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2016 - 201922020 - 20221
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Subject: Veterinary Epidemiology and Preventive Medicine × Start date: 2016 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Epidemiology of rabies in Assam
    (College of Veterinary Science, Assam Agricultural University, Khanapara Campus, 2022-09) Boro, Prasanta Kumar; Dutta, Jyoti B
    In an epidemiological study on rabies in 11 districts in Assam, 65 post-mortem brain samples belonging to nine species were collected by foramen magnum approach from clinically suspected domestic and wild animals and tested at the WOAH Reference Laboratory for Rabies, Hebbal, Bengaluru – 560 024, Karnataka. Simultaneously, a questionnaire survey on the community was undertaken to evaluate the epidemiological determinants on rabies transmission. Forty two (64.61 %) samples tested positive by LFA and DFA. Of the nine species, five species i.e. cattle 27 (41.53%), dog 9 (13.85%), goat 4 (6.15%), pig 1(1.53%) and pony 1(1.53%) were confirmed for rabies. Aggression in 41 (97.62%) cases was the most common signs exhibited by the affected animals before death with only one positive case (2.38%) showing paralytic signs. There was no dog bite history in 33 (78.57%) cases while 9 (21.43%) cases had. Most of the livestock were free ranging and grazed nearby protected areas where presences of wild carnivores were evident. Seasonal distribution revealed similar numbers of cases (45.24%) during rainy and flood season (July-September) and post-harvesting (December-February) winter season. Gender-wise, 20 (47.62%) positive cases of cattle and goats were either pregnant or recently calved. Prevalence of rabies was found to be highest (64.29%) in the animals more than 3 years of age, followed by the animals between 1 to 3 years (23.81%) and below one year of age (11.90%). In rural areas distribution of rabies was highest (52.31%), semi-urban (9.32%) and urban (3.08%). Distribution maps of rabies in different parts of Assam were generated based on the GPS locations of the positive cases and heat map revealed a high risk zone in the Golaghat district. The areas adjoining the tea gardens had higher rabies cases (23, 54.76%). The questionnaire survey revealed a very low level of community awareness regarding rabies and its transmission. Lack of proper information from the field staff, immediate collection of samples from field and transportation of samples to the laboratory maintaining cold chain were the major constraints found during the study.
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    ThesisItemOpen Access
    NON-CEREBRAL COENUROSIS WITH SPECIAL REFERENCE TO EPDEMIOLOGY AND MOLECULAR CHARACTERIZATION OF Coenurus gaigeri IN GOATS
    (College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, 2019-07) LAHKAR, DEEPA; Das, Bipin Chandra
    An epidemiological investigation was carried out to study the occurrence of noncerebral coenurosis in few goat rearing areas of undivided Kamrup district of Assam during the period from August, 2016 to July, 2018. In the present study, a total of 981 number of goats examined and out of which 53 animals were positive (5.40%), while the occurrence of cerebral coenurosis was recorded only 1.33 per cent. The area wise survey under undivided Kamrup district, revealed highest (7.23%) occurrence of non-cerebral coenurosis in Hajo area while goats from Khanapara area recorded maximum (2.61%) cases of cerebral coenurosis. Non-cerebral coenurosis was significantly (p<0.01) highest (10.27%) among goats of 2-3 years of age as compared to other age groups while none of the cases could be recorded in goats below 6 months of age. Similarly, the occurrence of cerebral coenurosis was also recorded highest in the age group of 2-3 years (2.66%). Sex wise, the occurrence of non-cerebral coenurosis was significantly (p<0.01) higher (8.10%) in female goats as compared to males (1.69%) in the present study. Similarly, a higher percentage of females were also affected with cerebral coenurosis than the male goats. A significantly (<0.01) higher occurrence of non-cerebral coenurosis was recorded in female goats in the age group of 2 to 3 years (14.10%) as compared to males of the same age group. Likewise the occurrence of cerebral coenurosis was also found to be the highest in adult females in the age group of 2 to 3 years than the male goats. Thigh region was found to be the most common site (26.42%) for predilection of non-cerebral coenurus cysts from where maximum number of cysts were recovered which had significantly (p<0.05) higher cyst volume, significantly (p<0.01) larger diameter with significantly (p<0.01) maximum number of protoscolices per coenurus cyst, as compared to other body locations while brain was the common site of predilection for cerebral coenurus cysts in goats. Both non-cerebral and cerebral coenurus cysts found in the present study was characterized by a thin transparent wall filled with a transluscent fluid of varying volume with presence of numerous invaginated protoscolices, were arranged in clusters and found to attach to the germinal membrane of the cyst wall. However, non-cerebral cyst was additionally enclosed by an outer fibrous connective tissue capsule. Based on the keys and guidelines of Soulsby (1982), the coenurus cysts recovered from the subcutaneous and muscle tissues of goats and from brain in the present study, were tentatively identified as Coenurus gaigeri and Coenurus cerebralis, respectively. The mean (± SE) prepatent period of adult taeniids following experimental infection of dogs with non-cerebral and cerebral coenurus cysts from goats, was found to be 60.20 ± 1.06 days (ranging between 57 to 63 days) and 56.80 ± 1.91 days (52 to 61 days), respectively. Dogs infected with non-cerebral coenurus cyst resulted in development of adult taeniids in the jejunum of small intestine from where, 32 numbers of parasites were recovered with intact scolex with evidence of hyperaemia on the mucosa. Similarly, dogs infected with cerebral cysts, also showed evidence of adult taeniids in the small intestine particularly in the jejunum and ileum. The adult taeniids of dogs derived from both noncerebral and cerebral origin, were whitish in colour, and measured 70 to 85 cm and 45 to 62 cm in length, respectively. The number of segments per worm from non-cerebral and cerebral origin was ranging from 61 to 102 numbers and 45 to 73 numbers respectively. The scolex of taeniid parasites derived from non-cerebral and cerebral origin was found to be globular in shape with four cup shaped suckers along with a prominent rostellum with double rows of rostellar hooks. The length of the large hooks in taeniids derived from cerebral origin was significantly (p<0.05) higher as compared to the large hooks of taeniids derived from non-cerebral origin. Similarly, the length of the blade of large rostellar hooks of taeniids from cerebral origin was also significantly (p<0.05) higher as compared to the blade length of taeniids from non-cerebral origin. The PCR reaction targeting amplification CO1 and NAD1 gene of Taenia multiceps yielded the expected 444 bp and 530 bp products in the present study. The pair wise alignment of both the mitochondrial CO1 gene (CC_CO1, NC_CO1) sequences of cerebral and non-cerebral cysts showed a similarity of 98-99% and 99-100%, respectively. The phylogenetic analysis based on CO1 gene sequences revealed that the present isolates (CC_CO1 and NC_CO1) were closely related to an isolate of Taenia multiceps reported from China (Accession No. KX 547641.1) and showed 99.76% and 100% similarity, respectively which they formed a single clad and thereby confirmed that both the isolates belonged to Taenia multiceps. The NAD1 gene (CC_NAD1, NC_NAD1) sequences of both type of cysts also showed similarity of 97-99% and 98-99%, respectively to the identical sequences of Taenia multiceps in the GeneBank database and confirmed the identity of the query sequence to be Taenia multiceps. The phylogenetic analysis of NAD1 sequences revealed that the present isolate CC_NAD1 was closely related with a Greece isolate (Acc. No. KR 604804.1), an Iranian isolate and two isolates from Turkey showing 99.22, 98.92, 98.60 and 98.00% similarity, with which it formed a single clad and thereby confirmed the present isolate to be of Taenia multiceps. The other isolate, NC_NAD1, although showed 99.59% similarity with an isolate of T. multiceps from Greece (KR 604804.1) but it formed a separate clad within the same cluster in the phylogenetic tree. Based on the phylogenetic analysis of CO1 and NAD1 gene sequences, it can be concluded that Taenia multiceps is the single valid species and the origin of both non-cerebral (Coenurus gaigeri) and cerebral (Coenurus cerebralis) coenurus cysts in goats in the present study. The molecular data based on CO1 and NAD1 sequences of both non-cerebral and cerebral coenurus cysts in goats was reported for the first time from Assam, India.
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    ThesisItemOpen Access
    OUTER MEMBRANE VESICLE (OMV) OF Pasteurella multocida AS POTENTIAL IMMUNOGEN FOR PIG
    (Assam Agricultural University, Khanapara, Guwahati, 2016-07) MUKHERJEE, SHYAMANANDA; Mahato, G.
    The present study was undertaken to evaluate the immunogenic potential of Outer Membrane Vesicles (OMVs) and bacterin vaccine and their comparison. Extractions were made from a highly pathogenic pig isolate of Pasteurella multocida of capsular type A. For the study, isolation of P. multocida was attempted from apparently healthy, ailing and dead pigs. Following screening of the 171 field samples collected from various places, 17 (9.94 %) were found to be positive for P. multocida. Fourteen of the 17 isolates subjected to PCR targeting species-specific gene revealed a distinct band of 460 bp, which was a confirmation of the isolates as P. multocida. Among the confirmed P. multocida isolates, nine were identified as capsular type A (1044 bp), while the remaining five were capsular type D (657 bp), based on multiplex cap-PCR results, targeting hyaD-hyaC and dcbF genes, respectively. Both OMVs and bacterin were extracted from the most pathogenic porcine isolate of P. multocida capsular type A selected on the basis of pathogenicity trial in mice. Vaccines were prepared from the OMVs extract and bacterin of P. multocida and immunized to pigs. Following immunization with vaccines prepared from both the extracted OMVs and bacterin in natural host, pig through intramuscular (i/m) route, a gradual increase in the mean serum antibody titre was observed in both the immunized groups. The vaccine prepared from the OMVs extract showed peak antibody titre on 60th day (6.40± 0.19) post-vaccination. On the other hand, the vaccine preparation with the bacterin extract showed peak titre on 28th day (6.10± 0.14) of post-immunization and no significant difference was observed between the vaccine preparations throughout the study period (upto 90 days). Based on the statistical analysis of the mean serum antibody titre at different days post-immunization with the two preparations, no significant difference was observed between the two vaccine preparations of P. multocida. The post vaccinated serum samples collected on different days were subjected for protection test in mice. The result of passive mouse protection test revealed that the 21st and 28th day post vaccination serum sample (OMV vaccine) and 28th day serum sample (bacterin vaccine) produced (100%) protection in mice.