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20111
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Subject: Veterinary Parasitology × Author: Bhattacharjee, Kanta × End date: 2016 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    STUDIES ON HAEMOPARASITIC INFECTIONS OF DOG WITH SPECIAL REFERENCE TO Dirofilaria immitis
    (Assam Agricultural University, Khanapara, Guwahati, 2011-08) Bhattacharjee, Kanta; Sarmah, P.C.
    The present research “Studies on haemoparasitic infections of dog with special reference to Dirofilaria immitis” was undertaken with a broad aim to assess by various methods the prevalence of haemoparasites in Assam of North East India, their clinical and clinicopathological significance and antigenic characterization of D. immitis. Microscopic study of Giemsa stained blood smears performed prospectively between January 2009 and December 2010 revealed a climate suited and highly enzootic situation with vector borne haemoparasites viz. Babesia gibsoni (47.16%), Ehrlichia platys (8.49%), Dirofilaria immitis (2.83%), Ehrlichia canis (2.12%), Babesia canis (1.41%), Hepatozoon canis (1.41%) and Ehrlichia ewingii (0.47%) in single or mixed infections. The prevalence was 57.31% in the hospital population comprising pet (58.03%) and working (54.54%) dogs and 63.64% in stray dog population in the prospective study against 23.19% record in the retrospective study. Clinical illness due to haemoparasites in the hospital dogs was recorded throughout the year. Variations in the infection rate due to age, breed and sex of dogs and seasons of the year were statistically non significant. Infection with Ehrlichia and Babesia were detected in dogs of all ages while in the case of D. immitis 80% positive cases were from 2-7 years age and 20% in the 8-10 years age group. Dogs below 2 years and above 10 years age were found microfilaria negative. Microscopic identity of Babesia species was confirmed in polymerase chain reaction (PCR), Indirect fluorescent antibody test (IFAT) using commercial B. canis IFA IgG antibody and B. gibsoni IFA IgG antibody Kits (Fuller Laboratories, USA) supplemented with conventional animal experimentation (sub-inoculation and splenectomy). PCR detection of B. canis and B. gibsoni in 16.36% and 3.63% respectively as single infection and 49.09% as mixed infection in tested samples was a significant finding which claimed 5.45% and 58.18% false negativity in B. gibsoni and B. canis detection respectively by microscopic method. In view of usual mixed infection found in PCR analysis detection of B. gibsoni in blood smear during field diagnosis could be considered as the biomarker of B. canis for the treatment purpose since the drug regimen against the two species are different. ELISA based commercial diagnostic kit, SNAP 3Dx (IDEXX, USA) confirming the microscopic identity of E. canis detected antibody in 32% dogs in a small group within the hospital population which was higher than the microscopic detection (2.12%). Among the hospital group the infection was found higher in working dogs than in the pet dogs. Seventy five percent E. canis seropositive dogs had E. platys inclusions as mixed infection suggesting the latter’s presence as biomarker for the former also. Haemoparasitic infection was confirmed in 57.31% cases through the assessment of parasite specific and non specific clinical symptoms. Regenerative anaemia characterized by biphagic erythrocyte sedimentation rate (ESR), appearance of nucleated erythrocyte, polychromasia, howell jolly body, thrombocytopenia with presence of giant platelets, variable leucogram usually with neutrophilia in blood smears were the prominent haematological findings in clinical babesiosis. In Ehrlichia, Hepatozoon and Dirofilaria infected clinical cases the anaemia was of non-regenerative type. Variable neutropenic leucopenia, thrombocytopenia with appearance of giant platelets, total absence or rare presence of howell jolly body, nucleated RBC and polychromasia in blood smear were the additional features specific to E. canis infection. However in mixed infection with Babesia and Ehrlichia features of regenerative anaemia were predominant. Biochemical evaluation showed wide variation leading to low albumin, elevated levels of total protein, globulin, creatinine and bilirubin. Dogs died of experimental and spontaneous babesiosis with nervine symptoms showed severe congestion, perivascular oedema with microabscess formation, neuronal degeneration in the brain tissue during histopathological examination. Enlarged heart with thickening of myocardium, right ventricular dilatation, thrombus formation in pulmonary artery and extensive areas of mild to moderate fatty changes were the pathological changes observed in heartworm positive carcasses. Antigenic analysis conducted in crude somatic male (SMA) and somatic female antigen (SFA) showed 9 and 17 clear protein bands in 12% SDS-PAGE of which 14, 20, 28 and 59 kDa protein fractions were common in both the antigens. Hyperimmune rabbit sera reacted with 3 protein bands in SMA and 5 protein bands present in SFA. Antibody ELISA performed in sera samples from hospital and stray dogs revealed 9.37% positivity at 1:50 dilution, 6.25% at 1:100 and 5.20% in 1:200 dilution. Necessity of a cost effective sensitive test to detect D. immitis during the amicrofilaraemic prepatent period was discussed.