Oestrus ovis: sintomatologia, perdas produtivas, profilaxia e diagnóstico da oestrose em cordeiros naturalmente infestados
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Data
2022-05-19
Autores
Bello, Hornblenda Joaquina Silva
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Universidade Estadual Paulista (Unesp)
Resumo
Em experimento inicial, os efeitos profiláticos e terapêuticos de ivermectina e closantel foram avaliados em cordeiros com infestação natural de O. ovis. O ensaio foi realizado entre o início de Dezembro de 2019 e Março de 2020, com 30 cordeiros machos distribuídos em três grupos de 10 animais cada: controle (sem tratamento), tratado com ivermectina (0,2 mg/kg, via subcutâneo) e tratado com closantel (10 mg/kg, via oral). Os grupos foram tratados em duas ocasiões com 70 dias de intervalo: em 5 de Dezembro de 2019 e em 13 de Fevereiro de 2020. Em 19 de Março de 2020, todos os ovinos foram abatidos. As cabeças dos cordeiros foram retiradas e seccionadas ao longo do seu eixo longitudinal e sagital para recuperação das larvas. As larvas recuperadas de O. ovis foram contadas e identificadas de acordo com o seu estádio de desenvolvimento (L1, L2 e L3). Sete dos cordeiros do grupo controle estavam infestados com larvas de O. ovis entre seis e 17 larvas. Todas as larvas recuperadas do grupo controle estavam intactas e ativas. Três animais tratados com ivermectina tinham larvas de O. ovis (1 a 3 larvas), contudo estavam mortas. Os animais tratados com closantel não tinham quaisquer larvas. Os sinais clínicos sugestivos de oestrose foram escassos durante o período experimental. As médias de ganho de peso diário foram semelhantes (p > 0,05) entre os grupos. Closantel e ivermectina tiveram alta eficácia contra a oestrose e o parasitismo por O. ovis não prejudicou o desempenho dos cordeiros. Um segundo experimento com cordeiros, naturalmente infestadas por larvas de O. ovis, foi realizado com o objetivo de avaliar a variabilidade dos sinais clínicos de oestrose e a adequação da PCR e ELISA como método de diagnóstico. O experimento foi realizado de Dezembro de 2020 a Abril de 2021 com 39 animais divididos em dois grupos: grupo infestado (n=26) e grupo controle tratado (n=13). O grupo infestado não recebeu tratamento contra a oestrose, e o grupo controle foi tratado com closantel (10 mg/kg, via oral), a cada 28 dias, a fim de manter os animais tão livres, quanto possível, da infestação por O. ovis. Os sinais clínicos variavam entre os animais independentemente do número de larvas recuperadas, no entanto, os escores de secreção nasal mucosa espessa e de mucopurulenta eram menos frequentes nos ovinos do grupo tratado. Não houve correlação entre o escore de descarga nasal e o número de larvas recuperadas de O. ovis (R² = 0,012, P = 0,165). Três animais tratados apresentaram larvas de primeiro estádio (L1) (1 - 4 larvas/animal) as quais eram menores do que as L1 encontradas nos cordeiros do grupo infestado. Noventa e dois por cento dos cordeiros do grupo infestado (24/26) estavam parasitados por larvas de O. ovis (número variando de 1 a 54 larvas por animal). Foi observado um aumento gradual dos níveis de IgG plasmático (anti-antígeno das larvas de O. ovis) nos animais do grupo infestado enquanto que os ovinos do grupo controle apresentaram níveis baixos de IgG ao longo do experimento. A PCR teve baixa sensibilidade (26%) e alta especificidade (100%), e apresentou leve concordância (k = 0,177) com a detecção das larvas após o abate dos cordeiros. Os sinais clínicos de oestrose não tiveram relação com a intensidade de infestação e o ELISA mostrou-se superior em comparação com a técnica de PCR para a identificação de animais parasitados por O. ovis.
In an initial experiment, the prophylactic and therapeutic effects of ivermectin and closantel were evaluated in lambs with natural O. ovis infestation. The trial was conducted between early December 2019 and March 2020 with 30 male lambs distributed into three groups of 10 animals each: control (no treatment), treated with ivermectin (0.2 mg/kg, subcutaneously) and treated with closantel (10 mg/kg, orally). The groups were treated on two occasions 70 days apart: on December 5th, 2019 and on February 13th, 2020. On March 19th, 2020, all lambs were slaughtered. The heads of the lambs were removed and sectioned along their longitudinal and sagittal axis to larval recovery. The recovered O. ovis larvae were counted and identified according to their stage of development (L1, L2 and L3). Seven of the lambs in the control group were infested with O. ovis larvae, ranging from six to 17 larvae. All larvae recovered from the control group were intact and active. Three animals treated with ivermectin had O. ovis larvae (1 to 3 larvae), however they were dead. The animals treated with closantel did not have any larvae. Clinical signs suggestive of oestrosis were scarce during the experimental period. The mean daily weight gain was similar (p> 0.05) among the groups. Closantel and ivermectin had high efficacy against oestrosis and O. ovis parasitism did not impair lamb performance. A second experiment with lambs, naturally infested with O. ovis larvae, was performed to evaluate the variability of clinical signs of oestrosis and the suitability of PCR and ELISA as a diagnostic method. The experiment was conducted from December 2020 to April 2021 with 39 animals divided into two groups: infested group (n=26) and treated control group (n=13). The infested group received no treatment against oestrosis, and the control group was treated with closantel (10 mg/kg, orally) every 28 days in order to keep the animals as free as possible from O. ovis infestation. Clinical signs varied among animals regardless of the number of larvae recovered, however, thick mucus and mucopurulent nasal discharge scores were less frequent in sheep in the treated group. There was no correlation between nasal discharge score and the number of recovered O. ovis larvae (R² = 0.012, P = 0.165). Three treated animals had first instar (L1) larvae (1 - 4 larvae/animal), which were smaller than the L1 found in the lambs of the infested group. Ninety-two percent of the lambs in the infested group (24/26) were parasitized by O. ovis larvae (number ranging from 1 to 54 larvae per animal). A gradual increase in plasma IgG (anti-antigen of O. ovis larvae) levels was observed in the animals of the infested group, while the control sheep showed low IgG levels even throughout the experiment. PCR had low sensitivity (26%) and high specificity (100%), and showed slight agreement (k = 0.177) with the detection of the larvae after the lambs were slaughtered. The clinical signs of oestrosis were not related to the intensity of infestation, and the ELISA was superior compared to the PCR technique for the identification of O. ovis parasitized animals.
In an initial experiment, the prophylactic and therapeutic effects of ivermectin and closantel were evaluated in lambs with natural O. ovis infestation. The trial was conducted between early December 2019 and March 2020 with 30 male lambs distributed into three groups of 10 animals each: control (no treatment), treated with ivermectin (0.2 mg/kg, subcutaneously) and treated with closantel (10 mg/kg, orally). The groups were treated on two occasions 70 days apart: on December 5th, 2019 and on February 13th, 2020. On March 19th, 2020, all lambs were slaughtered. The heads of the lambs were removed and sectioned along their longitudinal and sagittal axis to larval recovery. The recovered O. ovis larvae were counted and identified according to their stage of development (L1, L2 and L3). Seven of the lambs in the control group were infested with O. ovis larvae, ranging from six to 17 larvae. All larvae recovered from the control group were intact and active. Three animals treated with ivermectin had O. ovis larvae (1 to 3 larvae), however they were dead. The animals treated with closantel did not have any larvae. Clinical signs suggestive of oestrosis were scarce during the experimental period. The mean daily weight gain was similar (p> 0.05) among the groups. Closantel and ivermectin had high efficacy against oestrosis and O. ovis parasitism did not impair lamb performance. A second experiment with lambs, naturally infested with O. ovis larvae, was performed to evaluate the variability of clinical signs of oestrosis and the suitability of PCR and ELISA as a diagnostic method. The experiment was conducted from December 2020 to April 2021 with 39 animals divided into two groups: infested group (n=26) and treated control group (n=13). The infested group received no treatment against oestrosis, and the control group was treated with closantel (10 mg/kg, orally) every 28 days in order to keep the animals as free as possible from O. ovis infestation. Clinical signs varied among animals regardless of the number of larvae recovered, however, thick mucus and mucopurulent nasal discharge scores were less frequent in sheep in the treated group. There was no correlation between nasal discharge score and the number of recovered O. ovis larvae (R² = 0.012, P = 0.165). Three treated animals had first instar (L1) larvae (1 - 4 larvae/animal), which were smaller than the L1 found in the lambs of the infested group. Ninety-two percent of the lambs in the infested group (24/26) were parasitized by O. ovis larvae (number ranging from 1 to 54 larvae per animal). A gradual increase in plasma IgG (anti-antigen of O. ovis larvae) levels was observed in the animals of the infested group, while the control sheep showed low IgG levels even throughout the experiment. PCR had low sensitivity (26%) and high specificity (100%), and showed slight agreement (k = 0.177) with the detection of the larvae after the lambs were slaughtered. The clinical signs of oestrosis were not related to the intensity of infestation, and the ELISA was superior compared to the PCR technique for the identification of O. ovis parasitized animals.
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Palavras-chave
Antiparasitário, ELISA, Oestridae, Ovino, PCR, Antiparasitic, Oestridae, Sheep