isolation and identification of C. perfringens was done by cultural and morphological characteristics and confirmation was done by detection of cpa gene of C. perfringens by PCR. In this study 20 (15.03%) intestinal content and 9 (4.81%) cloaca swabs were found to be positive for cpa gene of C. perfringens. Isolation of bacteria from the samples collected during monsoon was found to be highest in comparison to other seasons. Study showed around 80% of the total isolates of C. perfringens was from the birds of 4-6 weeks of age. The C. perfringens isolated from the enteritis samples were found to be highest. Total 29 samples were found to be positive for cpa gene (324 bp) encoding for alpha gene and cpb gene (180 bp) encoding for beta gene was detected in 11 isolates. The additional virulence toxin genes of C. perfringens like TpeL and NetB were also detected. The gross lesions of NE in field condition revealed haemorrhagic, eroded, detached dead mucosal tissues in intestine. Formations of diphtheritic membrane, distention of intestine were also observed in intestine. Liver, kidneys and lungs showed congestion, haemorrhage and focal areas of necrosis. Spleen and Bursa of Fabricious in some birds was found to be moderately enlarged. The gross lesion of brain was found to be limited to mild congestion of meningeal blood vessels. Histopathology of NE in chickens revealed congestion of blood vessels in the lamina propria and submucosa with vacuolation of epithelial cells of intestinal villi along with necrosis making the villi broader and shorter. Different developmental stages of coccidia were also seen in the mucosal epithelial cells. In other organs such as liver, kidneys, heart, lungs, spleen, bursa of Fabricius and brain showed variable nature of histopathological lesions like congestion, haemorrhage and focal areas of coagulative necrosis. Experimental production of NE was done in chicken by infecting C. perfringens isolate Type A and type C with and without coccidia in separate groups. The clinical signs shown by the experimentally infected birds were diarrhoea, dehydration, depression, reluctance to move, loss of appetite, ruffled feathers, drooping of wings and head and huddling. The clinical pathology of experimental birds showed, significant decrease in TEC level, hemoglobin (g/dl) level as well as in PCV (%) and significant increase in TLC in the birds of infected group in comparison to the control. Serum ALT and AST both showed a significant increase (P<0.01) and total protein showed a significantly decreased (P<0.05) level. The gross lesion revealed congestion and haemorrhage and focal areas necrosis of mucosa of intestine. Enlargement, congestion, haemorrhage with focal areas of necrosis of the liver were common gross findings in all the experimentally infected groups. This might be due to damage to RBC in entero-hepatic circulation by α toxin of Clostridium perfringens. Kidneys, heart, lungs, spleen and Bursa of Fabricius revealed moderate degree of congestion and haemorrhage. Variable degrees of vascular changes in terms of gross lesions were observed in all most all the infected groups. The histopathological lesions revealed developmental stages of coccidia (schizonts & merozoites) and infiltration of large no of mononuclear cells and few polymorhonuclear cells in intestine. The intestinal villi have undergone necrosis and necrosed cells were sloughed off from the mucosa. Liver revealed marked fatty change in hepatocytes, congestion in the sinusoids. Kidneys showed focal areas of inter tubular congestion. Heart and lungs revealed focal areas of mononuclear cell infiltration as well as congestion and haemorrhage. Spleen and Bursa of Fabricius showed depletion of follicles and brain showed neuronal degeneration and necrosis with neuronophagia. Based upon the clinical signs, gross and histopathology, the present study revealed the groups infected by both coccidia and clostridial isolate showed distinctly more pronounced qualitatively and quantitatively in terms of clinical signs and pathological lesions. It has been also observed in this study that C. perfringens type A was found to be more virulent in terms of pathogenesis and pathomorphology in comparison to C. perfringens type C. TEM evaluation of experimentally infected birds showed disruption of intercellular junctional complexes, formation of gaps between enterocytes and delimitation of boundaries of individual enterocytes. Disintegration of nuclear material, dilatation of endoplasmic reticulum, disruption of cristae of mitochondria, increase intracytoplasmic vacuolizations and membrane bound vesicles were also prominent ultrastructural alterations in this study. Data were subjected to statistical analysis and analyzed by SAS System ('Local', X64_7PRO) using one way analysis of variance (ANOVA). Means were presented as mean ± standard error (SE) and were compared by the Duncan test at the 0.05 level of probability.ThesisItem Open Access PATHOLOGY OF HEPATO-RENAL DYSFUNCTION IN DOGS (Canis lupus familiaris)(College of Veterinary Science, Assam Agricultural University Khanapara, Guwahati-781022, 2016-07) Umesh, Tari Chubita; Tamuli, Sarojini MahantaAn investigation was carried out in naturally occurring hepatic and renal dysfunctions in dogs from in and around Guwahati city; to study the prevalence, clinical symptoms, hemato-biochemical changes, urine pathology, gross and histopathology and histoenzymic activity. During the period from June, 2015 to May, 2016; a total of 9564 dogs were surveyed for incidence of hepato-renal dysfunction; 511(5.34%) were recorded as positive out of which 148 (1.55%) were positive for hepatic, 182 (1.82%) for renal and 181 (1.89%) for hepato-renal dysfunction. This revealed that hepato-renal dysfunction is prevalent in the dogs of Guwahati region. In a detailed examination of 155 dogs, 87 (56.13%) were reported positive for both hepatic and renal dysfunctions, out of which 31 (20%) were positive for hepatic, 35 (22.58%) for renal and 21 (13.54%) were positive for hepato-renal dysfunctions. Hepatic dysfunction showed highest prevalence in pre-monsoon season (21.95%); renal dysfunction showed highest prevalence in winter season (27.02%) and hepato-renal dysfunction showed highest prevalence in post-monsoon (23.08%) season. The age-wise prevalence for hepatic dysfunction was highest in dogs belonging to age group of 1-˂3 years of age (33.33%), for renal dysfunction it was the age group of 9 years and above (37.04%) and in hepato-renal dysfunction highest prevalence was seen in the age group of 6-˂9 years (23.53%). Sex wise prevalence of hepatic dysfunction was higher in males (22.47%) whereas prevalence of renal dysfunction was higher in females (25.76%). But the prevalence of hepato-renal dysfunction was found to be almost equal in both males (13.48%) and females (13.64%). Breed wise prevalence of hepatic dysfunction was highest in German Shepherd breed, for renal dysfunction it was highest in Pug breed and for hepato-renal dysfunction, highest prevalence was also seen in German Shepherd breed. Mortality due to hepatic, renal and hepato-renal dysfunction was found to be 18.06%, with 3.87% mortality for hepatic dysfunction, 3.22% mortality for renal dysfunction and 10.96% mortality for hepato-renal dysfunction. The clinical symptoms observed were elevated body temperature, anorexia, dehydration, dull and depressed appearance, rough body coat, pale mucous membrane, rapid pulse rate, shallow breathing, emaciation, anaemia, vomiting, diarrhoea, edema, melena, dark yellow to coffee colored urine. Some cases showed exclusive hepatic dysfunction signs of jaundice, ascites and abdominal pain. Some cases showed signs of renal dysfunction like stranguria, oliguria, urea breath and ulcers in the mouth. Giemsa’s stain and Modified Knott’s method were used for detecting hemoparasites like Babesia gibsoni, Babesia canis, Ehrlichia canis and Dirofilaria immitis in the blood of affected dogs. Hematological parameters like hemoglobin, packed cell volume, total erythrocyte count, mean corpuscular volume and mean corpuscular hemoglobin concentration revealed that dogs suffered from normocytic and normochromic anaemia. Biochemical markers included in liver and kidney function tests revealed that affected dogs showed mild to severe dysfunction of liver and kidneys. Postmortem study revealed several changes in liver like centrilobular necrosis, bridging necrosis, steatosis, acute hepatitis, portal cirrhosis, Glissonian cirrhosis, biliary cirrhosis, cholangitis, hemosiderosis and glucocorticoid hepatopathy; and also in kidneys like acute interstitial nephritis, acute glomerulonephritis, chronic interstitial nephritis, membranous glomerulonephritis, membrano-prolifereative glomerulonephritis, sclerotic glomerulonephritis, protein losing nephropathy, oxalate nephrosis, amyloidosis and calcification of tubules and glomeruli. Other organs like spleen, lungs, heart, stomach, intestine and brain were also observed to be affected. Three dogs revealed neoplastic changes like hepatocellular carcinoma, renal carcinoma and metastatic cancer of liver, kidneys and lungs. Special stains like Masson’s Trichome, Periodic acid Schiff’s, Von Kossa’s and Prussian blue stains were used to differentiate the specific changes in the affected tissues which did not appear very pronounced by routine staining methods. Histoenzymic study revealed mild to no activity of LDH in degenerated cells and AKP enzyme showed moderate to high activity in the degenerated cells and sinusoidal spaces of the liver and kidneys.ThesisItem Open Access STUDIES ON THE PREVALENCE, PATHOLOGY AND MOLECULAR DIAGNOSIS OF DUCK VIRUS ENTERITIS IN ASSAM(Assam Agricultural University, Khanapara,Guwahati, 2016-06) SAHARIAH, PARAG JYOTI; Upadhyaya, T.N.Duck plague or duck viral enteritis is an acute and contagious and economically important viral disease of ducks having high morbidity and mortality rate. A total thirty nos. of duck plague outbreaks occurring in certain district of Assam were attended during the period of February, 2014 to March 2016. Out of a total 5252 ducks at risk, 2956 (56.28%) were affected clinically and 2449 (46.62%) died. The overall morbidity and mortality were 56.28% and 46.62% respectively, however the cause specific mortality for DP in the present study was found to be 82.85%. Highest mortality was recorded in duckling (55.80%) followed by grower (51.24%) and adult ducks (35.43%) respectively. In the present investigation, altogether 445 serum samples were collected from the ducks from affected as well as some other ducks from the surrounding areas of the outbreak from different parts of Assam. All the serum samples were subjected to indirect ELISA test for detection of the duck plague viral antibody. Out of the total 445 serum samples tested for detection of DP viral antibody, 171 (38.42%) serum samples showed positive in ELISA. A total of 131 numbers of duck carcasses were subjected to necropsy examination. Externally, the carcasses were markedly emaciated, the vent was soiled with greenish-white faecal materials and occulo-nasal discharges were also observed. Grossly, the vascular changes were invariably present in all the visceral organs including the brain. The longitudinal folds of the esophagus showed presence of thick yellowish-white patchy diphtheritic membrane. In a few cases, the intestinal annular bands appeared as intensely reddened rings due to haemorrhages and were visible from external and internal surfaces. The liver was moderately enlarged with presence of scattered petechiae and focal greyish-white necrotic areas. The coronary vessels of the heart were engorged. There was presence of petechiael to echymotic haemorrhages in the epicardium particularly in and around the coronary groove, which give the heart a characteristics paint brush appearance. Microscopic lesions were characterized by haemorrhages, congestion, degeneration and necrotic changes of the parenchymatous organs. Liver showed varying degrees of degeneration with multiple areas of focal coagulative necrosis. Intra-nuclear, eosinophilic inclusion bodies with a distinct halo were observed inside the degenerated hepatocytes. Congestion of the blood vessels in the myocardium, haemorrhages between the muscle fibres and epicardium of heart were evident. There were rupture of the blood vascular wall and escape of blood into the surrounding musculature. The intestinal annular band showed congestion, haemorrhages and depletion of the lymphocytic cell populations. Lymphocytic depletion was also observed in the spleenic and bursal follicles. For in-situ demonstration of the DP virus Fluorescence Antibody Test was used. On fluorescent microscopy (FAT) DP virus was demonstrated in the liver, spleen, bursa of Fabricius, brain, thymus and intestinal annular band. A total of 380 numbers of samples were collected from clinically affected (107) and dead ducks (273) for molecular diagnosis of the disease. Out of total 380 samples, 231 (84.61%) post mortem samples and 68 (63.55%) clinical samples showed positive for duck plague virus specific nucleic acid. Highest numbers of tissue samples that showed positive for PCR were liver (91.80%) and spleen (91.53%). In clinical samples 79.10 per cent was positive in whole blood, 40.91 percent was positive in cloacal swabs and 33.34 percent in tracheal swab. In biochemical study, the ALT and AST activities in serum and tissues were significantly higher in DP affected ducks in comparison to the healthy ducks. The virus could be successfully isolated in 9-11 day old duck embryos from the field samples. The infected CAM and the embryos showed extensive haemorrhages throughout the body. Embryopathy was observed within 4-8 days post infection.ThesisItem Open Access EXPERIMENTAL STUDIES ON ACUTE AND CHRONIC CHLORPYRIPHOS TOXICITY IN INDIGENOUS CHICKEN(Assam Agricultural University, Khanapara, Guwahati, 2013-06) BEGUM, SHAMEEM ARA; Upadhyaya, T. N.The present study was conducted in thirty two numbers of 3 months- old indigenous chickens. The birds were divided into three different groups viz. Group A, Group B and Group C. Group C was given no treatment and served as control for both the treatment groups. Group A Birds served as acute toxicity group and were administered a single LD50 dose of chlorpyriphos i.e. 32 mg/kg body weight. Blood was collected from wing vein or jugular vein at zero hours and post treatment at every 2 hrs interval up to 6 hrs, then at 12 hours and subsequently at 12 hrs intervals till death. Group B birds served as chronic toxicity group and were administered with 1/90th of LD50, i.e. 0.36 mg/kg body weight of chlorpyriphos WW in acute toxicity group were excitation, bloody diarrhoea and excessive salivation with drooping of wings. The birds sat on their hocks with curled toes, were unable to stand, showed tremor, convulsions and recumbency before death. In chronic toxicity group, birds showed slightly staggering gait, leg weakness, tremor and diarrhoea. Some of the birds developed curled toes with pale mucous membrane and prominent keel bones. There was reduction in body weight gain of the insecticide treated chronic toxicity group of birds. The haematological parameters (Hb, TLC, TEC) were significantly increased due to chlorpyriphos exposure in both the insecticide treated groups compared to control groups. In DLC, heterophil per cent was found to be increased and lymphocyte per cent was found to be decreased in both acute and chronic toxicity group compared to control group. Dose dependent significant increase in serum enzyme activities (alkaline phosphatase, aspertate aminotransferase, alanine aminotransferase) due to administration of chlorpyriphos were observed in both the treated groups. During the experimentation, inhibition of cholinesterase activities indicating neurotoxicity due to administration of chlorpyriphos in both the treated groups was observed. Gross lesions of chlorpyriphos treated chickens showed congestion, patchy areas of pale discolouration in the liver, with distension of the gall bladder. The striking changes in other organs, viz. kidneys, lungs and brain, were mainly congestion and haemorrhages of variable intensity with dose and time of exposure to chlorpyriphos. Histopathological alterations in the liver appeared to be dose and time dependent as evident from the severity of changes in low and high dosed chickens. The changes observed in acute toxicity were congestion, haemorrhages, focal mononuclear cell aggregation, hepatocellular necrosis, dilatation of sinusoids, mild fatty changes and disruption of hepatic cords. In addition, mild to moderate proliferation of the biliary epithelial cells around the portal vein with formation of new bile ducts were observed. Kidneys showed congestion and focal to diffuse haemorrhages in the parenchyma; cellular swelling and mild vacuolar degeneration in the tubules and focal areas of haemorrhage and coagulative necrosis along with dilatation of the Bowman’s space in the glomerulus. Lungs revealed congestion and diffuse haemorrhages with accumulation of edematous fluid and fibrous tissue proliferation in the interalveolar septa. Brain showed neuronal degeneration, satellitosis and neuronophagia in the cerebrum along with mild gliosis, demyelination and congestion. The cerebral neurons showed degeneration and formation of vacuoles in the cytoplasm. There were degenerative changes in the Purkinje cells along with demyelination in the molecular layer of the cerebellum. Intestine revealed mild haemorrhages, mononuclear cell infiltration and sloughing of mucosal epithelial cells from the basement membrane along with hyperplasia and hypertrophy of intestinal glands. The changes in the spleen were congestion and focal haemorrhages with isolated depletion of lymphocytes in the splenic follicles. Changes in the bursa of Fabricius consisted of moderate depletion of lymphocytes with congestion, interfollicular and intrafollicular haemorrhages. The harderian gland revealed mild haemorrhages, depletion of plasma cells and necrosis. Proventriculus showed mild hyperplasia of mucosal epithelium, glandular necrosis, elongation and distension of crypts and infiltration of mononuclear cells in the lamina propria. Heart showed mild haemorrhage in the myocardium. The histopathological changes in chronic toxicity were similar to that of acute toxicity but became prominent towards the end of the experimental period. Additionally, in chronic toxicity, there was mild haemorrhage in the caecal tonsils after the 3rd week of the treatment period, the intensity of which increased subsequently with mild depletion of lymphocytes in the follicles. Gross and histopathological changes in various organs of birds treated with chlorpyriphos were observed with typical organophosphorus dose dependent toxicity signs. Microscopic changes observed in different organs viz. liver, kidney, brain, lungs, spleen, caecal tonsils, bursa of Fabricius were typical to insecticide poisoning. Considerable histochemical changes were noted in the hepatocytes and biliary epithelial cells of the liver. Alkaline phosphatase showed increased activity in the proliferated biliary epithelia and moderate to strong in the sinusoids of the degenerated areas in both the treated groups. Cholinesterase activities were inhibited in the degenerated areas of the brain particularly in the grey matter in both the treated groups. Gas chromatography revealed maximum accumulation of CPF in the brain followed by muscle, liver and kidney in descending order. Ultrastructural studies showed degenerative changes in the mitochondria, endoplasmic reticulum, nucleus and cell membrane.ThesisItem Open Access MOLECULAR BASED DIAGNOSIS ALONG WITH HISTOMORPHOLOGICAL, IMMUNOHISTOCHEMICAL AND ULTRASTRUCTURAL STUDIES ON CLASSICAL SWINE FEVER VIRUS INFECTION IN PIGS(Assam Agricultural University, Khanapara, Guwahati, 2013-07) PEGU, SEEMA RANI; Rahman, T.Classical swine fever (CSF) is a fatal viral disease affecting pigs and wild boars causing severe economic loss mainly in countries with dense pig populations. The disease is prevalent in almost all pig producing states in the country, and more particularly in the north eastern states of India. Besides clinical signs, gross and histopathological examinations, a precise laboratory diagnosis is required to confirm and to take the early decision for control of the disease during large outbreaks. In the present study, a total of six outbreaks were attended from January 2011 to January 2013. One hundred sixty-nine clinical and post mortem samples were collected from CSF suspected animals of which seventy eight samples were tested to detect E2 gene region of CSFV by nested RT-PCR and 5´ NTR in Real time RT-PCR. Nested RT-PCR showed 73% positivity and Real time RT-PCR showed 83% positivity in various clinical and post mortem samples. A total of 25 samples were tested for insitu detection of CSF glycoprotein 55(Gp 55) by Indirect fluorescence antibody tests(I-FAT) in cryosections as well as in paraffin embedded tissue sections and 18(72%) samples showed positivity in cryosections, and only 8(32%) samples showed positive result in paraffin sections. However, a total of 25 samples tested by Indirect immunoperoxidase test ( I-IPT) in paraffin sections, 18(72%)samples were found positive. Haematological study revealed significant decrease in haemoglobin percent, TEC, PCV, TLC and platelet in the CSF affected animals. In DLC, significant decrease in lymphocyte percent was recorded along with relative increase in the granulocyte percent. The clinical signs of classical swine fever were inactiveness, off fed, high rise of temperature, huddling, erythematous skin lesions, conjunctivitis and posterior weakness. The gross changes recorded were turkey egg kidney, enlarged and haemorrhagic lymph nodes and button ulcers in large intestine. Histopathological alteration recorded were interstitial and glomerular nephritis, lymphoid follicular depletion in all the lymphoid organs, perivascular cuffing, degeneration and necrosis of purkinje’s cells in the brain and ulcerative lesions and necrotic enteritis in large intestine. Enzyme histochemical study revealed weak ATPase activity in the lymphoid organs indicating B cell depletion and weak nonspecific esterase activity in the lymphoid organs indicating T cell depletion in CSF affected animals. The distribution of apoptotic cells in different lymphoid tissues were detected by TUNEL staining. There was significant increase in the number of apoptotic cells, mostly lymphocytes and smaller number of macrophages in the lymphoid follicles and interfollicular areas in lymph node, spleen, palatine tonsil and ileum. Transmission electron microscopic study (TEM) revealed, thickening of glomerular basement membrane in the glomeruli, glomerular mesangial cell proliferation, shortening and swelling of foot processes along with spherical electron dense virus particle within the dilated cytoplasmic vesicles of podocytes in the kidney. In the lymph node, TEM revealed proliferation and dilatation of rough endoplasmic reticulum cisternae and loss of cristae in the swollen mitochondria in macrophages. Lymphocyte apoptosis was observed in the lymphoid follicle characterized by condensation and margination of chromatin and fragmentation of lymphocyte nuclei and cytoplasm. In the present study, nucleic acid based technique (RT-PCR) targeting E2 gene of CSFV in various clinical and post mortem samples showed a highly sensitive and satisfactory result indicated that RT PCR is a very reliable diagnostic tool with minimum time requirement for detection of CSFV during CSF outbreaks from antimortem as well as post mortem samples. However, monoclonal antibody based in-situ immunodiagnostic assays like indirect FAT and indirect IPT used in the present study could efficiently demonstrate CSFV antigen in different lymphoid and non lymphoid organs.
