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20161
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Subject: Veterinary Parasitology × Author: Bulbul, Kamal Hashan × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    STUDIES ON Indoplanorbis exustus AND ITS ASSOCIATED SCHISTOSOMES
    (Assam Agricultural University, Khanapara, Guwahati, 2016-07) Bulbul, Kamal Hashan; Das, Manoranjan
    A study on ecology, biology and bionomics of Indoplanorbis exustus along with its associated schistosomes was undertaken for a period of two years i.e. from March 2014 to February 2016 in Barpeta, Nalbari and Kamrup district of Assam. A total of 12 aquatic macrophyte species were recorded from the study area. The highest frequency percent (f %) relative frequency percent (RF %) of different macrophytes was found to be 86.67% and 19.70% respectively. Population density of I. exustus in terms of f% and RF% and man hour collection per meter square area (MHC/m2) showed an increasing trend from July to September and then gradually declining towards November. While the snails were reared in biologically balanced aquarium at constant temperature of 15, 20, 25, 30 and 35C and room temperature (20.02-31.75C), all the snails died before attainment of sexual maturity at 15oC. The growth rate in terms of shell diameter and body weight attained maximum size 10.63+0.162 mm and 435.83+23.367 mg, respectively at room temperature at 6th week of age. Egg to egg cycle ranged from 50 days at 30C and 125 days at 20C. Room temperature was found to be more conducive for fecundity wherein as many as 22833 numbers of eggs were hatched out from 1033numbers of egg capsules. The temperature, pH, DO, free CO2 and total alkalinity of ambient water had direct bearing on population density of snails. The ANOVA of physicochemical properties of water was highly significant (p<0.01) between months and areas of water bodies. Out of 161500 numbers of snails collected in two years showed incidence rate of cercariae of Schistosoma spindale (0.72%), S. indicum (0.50%) and S. nasale (0.17%). The cercariae were identified on the basis of morphological and molecular method. The RS data indicated that the distribution of cercariae of S. indicum group was more in the northern bank of Brahmaputra compared to the Southern bank. By means of molecular dissection, brevifurcate cercaria was identified as Trichobilharzia sp. and the longifurcate as Alaria alata with 87-88% clonal relationship with Denmark, Lithuania and Germany isolates. A total of 420 cattle, 179 buffaloes and 171 goats slaughtered at local abattoirs revealed visceral schistosomosis in 37.38, 35.20 and 12.28%, respectively. In regards to coprological examination it was 14.52, 12.85 and 4.68% in order of same sequence as above. The incidence rate in terms of adult parasites present and faecal examination was the highest in monsoon season and the lowest in pre-monsoon season. Concentration of eggs was more in liver (45.45%) followed by ileocaecal junction (37.50%), caecum (25.97%) and small-intestine (18.18%). Based on worm count methods, mild types of intensity was found to be highest followed by moderate and heavy intensity in slaughtered animals. The incidence of nasal schistosomosis was highest in July (18.92%) and lowest in December (2.70%) when nasal swab was examined for the presence of eggs in 363 cattle irrespective of sex and age. Like visceral schistosomosis, nasal schistosomosis also had a higher infection rate in monsoon season and in animals above 8 years of age. The second internal transcribed spacer (ITS2) sequence of S. spindale, S. indicum and S. nasale were found to be amplified showing different repeatitive band patterns. While the mitochondrial cytochrome c oxidase subunit 1 (CO1) genes and the ribosomal gene repeat, part of the 28S RNA gene (28S) were amplified on 372 bp and 1225 bp when subjected to PCR. Phylogenetic analysis of Schistosoma indicum group based on nucleotide sequences of COI and 28S genes revealed Assam isolates of S. indicum showed a clonal relationship with Bangladesh isolates and S. spindale and S. nasale with Nepal isolates. RAPD-fingerprinting using different random primers showed specific polymorphic markers for susceptible and non-susceptible I. exustus to Schistosoma infection due to genetic variability.