The detection of anthelmintic resistance in nematodes of veterinary importance

The aim was to evaluate for 75 days the impact on production of the remaining burden of ivermectin (IVM)-resistant parasites in naturally infected feedlot calves. The herds came from tick-infested areas of cattle breeding where the systematic use of IVM to control tick increases the gastrointestinal parasites resistant to this drug. This investigation was carried out in two commercial feedlots in Buenos Aires province. In feedlot A, two groups of 35 animal each received IVM 1% and the other received ricobendazole (RBZ) 10% respectively. The same was done in feedlot B. On day 0, two groups of 35 animals were made in feedlots A and B. Fecal samples were taken on days 0, 22, 54 and 75 pos-treatment (PT), and body weight was registered, from each animal. Fecal samples were processed for individual count of eggs per gram (EPG) and pooled fecal culture was carried out for identiϐication of the parasite genus in each sampling. Fecal egg count reduction test (FECR) was calculated on day 22 PT. The study design used was a totally randomized block, with commercial feedlot and sex as block variables. For data analysis, a mixed model of the SAS statistical program was used. The FECR average on day 22 was 28.4% in the IVM group, and 94,2 % in the RBZ group . From this date on, signiϐicant differences in EPG were kept until day 54. EPG counts were only equal near the end of the trial, on day 75 (p=0.16). In both commercial feedlots, especially in the IVM group, Cooperia spp. was the most prevalent parasite in the fecal cultures. Signiϐicant differences in weight (P<0.01) on post-treatment day 75 was found between the average weight in the RBZ and the IVM group (246 vs. 238 kg respectively), what means a difference of 8.3% in gains. The importance for production in the antiparasite failure treatment in commercial feedlots was demonstrated, and the need of pos-treatment controls to evaluate the efϐicacy of the antiparasitic administered is emphasized.

show abstract

“…However, it did not reach the 95% considered as the efϐicacy limit to control the disease and the production loss (Coles et al 2006).…”

Section: Discussionmentioning

confidence: 96%

Impact of ivermectin-resistant gastrointestinal nematodes in feedlot cattle in Argentina

et al. 2012

View full text Add to dashboard Cite

show abstract

“…The cyclic reaction as described by Coles et al (2006) was performed with the 5 ll of the larval digest as the template in a 10.25 ll reaction mixture containing 109 Taq Buffer (without MgCl 2 ), 80 lM dNTP mix (New England Biolabs), 1.5 mM MgCl 2 (New England Biolabs), 0.5U Taq DNA polymerase (New England Biolabs), 6.5 pmol of each forward Pn1 and reverse primer Pn2. An aliquot of 1 ll of the [Pn1-Pn2] PCR product was used as a template in a reaction mixture of 25 ll containing 109 Taq Buffer (without MgCl 2 ), 80 lM dNTP mix(NEB), 1.5 mM MgCl 2 (NEB), 1.0 U Taq DNA polymerase (NEB), 12.5 pmol of each forward Pn3 and reverse primer Pn4.…”

Section: Amplification Of B-tubulin Gene By Nested Pcrmentioning

confidence: 99%

Genotyping of benzimidazole resistant and susceptible isolates of Haemonchus contortus from sheep by allele specific PCR

et al. 2016

View full text Add to dashboard Cite

Extensive and indiscriminate use of the benzimidazole class of drugs has led to the onset of anthelmintic resistance. In tropical countries like India, Haemonchus contortus is the most pathogenic parasite infecting sheep and goats. The widespread presence of resistant helminths (especially H. contortus) threatens the livestock farming. The use of various drugs has led to single nucleotide polymorphism that causes specific amino acid substitutions in b-tubulin protein of H. contortus to confer resistance. This emphasizes the need for a survey on the present status of resistance in India. In this study, allele specific PCR was employed to screen the presence of a SNP, a thymine-toadenine transversion which leads to substitution of amino acid in codon 200 of b-tubulin gene that is correlated specifically with BZ resistance. Third stage larvae (L3) from pooled faecal cultures of four organized sheep farms served as a source of genomic DNA for identification of H. contortus and further genotype analysis. A total of 1000 larvae was screened, out of which 673 larvae were identified as H. contortus. Among 673 H. contortus larvae, 539 larvae (80 %) were genotyped as homozygous resistant (rr) and remaining 134 (20 %) were heterozygous susceptible (Sr) by allele specific PCR. The concluded resistance status reasons out the failure of anthelmintic drug in treating ruminants. Immediate steps are needed to avoid further aggravation of the problem. Target selective treatment by reviewing the resistance status of individual drugs, appropriate use of anthelmintic drugs and other control strategies will provide a pragmatic option for delaying the further spread of anthelmintic resistance.

show abstract

“…For example, it is known that the immature stages of some T. circumcincta populations are refractory to levamisole treatment (Grimshaw et al, 1996), which is the basis for conducting faecal egg count reduction tests (FECRT) on day 7 post-treatment (Coles et al, 2006). Under these circumstances levamisole treatments may inadvertently maintain refugia.…”

Section: Sources Of Refugiamentioning

confidence: 99%

The role of targeted selective treatments in the development of refugia-based approaches to the control of gastrointestinal nematodes of small ruminants

Kenyon

Greer

Coles

et al. 2009

Veterinary Parasitology

Self Cite

234

138

View full text Add to dashboard Cite

The detection of anthelmintic resistance in nematodes of veterinary importance

Cited by 791 publications

References 62 publications

Impact of ivermectin-resistant gastrointestinal nematodes in feedlot cattle in Argentina

Impact of ivermectin-resistant gastrointestinal nematodes in feedlot cattle in Argentina

Genotyping of benzimidazole resistant and susceptible isolates of Haemonchus contortus from sheep by allele specific PCR

The role of targeted selective treatments in the development of refugia-based approaches to the control of gastrointestinal nematodes of small ruminants

Contact Info

Product

Resources

About