Evaluation of clinical signs, parasitemia, hematologic and biochemical changes in cattle experimentally infected with Trypanosoma vivax

Abstract

Infections by Trypanosoma vivax cause great losses to livestock in Africa and Central and South Americas. Outbreaks due this parasite have been occurred with increasing frequency in Brazil. Knowledge of changes caused by T. vivax during the course of this disease can be of great diagnostic value. Thus, clinical signs, parasitemia, hematologic and biochemical changes of cattle experimentally infected by this hemoparasite were evaluated. Two distinct phases were verified during the infection -an acute phase where circulating parasites were seen and then a chronic phase where fluctuations in parasitemia were detected including aparasitemic periods. A constant reduction in erythrocytes, hemoglobin and packed cell volume (PVC) were observed. White blood cells (WBC) showed pronounced changes such as severe neutropenia and lymphopenia during the acute phase of the illness. Decreases in cholesterol, albumin, aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and increases in glucose, globulin, protein, and alkaline phosphatase (ALP) were observed. The "Lins" isolate of T. vivax showed pathogenicity for cattle, and intense parasitemia was detected in the early stages of infection. Circulating parasites were detected for about two months. The most evident laboratory abnormalities were found in WBC parameters, including thrombocytopenia.Keywords: Trypanosomiasis, bovine, host-parasite relationship, complete blood count. ResumoInfecções pelo Trypanosoma vivax causam grandes prejuízos à pecuária na África e Américas Central e do Sul. Surtos devido a este protozoário têm ocorrido com frequência cada vez maior no Brasil. O conhecimento das alterações provocadas pelo T. vivax durante a evolução desta enfermidade podem ser de grande valia para o auxílio no diagnóstico. Para tanto foram estudados os sinais clínicos, parasitemia, alterações hematológicas e bioquímicas em bovinos experimentalmente infectados por este hemoparasito. Foram verificadas duas fases distintas durante a infecção, uma aguda onde parasitos circulantes foram vistos durante todo o período, e posteriormente uma crônica, onde foram detectadas flutuações na parasitemia, com períodos aparasitêmicos. Foi verificada constante diminuição da contagem global de eritrócitos, teor de hemoglobina e volume globular (VG). O leucograma revelou leucopenia por neutropenia e linfopenia durante a fase aguda da enfermidade. Foram observados diminuição do colesterol, albumina, aspartato aminotransferase (AST), lactato desidrogenase (LDH) e aumento da glicose, globulinas, proteínas e fosfatase alcalina (FA). O isolado "Lins" de T. vivax apresentou patogenicidade para bovinos, verificando-se parasitemia intensa nos estágios iniciais da infecção, sendo detectados parasitas circulantes por aproximadamente dois meses. As alterações laboratoriais mais evidentes foram encontradas nos parâmetros do leucograma, ainda destacando-se um quadro de trombocitopenia.Palavras-chave: Tripanossomíase, bovino, relação parasita-hospedeiro, hemograma.

Comparison of conventional and molecular techniques for Trypanosoma vivax diagnosis in experimentally infected cattle

“…Through qPCR analysis it was possible to verify that the patent phase of the illness, where parasites can be detected without interruption, may extend up to 42 DAI. This is well beyond the 14 DAI and 30 DAI previously reported by Rodrigues et al (2013) and Fidelis et al (2016), respectively, which used direct parasitological techniques to quantify the parasitaemia. Thus, the use of more sensitive molecular tool may help in a better understanding of the parasite dynamics during the infection.…”

“…The present experiment was approved by the Animal Ethics Committee of the São Paulo State University (Unesp) School of Agricultural and Veterinarian Sciences under the process number 13219/15. Three Girolando cows aged six to seven years were experimentally infected via the intravenous route with 2.0 × 10 7 trypomastigotes of T. vivax, "Lins" isolate (CADIOLI et al, 2012;GARCIA et al, 2014), being this a complementary work to the study developed by Fidelis et al (2016). Blood sampling of each animal occurred seven day before inoculation (-7 DAI), on the day of inoculation (0 DAI), the day after inoculation (1 DAI) and then weekly till 119 days after infection (DAI).…”

“…In cattle, T. vivax diagnosis is difficult, since the parasite triggers non-specific symptoms such as fever, anorexia, weight loss, reduced milk production, abortions, and neurological signs (BATISTA et al, 2007;CADIOLI et al, 2012). Moreover, there are fluctuations in parasitaemia and apparently aparasitemic intervals (DESQUESNES, 2004;CADIOLI et al, 2015;FIDELIS et al, 2016).…”

Detection and molecular characterization of Trypanosoma (Duttonella) vivax in dairy cattle in the state of Sergipe, northeastern Brazil

“…Although infection due to T. (D.) vivax does not present with specific clinical signs, some signs described here are compatible with those already reported in the scientific literature (LINHARES et al, 2006;FIDELIS et al, 2016). Interestingly, one animal presented neurological signs that were consistent with reports from an outbreak of T. (D.) vivax in cattle in the Brazilian semiarid region (BATISTA et al, 2007).…”

Coxiella burnetii associated with BVDV (Bovine Viral Diarrhea Virus), BoHV (Bovine Herpesvirus), Leptospira spp., Neospora caninum, Toxoplasma gondii and Trypanosoma vivax in reproductive disorders in cattle

“…The plates (Nunc Maxisorp  , Thermo Fisher Scientific, São Paulo -São Paulo, Brazil) sensitized with T. vivax antigen were incubated for 90 minutes at 37°C, in a moist chamber. After three washes with PBS-Tween 20 buffer, reference positive and negative sera (FIDELIS et al, 2016) and test sera were added to the ELISA plate. All serum samples were diluted 1:400 solution in PBS-Tween 20 plus 5% of skimmed milk powder (Molico  , Nestlé, São Paulo -São Paulo, Brazil).…”