R. RADHIKATHAMILBHARATHI L. M.2023-02-202023-02-202021-11-30https://krishikosh.egranth.ac.in/handle/1/5810194116Thesis Submitted in the partial fulfillment of the requirement for the degree of Master of Veterinary Science in Veterinary ParasitologyThe proposed study was undertaken to develop copro-PCR for detection of economically important gastrointestinal strongyles in caprines. Strongylosis is an economically important nematode infection that adversely affects the goat population of small scale farmers in India. Adult strongyle worms were collected from 76 visceral organs of goats and its overall prevalence was estimated to be 43.42 per cent. Haemonchus contortus was found to be the most prevalent (61.5 per cent) followed by T. colubriformis (44 per cent) and O. columbianum (24 per cent). Hence, these strongyles were selected, as they were predominant species which cause production loss. The protocol for performing gradient PCR was standardised using adult worms with the designed primers targeting partial 5.8S and ITS-2 region of H. contortus, partial ITS-1 for O. columbianum and partial ITS-2 region was selected for amplifying T. colubriformis. The optimum annealing temperature was selected as 60.7oC and multiplex PCR was standardised using adult worm DNA samples. The minimum detection limit of adult H. contortus, O. columbianum and T. colubriformis DNA were 4.7 ag/µl, 0.31 fg/µl and 0.079 ng/µl respectively. No cross reactions were noticed among these strongyles. The sequences of these strongyles were accessed in GenBank with accession numbers. Copro-PCR was standardised to detect strongyle infections of economically important strongyles in the faecal sample with their adult DNA as positive control. Multiplex copro-PCR was standardised to detect multiple infections in faecal samples. A total of 257 faecal samples were collected randomly from various places in and around Thrissur. Various diagnostic procedures were conducted to study the occurrence of strongylosis viz., direct examination, sedimentation, floatation and coproculture. The overall prevalence of strongylosis was 70.42 per cent. Concurrent infections with Strongyloides spp. was observed in 47 (19.66 per cent), Moniezia spp. in 23 (9.62 per cent), coccidia in nine (3.76 per cent) and Trichuris spp. in four (1.67 per cent) samples. Coproculture was found to be the most specific conventional method for species identification of strongyles which could detect 69.92 per cent of infection. In coproculture also Haemonchus contortus was the predominant species (77.65 per cent), followed by T. colubriformis (17.8 per cent), O. columbianum (7.82 per cent), Bunostomum trigonocephalum (5.02 per cent) and Cooperia spp. (1.11 per cent). Fifty faecal samples were subjected to copro-PCR and multiplex copro-PCR. Sensitivity and specificity of multiplex copro-PCR with coproculture were assessed with McNemar test and it was found to be 76.9 and 90.9 per cent respectively. The area under receiver operating characteristic curve (ROC) showed 83.9 per cent which was found to be a good diagnostic predictability. Hence, it was found to be a rapid diagnostic tool for simultaneous detection of economically important strongyles in goats and can be employed in epidemiological studies. The inclusion of other primers of strongyles prevalent in that area could be effective for their strategic control.EnglishThesis