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Kerala Veterinary and Animal Sciences University, Wayanad

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20191
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Subject: Veterinary Parasitology × Author: ANBARASU K. × End date: 2019 × Start date: 2010 ×
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    ThesisItemOpen Access
    MORPHOLOGICAL AND MOLECULAR STUDIES ON THE INTRAMOLLUSCAN STAGES OF AMPHISTOMES AND SCHISTOSOMES
    (College of Veterinary and animal Science,Mannuthy, 2019) ANBARASU K.; Asha Rajagopal
    The study was undertaken in central Kerala region during the period from June 2018 to May 2019 with the objectives of determining the occurrence of snails in different habitats and seasons and detecting amphistome and schistosome infection in the predominant snail species by morphological and molecular techniques. A total of 1037 snails were collected from three habitats viz., uncultivated paddy fields, permanent water bodies and catchment areas of dams and screened for presence of trematode infection during monsoon, post-monsoon and pre-monsoon seasons. Five species of snails were identified morphologically viz., Indoplanorbis exustus, Lymnaea luteola, Melanoides tuberculatus, Pila globosa and Bellamya spp. Indoplanorbis exustus was found to be the most predominant snail species with a prevalence rate of 45.41 per cent. The prevalence rates of L. luteola, M. tuberculatus, P. globosa and Bellamyia spp. were 22.85, 15.62, 10.70 and 5.40 per cent, respectively. Highest prevalence of snails was recorded during monsoon (37 %), followed by post-monsoon (35.5 %) and pre-monsoon (27.5 %). Statistically significant association was found between the prevalence of different species of snails and seasons with I. exustus occurring more in monsoon and L. luteola more during pre-monsoon. Habitat-wise analysis of prevalence of snails revealed I. exustus and L. luteola to be predominant in permanent water bodies and uncultivated paddy fields where as M. tuberculatus showed significantly high prevalence in catchment areas of dams. Overall prevalence of trematode infection in snails was found to be 13.4 per cent. Five types of trematode cercariae were identified viz., amphistome, mamamalian schistosome, strigeid, avian schistosome and echinostome cercariae. Highest prevalence was recorded for echinostome (36 %) followed by avian schistosome (26.6 %), strigeid and amphistome (15.8 % each) while mammalian schistosome was the least prevalent (5.8%). Amphistome, avian schistosome and strigea showed higher prevalence in monsoon while echinostome infection was more prevalent in pre-monsoon and mammalian schistosome in post-monsoon. Trematode infection in snails was significantly higher in uncultivated paddy (42.4 %) followed by permanent water bodies (36 %) and catchment areas of dams (21.6 %). Highest prevalence of amphistome infection in snails was observed in permanent water bodies. Uncultivated paddy fields and catchment areas of dams showed higher prevalence of infection with trematodes of birds compared with that of animals. Molecular identification of I. exustus was done by PCR targeting 229 bp region of 16S rRNA gene. Molecular detection of amphistome and schistosome infection in snails was done by primers targeting mitochondrial sequences. Multiplex PCR was standardised for simultaneous detection of amphistome and schistosome and I. exustus DNA.