Authors

OA Agina¹; S Mohd Rosly²; MI Nur Mahiza³; M Ajat³; M Zamri-Saad³; H Hazilawati³;  ¹ University of Nigeria, Nsukka, Nigeria;  ² Malaysian Agricultural Research and Development Institute, Malaysia;  ³ Universiti Putra Malasyia, Malaysia

Discussion

The main aim of the study was to analyse the phylogeny of Trypanosoma evansi detected in Malaysian cattle and determine the haemato-biochemical abnormalities associated with natural T. evansi infection in cattle with high RoTat1.2VSG gene copy numbers.Blood samples were collected from randomly selected 130 cattle: 90 crossbred Kedah-Kelantan x Brahman cattle and 40 Bali cattle. These cattle were sampled from beef cattle farms in Muadzam Pahang and Kemaman, Terengganu Malaysia. Molecular detection and quantitation of RoTat1.2 VSG gene was achieved by real-time quantitative polymerase chain reaction (RT-qPCR) analysis. A curve of dissociation was generated to verify the specificity of the amplifications. The cattle were assigned into two groups namely: cattle with high RoTat1.2VSG gene copy number and clinically healthy cattle. Standard procedures were followed in the haematological and serum biochemistry analyses. A phylogenetic tree was constructed based on the partial RoTat1.2 VSG gene sequences of T. evansi and were supplemented with their respective reference sequences from GenBank. The alignment of the gene sequences was performed using ClustalW algorithm. The detection rate of Trypanosoma evansi was 4/130 (3.08%;95 CI 1.20–7.64%). Clinical signs observed in the infected cattle include anorexia, weakness, pale mucous membrane, cachexia and ocular discharge. Agar rose gel electrophoresis image showed a 151 bp band for RoTat1.2 VSG gene amplified from the infected cattle blood samples. The number of Trypanosoma parasites quantified from the cattle blood samples were between 40,396,41.43 – 65,07798.94 GC/µL. Numerous T. evansi were seen in the Giemsa-stained thin blood smears as elongated extracellular protozoan parasites. Furthermore, anisocytosis, poikilocytosis, macrocytes, and numerous echinocytes (artefacts) were evident. The haematological profile of T. evansi infected cattle with high RoTat 1.2 VSG include high mean erythrocyte fragility, low PCV, RBC count and haemoglobin concentration with erythrocytes that are larger than normal (macrocytic anaemia). Other abnormalities include high plasma proteins and icteric index, low leukocyte cell with high myelocyte, metamyelocyte and band neutrophil counts, and low monocyte count. Serum biochemistry findings include hyperkalaemia, hypernatraemia, hyperchloridaemia, hyperproteinaemia, low serum aspartate aminotransferase activity, high serum activities of alkaline phosphatase and gamma glutamyl transferase, hypoalbuminemia, hperglobulinemia, low albumin to globulin ratio and hyperbilirubunemia due to high level of unconjugated bilirubin. Serum inorganic phosphate and creatinine levels were high with a low serum urea level. Similarity analysis using nucleotide BLAST (BLASTn) showed that the amplicon sequences of T. evansi from this study (MT514513.1-MT514514.1) demonstrated 100% molecular similarit