Spatiotemporal heterogeneity of Rhipicephalus microplus resistance to chemical acaricides at intra-farm level: A case study using ivermectin.

The aim of this work was to analyse the spatiotemporal heterogeneity of Rhipicephalus microplus (Canestrini, 1888) (Acari: Ixodidae) resistance to chemical acaricides at intra-farm level under different environmental (favourable and unfavourable areas for tick development) and management (different schemes of acaricides applications) conditions using ivermectin as a model. The in vitro larval immersion test (LIT) was used to determine quantitatively the levels of resistance to ivermectin in the different populations and subpopulations of R. microplus analysed.

Applicability of three indices to evaluate the reproductive capacity of Rhipicephalus microplus engorged female ticks in acaricide efficacy trials.

This study aimed to analyze the applicability of three different indices to evaluate the reproductive capacity of engorged females (RCEF). The indices, RCEF, RCEF and RCEF, were proposed as alternative to the count of the exact number of unhatched eggs and larvae in in vivo and in vitro acaricide efficacy trials that involve the use of engorged females to estimate the effect of a drug on their reproductive capacity. A comparison of the values of the reproductive efficiency index (REI) and the fertility efficiency index (FEI) of ten engorged females calculated from the count of the exact number of unhatched eggs and larvae and from the application of the proposed indices was performed.

Relationship between pharmacokinetics of fluazuron and its efficacy for controlling Rhipicephalus microplus: A comprehensive evaluation of tick drug uptake.

Relationship between fluazuron (FZN) concentrations in cattle plasma and ticks and its therapeutic efficacy percentage (EP) against Rhipicephalus microplus was analyzed. The extent of FZN uptake by ticks after its topical administration was also evaluated. Heifers, naturally infested with R.

Development and evaluation of a TaqMan® real-time PCR assay for species-specific detection of Ehrlichia canis.

The aim of this work was to develop a real-time PCR assay with a TaqMan® probe that detects a species-specific part of the 16S rDNA gene of Ehrlichia canis. Canine blood samples (n = 207), collected and tested by a conventional PCR assay within a study conducted by De Salvo et al., were simultaneously analyzed with the novel designed real-time PCR, and the results of both assays were compared.

Evaluation of the impact of successive acaricide treatments on resistance evolution in Rhipicephalus microplus populations: Monodrugs versus drug combinations.

The aim of this work was to comparatively evaluate the evolution of resistance in Rhipicephalus microplus tick populations exposed to successive treatments with monodrug-based formulations and combinations of them in the same commercial formulation. Thirty-six heifers, naturally infested with R. microplus, were divided into three groups (G) and subjected to three successive treatments, on days 0 (Nov-2021), 43 (Jan-2022) and 78 (Feb-2022), with the following formulations: I) ivermectin 3.

Analysis of sequence variations in the GABA gated chloride gene associated with resistance to fipronil in Rhipicephalus (Boophilus) microplus ticks from Argentina.

This study aimed to evaluate the sequence variations of the GABA-Cl gene of Rhipicephalus (Boophilus) microplus ticks from Argentina with different resistance levels to fipronil. Genomic DNA was obtained from engorged females (n = 50) of fipronil-susceptible and resistant tick field populations from five localities in northern Argentina. Tick populations were tested for fipronil resistance by in vitro larval packet test.

Resistance of the cattle tick Rhipicephalus (Boophilus) microplus to fluazuron in Argentina.

The aim of this work is to report the presence of resistance to fluazuron in a population of Rhipicephalus microplus in Argentina. The evidence was obtained from field and in vitro trials. In the field trial, cattle infested with ticks was treated with two commercial formulations of fluazuron.

Successive treatments with ivermectin (3.15%) to control the tick Rhipicephalus (Boophilus) microplus in cattle: Pharmacokinetic and efficacy assessment.

This study aimed to evaluate the pharmacokinetics, the potential accumulation in the body of treated animals and the efficacy of ivermectin long-acting formulation (3.15%) against the cattle tick Rhipicephalus (Boophilus) microplus in a scheme of three successive treatments. Fifteen 12-month-old heifers, naturally infested with R.

Sensitivity of Anaplasma marginale genotypes to oxytetracycline assessed by analyzing the msp1α gene in experimentally infected cattle.

The aim of this study was to evaluate the influence of the long-acting oxytetracycline (OTC) treatment on A. marginale genotypes of the isolate S1P, by analyzing the msp1α genotype based on a microsatellite (ms) and tandem repeat sequences (TRS) located at the 5´ end of the gene. DNA samples were obtained from a longitudinal study of chemosterilization; 10 2-year-old steers were experimentally infected with blood from a splenectomized calf inoculated with the A.

Neospora caninum truncated recombinant proteins formulated with liposomes and CpG-ODNs triggered a humoral immune response in cattle after immunisation and challenge.

Abortions caused by Neospora caninum are a serious problem in cattle production and require effective immunoprophylaxis. The objective of this work was to assess the humoral immune response to four recombinant (r) N. caninum antigens in cattle after immunisation and challenge.

Efficacy of long-acting oxytetracycline and imidocarb dipropionate for the chemosterilization of Anaplasma marginale in experimentally infected carrier cattle in Argentina.

The expansion of anaplasmosis to non-endemic areas in Argentina has created the need for specific treatments to eliminate Anaplasma marginale from carriers. The most recent studies have failed to chemosterilize A. marginale infections.

Validation and field evaluation of a competitive inhibition ELISA based on the recombinant protein tSAG1 to detect anti-Neospora caninum antibodies in sheep and goats.

Neospora caninum is a protozoan parasite that causes abortion and reproductive failure in small ruminants. We validated and evaluated under field conditions a competitive inhibition ELISA based on the truncated SAG1 protein (tSAG1) from N. caninum for the detection of anti-N.

Resistance of the cattle tick Rhipicephalus (Boophilus) microplus to ivermectin in Argentina.

Resistance to ivermectin in populations of the cattle tick Rhipicephalus microplus in Argentina was diagnosed in this work. The in vitro larval immersion test (LIT) was used to determine quantitatively the levels of resistance to ivermectin in different populations of R. microplus.

Evaluation of a competitive inhibition ELISA based on the recombinant protein tSAG1 to detect anti- antibodies in cattle.

is a protozoan parasite that causes abortion and important economic losses in cattle worldwide. There are no treatments or vaccines available; disease control is based on diagnosis and herd management strategies. We developed, validated, and evaluated under field conditions a competitive inhibition ELISA based on the truncated SAG1 protein (tSAG1), expressed in , and the RafNeo5 monoclonal antibody (ciELISA).

A vaccine using Anaplasma marginale subdominant type IV secretion system recombinant proteins was not protective against a virulent challenge.

Anaplasma marginale is the most prevalent tick-borne livestock pathogen with worldwide distribution. Bovine anaplasmosis is a significant threat to cattle industry. Anaplasmosis outbreaks in endemic areas are prevented via vaccination with live A.

Development and evaluation of a double-antigen sandwich ELISA to identify infected and vaccinated cattle.

Bovine anaplasmosis is a worldwide infectious disease caused by the intraerythrocytic bacterium , which is transmitted by ticks and fomites. is a less virulent subspecies used as a live vaccine in cohorts of 8- to 10-mo-old calves that did not naturally reach enzootic stability. We developed 3 variants of a double-antigen sandwich ELISA (dasELISA) using a recombinant major surface protein 5 (MSP5) from (dasELISAm) or from (dasELISAc) or using MSP5 from both organisms (dasELISAmc).

Development of a novel fusion protein with Anaplasma marginale and A. centrale MSP5 improved performance of Anaplasma antibody detection by cELISA in infected and vaccinated cattle.

Detection of antibodies to Anaplasma spp. using commercial competitive enzyme-linked immunosorbent assay (ccELISA) is based on the recombinant major surface protein 5 fused to maltose binding protein (MBP-MSP5) or glutathione S-transferase (GST-MSP5). To avoid false positive reactions due to the presence of antibodies against E.