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

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.

Evaluation of techniques for diagnosis of Trypanosoma vivax infections in naturally infected cattle in the Zona da Mata Mineira

“…In naturally infected animals, the kappa index found, of 0.67, for Woo technique and a whole blood smear was considered substantial (Fidelis et al, However, ELISA and PCR did not reach an agreement, presenting a kappa index of -0.0137. This result is in agreement with that found by Castilho et al (2021), who pointed out a kappa index of -0.02 when comparing the ELISA and PCR diagnostic tools. These findings are because the techniques in question are based on different assumptions and detection targets, reiterating the need to associate serological and molecular tools for the diagnosis of T. vivax in naturally infected herds (Castilho et al, 2021).…”

“…In addition, this serological technique has limitations for identifying antibodies during the first days of infection (Fidelis et al, 2019). These results highlight the importance of using high-sensitivity techniques such as ELISA in naturally infected animals to avoid further spreading of the parasitic infection due to a lack of effective diagnostic methods (Castilho et al, 2021).…”

“…Serological tests such as ELISA can detect anti-T. vivax antibodies circulating for long periods in untreated animals, including animals treated with non-specific anti-Trypanosoma drugs (Fidelis et al, 2019). Thus, it constitutes an important tool to assess the epidemiological status of the herd (Osório et al, 2008;Cuglovici et al, 2010), although it is not the most suitable for differentiating individuals with active infection from those undergoing treatment or spontaneously cured (Cadioli et al, 2012;Castilho et al, 2021). In addition, this serological technique has limitations for identifying antibodies during the first days of infection (Fidelis et al, 2019).…”

Detection of Trypanosoma vivax in tissues of experimentally infected goats: what is the role of adipose tissue in the life cycle of this protozoon?

“…Relapses of T. vivax infection after treatment with trypanocidal drugs such as diminazene diaceturate (DA) and isometamidium chloride (ISM) have been reported (Schönefeld et al, 1987;Cadioli et al, 2012;Bastos et al, 2017;Castilho et al, 2021). Despite some authors had suggested that T. vivax resistance to the drug is caused due to indiscriminate use, underdosing and formulations with inadequate chemotherapy concentrations (Schönefeld et al, 1987;Dagnachew & Bezie, 2015;Tekle et al, 2018), it is also possible that the parasite is able to escape from trypanocide drugs by invading host tissues in which the drug does not reach levels high enough to eliminate it (Batista et al, 2011;Bastos et al, 2020;Castilho et al, 2021). In the latter scenario, after the half-life of the trypanocide drugs has expired, the parasites may leave their "refuge sites" and returns to the host's bloodstream.…”

“…In Brazil, DA and ISM are the only two trypanocide drugs licensed by the Ministry of Agriculture, Livestock and Supply (MAPA). They are generally used against T. vivax infection (Castilho et al, 2021). These drugs have half-lives of approximately 4.5 and 12 days, respectively (Eisler, 1996;Kaur et al, 2000).…”