Follow-up of dairy cattle naturally infected by Trypanosoma vivax after treatment with isometamidium chloride.

Trypanosoma vivax infections cause nonspecific clinical signs in cattle associated with aparasitemic intervals, making disease diagnosis a challenge. In Brazil, diminazene aceturate and isometamidium chloride (ISM) are available to treat bovine trypanosomosis. The objective of this study was to follow-up, by molecular and serological techniques, dairy cattle naturally infected by T. vivax after ISM treatment. Thirty cattle naturally infected with T. vivax received two applications of ISM, at a dosage of 1.0 mg/kg intramuscularly, on days 0 and 150. For T. vivax diagnosis, EDTA-blood and serum samples were evaluated on 0, 7, 15, 30, 60, 90, 120, 150, 180, 210, and 240 days after treatment PCR, Loop-mediated isothermal amplification (LAMP) and ELISA. Animals with persistent detection of T. vivax DNA by both PCR and LAMP were found and continuous detection of anti-T. vivax IgG antibodies by ELISA, suggesting the presence of T. vivax resistance to ISM. The combination of LAMP and ELISA tests can prevent misdiagnosis of the parasite clearance in treated cattle, contributing to better disease control. This is the first experiment that demonstrates the persistence infection of T. vivax under ISM treatment in a natural infected herd and evidence of ISM chemotherapy-resistant T. vivax in Brazil.

Follow-up of dairy cattle naturally infected by Trypanosoma vivax after treatment with isometamidium chloride / Acompanhamento de bovinos leiteiros naturalmente infectados com Trypanosoma vivax após tratamento com cloreto de isometamidium

Abstract Trypanosoma vivax infections cause nonspecific clinical signs in cattle associated with aparasitemic intervals, making disease diagnosis a challenge. In Brazil, diminazene aceturate and isometamidium chloride (ISM) are available to treat bovine trypanosomosis. The objective of this study was to follow-up, by molecular and serological techniques, dairy cattle naturally infected by T. vivax after ISM treatment. Thirty cattle naturally infected with T. vivax received two applications of ISM, at a dosage of 1.0 mg/kg intramuscularly, on days 0 and 150. For T. vivax diagnosis, EDTA-blood and serum samples were evaluated on 0, 7, 15, 30, 60, 90, 120, 150, 180, 210, and 240 days after treatment PCR, Loop-mediated isothermal amplification (LAMP) and ELISA. Animals with persistent detection of T. vivax DNA by both PCR and LAMP were found and continuous detection of anti-T. vivax IgG antibodies by ELISA, suggesting the presence of T. vivax resistance to ISM. The combination of LAMP and ELISA tests can prevent misdiagnosis of the parasite clearance in treated cattle, contributing to better disease control. This is the first experiment that demonstrates the persistence infection of T. vivax under ISM treatment in a natural infected herd and evidence of ISM chemotherapy-resistant T. vivax in Brazil.

Resumo Em bovinos, infecções por Trypanosoma vivax geram sinais clínicos inespecíficos que, associados a intervalos aparasitêmicos, faz com que o diagnóstico da enfermidade seja desafiador. No Brasil, somente aceturato de diaminazeno e cloridrato de isometamidum (ISM) estão disponíveis para o tratamento da tripanossomose bovina. Este trabalho teve como objetivo acompanhar bovinos leiteiros naturalmente infectados por T. vivax, após o tratamento com ISM por meio de técnicas moleculares e sorológica. Foram utilizados 30 bovinos naturalmente infectados com T. vivax, sendo estes tratados com duas aplicações de ISM, na dosagem de 1,0 mg/kg por via intramuscular profunda, nos dias 0 e 150. Foram avaliadas, para diagnóstico de T. vivax, amostras de sangue acrescido de EDTA e soro, colhidas nos 0, 7, 15, 30, 60, 90, 120, 150, 180, 210 e 240 dias após os tratamentos pela reação em cadeia da polimerase (PCR), amplificação circular isotérmica do DNA (LAMP) e ensaio de imunoabsorção enzimático (ELISA). Verificou-se a presença de animais com persistência na detecção de DNA de T. vivax pela PCR e LAMP, bem como detecção contínua de anticorpos IgG anti-T. vivax pelo método de ELISA, sugerindo a presença de resistência de T. vivax ao ISM. A combinação dos testes LAMP e ELISA pode evitar falsos diagnósticos da eliminação do parasita nos bovinos tratados, contribuindo para um melhor controle da doença. Este é o primeiro experimento que demonstra infecção persistente do T. vivax em rebanho naturalmente infectado, tratado com ISM, e evidencia possível resistência ao quimioterápico no Brasil.