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Kerala Veterinary and Animal Sciences University, Wayanad

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20211
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Subject: Veterinary Epidemiology and Preventive Medicine × Start date: 2020 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    MOLECULAR CHARACTERISATION OF Theileria orientalis AND CLINICO-THERAPEUTIC STUDIES OF THE INFECTION IN DAIRY CATTLE
    (COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR, 2021-02-16) K. SUDHAKAR GOUD; K. Vijayakumar
    The present study was undertaken to identify the genotypes of T. orientalis and to study the clinico-therapeutic aspects of T. orientalis infection in dairy cattle. A total of 410 cattle showing the clinical signs suggestive of theileriosis and 138 asymptomatic animals tethered adjacent to the infected cattle formed the study population. Theileria piroplasms were detected in 46.09 per cent of the clinically infected cattle and 52.17 per cent of asymptomatic cattle by light microscopy. Genus specific PCR yielded positive results in all smear positive clinically infected cattle and 40 asymptomatic cattle selected for molecular study. In species specific PCR, out of the 189 clinically infected cattle, 186 were found positive for T. orientalis and the remaining three cattle were positive for T. annulata. Among asymptomatic cattle, all 40 cases were positive for T. orientalis. Genotype specific PCR identified presence of Chitose and Buffeli genotypes of T. orientalis in both clinically infected and asymptomatic cattle. Mixed infection with Chitose and Buffeli genotypes was detected in 86.02 per cent and 87.5 per cent of the clinically infected and asymptomatic cattle tested respectively. These results indicated that majority of the dairy cattle positive for T. orientalis infection harbored mixed parasite populations bearing at least two different alleles of p32/33. None of the field samples tested was amplified by Ikeda type specific primers. Phylogenetic analysis based on MPSP gene sequences revealed that the T. orientalis isolates were comprised of additional two allelic MPSP gene types i.e. type 5 and 7, indicating that parasites with four MPSP types 1, 3, 5 and 7 were present in Kerala. The level of parasitaemia in T. orientalis infected animals ranged from 0.2 to 17.7 per cent. All the asymptomatic cattle (except five animals) that were positive for T. orientalis had less than one per cent level of parasitaemia. Breed wise distribution of cases revealed a high occurrence (54.8 per cent) of T. orientalis infection in Holstein Friesian crossbred cattle. A high occurrence (41.4 per cent) of T. orientalis infection was recorded among three to five years age group cattle. The occurrence of T. orientalis infection was highest (44.09 per cent) during monsoon. Most common clinical signs recorded in T. orientalis infected cattle were inappetance, pale mucous membrane, fever, lethargy and decreased milk production. The ticks present on T. orientalis infected animals were identified as Rhipicephalus microplus and Haemaphysalis longicornis based on morphological features. Haemato-biochemical analysis revealed significant decrease (p<0.05) in the mean total erythrocyte count, haemoglobin, volume of packed red cells, monocytes, albumin and albumin: globulin ratio in T. orientalis infected cattle compared to the control group. A significant increase (p<0.05) in the mean lymphocyte count was observed in T. orientalis infected animals compared to control group. There was no significant difference in the mean MCV, MCH, MCHC, platelet count, total leucocyte count, granulocytes, total proteins, globulins, aspartate aminotransferase, creatinine and blood urea nitrogen values between T. orientalis infected animals and healthy control animals. The evaluation of serum acute phase proteins, serum amyloid A (SAA) and haptoglobin revealed, significant decrease in the mean haptoglobin concentration in T. orientalis infected cattle compared to healthy control animals. No significant difference was observed in the mean SAA between T. orientalis infected animals and control animals. Among the different treatment regimens used, treatment with combination of buparvaquone and oxytetracycline LA was found to be effective for T. orientalis infected animals in terms of remission of clinical signs, but complete elimination of the organism was not observed in all the three treatment groups tested.