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  1. Article ; Online: Evaluation of mechanical transmission of Trypanosoma vivax by Stomoxys calcitrans in a region without a cyclic vector.

    Heller, Luciana Maffini / Bastos, Thiago de Souza Azeredo / Zapa, Dina María Beltrán / de Morais, Igor Maciel Lopes / Salvador, Vanessa Ferreira / Leal, Luccas Lourenzzo Lima Lins / Couto, Luiz Fellipe Monteiro / Neves, Lucianne Cardoso / de Freitas Paula, Warley Vieira / Ferreira, Lorena Lopes / de Barros, Antonio Thadeu Medeiros / Cançado, Paulo Henrique Duarte / Machado, Rosangela Zacarias / Soares, Vando Edésio / Cadioli, Fabiano Antonio / da Silva Krawczak, Felipe / Zanetti Lopes, Welber Daniel

    Parasitology research

    2024  Volume 123, Issue 1, Page(s) 96

    Abstract: This work investigated the mechanical transmission of Trypanosoma vivax by Stomoxys calcitrans to cattle in a region without a cyclic vector. The study involved two experiments, one with calves experimentally infected with T. vivax, in the acute phase of ...

    Abstract This work investigated the mechanical transmission of Trypanosoma vivax by Stomoxys calcitrans to cattle in a region without a cyclic vector. The study involved two experiments, one with calves experimentally infected with T. vivax, in the acute phase of trypanosomosis (Experiment 1) and the other in the chronic phase (Experiment 2). In both experiments, two transmission methods were used with flies that had not fed for 24 h or had never fed: (i) Method 1: flies released freely in cattle pens (≈3,300 flies/pen for 10 days); and (ii) Method 2: flies placed in a feeding chamber (12 flies/animal). To develop Method 1 in the two experiments (acute and chronic phases), T. vivax-positive animals were kept with T. vivax-negative animals. Periodically, the Brener method, Woo method, blood smears, cPCR, ELISA, IFAT, and Imunoteste® were performed to detect T. vivax in the animals. We also recorded the animals' head tossing and hoof stomping and the number of flies near the pens' inner walls. Subsequently, biological testing was performed using lambs. For Method 2 in both experiments, flies inside the feeding chamber first fed on T. vivax-positive animals and later on negative animals. In both experiments and methods, we examined the flies for the presence of T. vivax through blood smears and cPCR of the proboscis and abdomen. In Experiment 2 (chronic phase), a test was conducted to determine how long trypomastigotes forms could survive on the blood of animals with different levels of parasitemia. None of the animals (calves and lambs) became infected with T. vivax or showed antibodies against it. During the evaluation period, the animals in the presence of the flies exhibited more hoof stomping and head tossing compared to those without flies (control). Additionally, there was an increase in the number of flies in the pens during the experiment. Only in Experiment 1 (acute phase) were T. vivax trypomastigotes and DNA found in the abdomen of the flies but not in the proboscis. In Experiment 2 (chronic phase), higher concentrations of trypomastigotes per milliliter of blood were associated with a shorter the lifespan of this stage of the parasite. In conclusion, under the variable conditions of the experiments (hosts, number of flies, and level of parasitemia), S. calcitrans was unable to mechanically transmit T. vivax to cattle.
    MeSH term(s) Animals ; Sheep ; Cattle ; Muscidae ; Trypanosoma vivax ; Parasitemia ; Sheep, Domestic ; Antibodies
    Chemical Substances Antibodies
    Language English
    Publishing date 2024-01-15
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 284966-5
    ISSN 1432-1955 ; 0932-0113 ; 0044-3255
    ISSN (online) 1432-1955
    ISSN 0932-0113 ; 0044-3255
    DOI 10.1007/s00436-023-08102-z
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Enzootic stability of tick fever in Holstein calves grazing in a tropical region, subjected to strategic cattle tick control with fluralaner.

    Zapa, Dina Maria Beltran / de Aquino, Lidia Mendes / Couto, Luiz Felipe Monteiro / Heller, Luciana Maffini / de Morais, Igor Maciel Lopes / Salvador, Vanessa Ferreira / Leal, Luccas Lourenzzo Lima Lins / Trindade, Artur Siqueira Nunes / de Freitas Paula, Warley Vieira / de Lima, Nicolas Jalowitzki / Ferreira, Lorena Lopes / de Castro Rodrigues, Daniel / Strydom, Tom / Torres, Siddhartha / Soares, Vando Edésio / de Oliveira Monteiro, Caio Marcio / da Silva Krawczak, Felipe / Lopes, Welber Daniel Zanetti

    Parasites & vectors

    2024  Volume 17, Issue 1, Page(s) 120

    Abstract: Background: In 2022, fluralaner was launched on the market for use in the control of the cattle tick Rhipicephalus microplus after showing 100% efficacy in registration trials against the causative agents of cattle tick fever (TFAs). The aim of the ... ...

    Abstract Background: In 2022, fluralaner was launched on the market for use in the control of the cattle tick Rhipicephalus microplus after showing 100% efficacy in registration trials against the causative agents of cattle tick fever (TFAs). The aim of the present study was to determine whether a strategic control regimen against R. microplus using fluralaner (FLU) in Holstein calves grazing in a tropical region would alter the enzootic stability status of cattle tick fever, triggering outbreaks in these animals up to 22 months age.
    Methods: In this study, a group of calves treated with FLU was compared with a control group treated with the regimen currently being used on the farm, which consisted of the fipronil + fluazuron formulation (FIFLUA). In the first experiment, the efficacy of the FIFLUA pour-on formulation was evaluated in a field study. In the second experiment, which lasted 550 days, two experimental groups (n = 30/group) of Holstein calves naturally infested with R. microplus were analyzed. Calves aged 4 to 10 months received either a specific treatment regimen with FLU (experimental group) or FIFLUA (control group). During this period, tick counts, animal weight measurement, feces collection (to determine eggs and oocysts per gram of feces), tick fever monitoring, blood smears (to ascertain enzootic stability of the herd), PCR testing for TFAs and serology (indirect enzyme-linked immunosorbent assay [iELISA]) were performed. All calves were evaluated for signs of tick fever between ages 11 and 22 months.
    Results: FIFLUA showed an acaricidal efficacy of > 90% from post-treatment days 14 to 35. Regarding treatments against the TFAs, the average number of treatments was similar between groups, but animals treated with FLU had a smaller reduction in packed cell volume on some of the evaluation dates of the second and third treatment against TFAs. In calves aged 10 months in the FLU group, B. bovis was not detected by PCR (0/15 samples), 40% of the samples had antibody titers and 33% (10/30) of the samples had positive blood smears. Regarding B. bigemina, > 86% of the samples in both groups tested positive for B. bigemina DNA and antibodies; there was no difference in the antibody titers between the groups. There were no clinical cases of cattle tick fever in calves aged 11 to 22 months.
    Conclusions: In comparison with the control treatment, the strategic control regimen against R. microplus with FLU that was implemented in the present study did not negatively affect the enzootic stability status of A. marginale and B. bigemina in the herd up to 22 months of age. The enzootic stability status of B. bovis was not reached by either group. These results likely represent a characteristic of the local tick population, so further studies should be performed.
    MeSH term(s) Animals ; Cattle ; Tick Control ; Tick Infestations/drug therapy ; Tick Infestations/prevention & control ; Tick Infestations/veterinary ; Cattle Diseases/epidemiology ; Ovum ; Babesiosis/epidemiology ; Anaplasmosis/epidemiology ; Rhipicephalus ; Isoxazoles
    Chemical Substances A1443 compound ; Isoxazoles
    Language English
    Publishing date 2024-03-10
    Publishing country England
    Document type Journal Article
    ZDB-ID 2409480-8
    ISSN 1756-3305 ; 1756-3305
    ISSN (online) 1756-3305
    ISSN 1756-3305
    DOI 10.1186/s13071-024-06212-w
    Database MEDical Literature Analysis and Retrieval System OnLINE

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