Studies on Epidemiology, Hematobiochemistry and Seroprevalence of Piroplasmosis in Horses
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Date
2015
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AAU, Anand
Abstract
Horses (Equus caballus) belong to the family Equidae. Equine demography of India reveals 41% population distribution of horses and ponies and 59% of mules and donkeys. Total Indian equine population is 1.77 million (NRCE, 2011), which includes defined Indian horse breeds and Non-descript horses. Equine piroplasmosis caused by Theileria equi and Babesia caballi is an economically important hemoprotozoan disease of horses in tropical and subtropical parts of the worid. In 1976, the equine piroplasmosis was reported in an outbreak form in imported horses and recorded 50.1%) and 49.76% incidence in North-West India by CAT & Dot-ELISA. National serosurveillance analysis at NRCE has revealed 28.58%) of overall seroprevalence of T. equi from India. The latent infection is common in non-descript equids of India. These animals act as nucleus for maintaining as well as spreading the infection through vector ticks. Thus the diagnosis of sub-clinical infection is of more relevance as these animals can remain carriers to the T. equi parasite throughout their life span. These latently infected animals may exhibit low performance following physical, immunological or mental stress due to the flare-up of underlying parasitemia leading to clinical form of the disease condition. In the present study, total 248 horses were studied for T. equi and 182 serum samples of horses were screened for B. caballi. The overall prevalence rate of T. equi was 12.09% as detected by PCR technique. The overall prevalence rate of B. caballi was 0.55% as detected by cELISA. The breed-wise prevalence of T. equi infection observed was 23.81% in Nondescript breeds, 15.91%) in Kathiawari breeds and 11.40%) in Marwari breeds. The breed-wise prevalence was found to be statistically non-significant. The age-wise prevalence of T. equi infection observed was 33.33%) in foals, 18.52%) in yearlings and 13.42% in adults. The age-wise prevalence was found highly significant. The difference in sex-wise prevalence of T. equi infection observed were 22.86%) in males and 10.77% in females. The sex-wise prevalence was found to be highly significant. The health condition-wise prevalence of T. equi infection observed in horses were 11.85%) in good health condition, 21.82%) in fair health condition and 20%o in poor health condition%. The difference in health condition-wise prevalence was found be statistically nonsignificant (P>0.05). The diagnosis of piroplasmosis remains a challenge since the parasitemia; was often very low and there was fluctuation in the clinical symptoms shown by the affected horses. The PCR, which is a molecular technique is more sensitive than parasitological method detected an overall prevalence rate of 12.1%. The competitive ELISA, which is a monoclonal antibody based and highly sensitive and specific test detected 0.55% prevalence rate of 5. caballi in horses. Out of 248 thin blood smears examined by using Giemsa staining technique, only 5 were found to be positive indicating a prevalence rate of 2.02% and the same was found to have low sensitivity compared to PCR which detected 12.1% prevalence. Clinical information including vital signs were also recorded. Most of the horses positive for T. equi had anorexia, colic, rhinotaxis, respiratory distress, lameness. abortion, presence of ticks, fever or pyrexia, tachycardia, tachypnoea, pale or icteric mucous membrane, depression, edema of hind Hmbs, cohc, nasal discharge, ocular discharge, lameness, dyspnoea and previous history of treatment against piroplasms. In the present study, hemato-biochemical analysis of infected as well as healthy horses was performed to find out the severity of disease and probable outcome of diseases. In case of T. equi infection, TLC and Granulocytes were significantly increased (P<0.05) infected horses, while lymphocytes, Hb, MCH and PLT significantly decreased (P<0.01) compared to the healthy group of horses. A significant reduction (P<0.05) in RBC was also observed in infected group indicating anemia. A non-significant reduction (P>0.05) in MCHC and MCV as well as non-significant elevation (P>0.05) in PCV was also observed in infected group when compared to the healthy group. In case of T. equi infection, SGPT, SOOT, GOT, Total protein, Globulin, BUN, Creatinine and LDH were significantly increased (P<0.01) compared to the healthy group of horses. Non-significant elevation (P>0.05) of total bilirubin, unconjugated bilirubin and glucose as well as non-significant reduction (P>0.05) of conjugated bilirubin, albumin and A/G ratio was also observed in infected group. There was no significant alteration (P>0.05) in the levels of serum calcium and phosphorus when compared to the healthy group. In case of horses positive for T. equi, there was significant increase (P<0.05) in Cortisol and T4 level. But there was significant reduction (P<0.01) in infected horses when compared to the healthy group. The Cortisol level was significantly higher (P<0.05) in Kathiawari breeds compared to Marwari and Non-descript breeds. The Cortisol level of T. equi infected horses revealed significant reduction (P<0.05) in Kathiawari breeds whereas significant elevation (P<0.05) in Non-descript breeds. T3 concentration in Marwari breeds was found to be significantly decreased (P<0.01) whereas T4 level significantly increased in Non-descript breeds. There was no significant alteration in Cortisol, T3 and T4 level of T. equi infected horses of male and female groups when compared to the healthy group. Diagnosis of subclinical infections is important to prevent spread of equine piroplasmosis. Priority should be given for the development and validation of highly sensitive, simple and specific parasitological, serological or nucleic acid based diagnostic tool to distinguish infected and non-infected horses.
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VETERINARY MEDICINE, A STUDY