A controlled study on gastrointestinal nematodes from two Swedish cattle farms showing field evidence of ivermectin resistance (original) (raw)
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Impact of ivermectin-resistant gastrointestinal nematodes in feedlot cattle in Argentina
Pesquisa Veterinária Brasileira, 2012
Pesq. Vet. Bras. 32(5):419-423, maio 2012 419 RESUMO.-[Impacto de nematódeos gastrointestinais ivermectina-resistentes em bovinos em conϐinamento na Argentina.] O objetivo deste trabalho foi avaliar durante 75 dias o impacto sobre a produção da carga de parasita-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)
2010
To evaluate the necessary time and to identify the differences among anthelmintics for the reduction of parasite eggs shed in feces, five groups of cattle were treated with moxidectin, ivermectin, levamisole phosphate, and albendazole sulphoxide. Levamisole promoted a reduction in egg count per gram (EPG-R) of 97.4% after 24 hours, moxidectin 98.3% after 36 hours, and albendazole sulphoxide 95.9% after 36 hours post-treatment. Cooperia spp. and Haemonchus spp. showed resistance to ivermectin. The results demonstrated that the diagnosis of parasite resistance in cattle can be based on a count of eggs per gram (EPG) carried out as soon as seven days after the treatment.
Worm burdens in cows: the effect of anthelmintic treatment on the parasite egg output
Veterinary Parasitology, 1982
. Worm burdens in cows: the effect of anthelmintic treatment on the parasite egg output. Vet. Parasitol., The effect on the nematode egg output of anthelmintic treatment with levamisole after parturition was studied in a group of 298 cows on four farms in the province of Groningen, and three farms in the province of Noord-Brabant (The Netherlands). Two faecal samples were taken, the first within 48 h post partum, and the second 14 days later. Half the number of cows were treated after the first sampling. Faecal examinations were made by culturing a fixed amount of faeces, counting the larvae, calculating an LPG (number of larvae per g of faeces) and making a larval differentiation. From the first sampling it became clear that with some exceptions egg output was generally low (mean LPG 7.9). Most of the cows (87.9%) were positive for Ostertagia spp. Of the other species, Trichostrongylus spp. were found in 47.7% of the samples and Cooperia puncatata in 30.5%. Less frequent were Bunostomum phlebotomum (13.1%), Oesophagostomum spp. (9.4%), Cooperia oncophora/surnabada (8.7%) and Haernonchus contortus (7.7%). The latter species was only found on farms in Noord-Brabant and was related to the grazing of sheep on the cattle pastures. In more than 60% of the cows in both provinces with an LPG-value above 20, C. oncophora/surnabada larvae were present, while H. contortus larvae were found in 50% of those cows in Noord-Brabant. Highest counts were generally observed in cows lactating for the first time,,but sometimes individual cows of older age showed a high egg output. The highest LPG-value found in this study was 228, in a first-lactating cow. The second sample of treated animals, 14 days after the first, showed that the LPG was significantly reduced from 7.6--1.4 (P < 0.001 ), while in the non-treated cows the reduction of the LPG was from 6.7--6.1, which proved to be not significant. However, all species seen prior to treatment were still present after treatment. 0304-4017/82/0000--0000]$02.75
Veterinary Parasitology, 2013
A three-year trial was performed in southwestern Sweden to compare animal performance and levels of parasite control in three grazing groups, each with 18-24 first-season grazing (FSG) calves in similar set-stocked pasture enclosures. These groups were subjected to: (1) no parasite control (NT), (2) monthly repeated doramectin (Dectomax ®) injections (SP), or (3) targeted selective weight gain-based anthelmintic treatments (TST) but only when individual calf performance was inferior to the average of the poorer 50% of those calves in group SP. In each year, weight and parasitological variables were measured at turnout and then at predetermined intervals for 22-24 weeks during the grazing season. The dewormed calves in group SP had a higher average weight gain at housing (range 0.39-0.61 kg/day) than those in TST (0.36-0.50 kg/day), which in turn always exceeded the NT group (0.23-0.42 kg/day). This indicates that the parasite challenge in the NT group was sufficiently high to result in production loss. However, the average cumulative faecal egg counts (FEC) at housing in NT were in the range 1271-1953 eggs per gram faeces (epg) and in TST 1221-1968 epg. In contrast, parasite eggs were rarely recorded in group SP and then only during the first two years (on average 12 and 38 epg). There were also no significant differences in FEC or serum pepsinogen levels between FSG in groups NT and TST. The animals in SP received 7 doses of doramectin each year, whereas those in TST received an average of 0.5 doses. Thus, the TST approach represented a 92% reduction in anthelmintic use. The average weight gain in animals subjected to TST was always significantly lower than in animals dewormed regularly. In addition, there were no signs of short-term selection for anthelmintic resistance in the group SP animals, despite the fairly intensive use of injectable doramectin.
Veterinary Parasitology, 2003
A three-year grazing experiment (1998)(1999)(2000) was conducted with first-season grazing cattle (FSGC) on improved pastures in central-eastern Sweden. Comparison was made between five groups with 10 calves in each group where four of these were set stocked and either (1) untreated, (2) ivermectin bolus treated, (3) subjected to biological control with the nematophagous fungus Duddingtonia flagrans, or (4) treated with a copper wire particle bolus. The fifth treatment was an evasive grazing strategy, whereby untreated calves were turned out onto pasture used by older cattle the previous year and then these calves were moved to silage aftermath in mid-July. To introduce low-levels of parasite infection to the experiment, each animal received a 'priming dose' of approximately 5000 Ostertagia ostertagi and 5000 Cooperia oncophora infective third stage larvae immediately prior to the start of the first grazing year of the trial.
Experimental cross-infections with gastrointestinal nematodes of sheep and cattle
Zeitschrift für Parasitenkunde (Berlin, Germany), 1981
Five parasite-free lambs and five parasite-free calves were infected experimentally with 20,000 third stage gastrointestinal nematode larvae cultured from faeces of sheep from five different farms. In the same way five lambs and five calves were infected with larvae cultured from faeces of calves from five different farms. Host specificity of the nematodes was determined using the following parameters: infection rate; number, size, and stage of the worms; their distribution within the gastrointestinal tract; and the onset, duration, and level of egg production. The conclusions with regard to the different species are: Almost exclusively in cattle Skrjabinagia lyrata Strongly adapted to cattle Ostertagia ostertagi More adapted to cattle than to sheep Cooperia oncophora, C. surnabada, C. punctata, Trichostrongylus longispicularis No special host preference T. axei, O. leptospicularis, S. kolchida More adapted to sheep than to cattle C. curticei, T. vitrinus, T. colubriformis, O. trifu...
Veterinary parasitology, 2018
Body weight gain (BWG) and gastrointestinal nematode challenge (GIN) were investigated in two genetically diverse groups of cattle. Thirty-two dairy calves (D=Swedish Red/Holstein) and 31 dairy×beef crosses (C=Swedish Red/Holstein×Charolais) pairwise matched by dam breed and birth dates, were monitored for ≈20 weeks on a pasture grazed by cattle in the previous year. At turn-out, animals (between 6 and 12 months age) from each genotype were either infected with 5000 third stage (L3) Ostertagia ostertagi (50%) and Cooperia oncophora (50%) larvae (H, high-exposure); or treated monthly with 0.5mg ivermectin (Noromectin, Pour-on) per kg bodyweight to remove worms ingested (L, low-exposure). Animals were weighed every fortnight and individual BWG was calculated. Faecal and blood samples were collected every four weeks throughout the experiment for nematode faecal egg counts (FEC) and larvae cultures and serum pepsinogen concentrations (SPC), respectively. Nematode eggs were observed 29 d...
The objective of this study was to evaluate the status of anthelmintic resistance (AR) in ruminants and horses in Spain. The efficacy of commonly used macrocyclic lactones (MLs) -ivermectin (IVM) and moxidectin (MOX) -was measured in sheep, cattle and horses. In addition, albendazole (ABZ) and levamisole (LEV) were evaluated in sheep and oxibendazole (OXI) and pyrantel (PYR) in horses. Efficacy was evaluated based on the difference between the arithmetic mean pre-and post-treatment faecal egg count (in cattle and horses), or compared to an untreated control group (in sheep). AR was present when the percentage reduction in egg count was <95% and the lower 95% confidence interval (CI) was <90%; if only one of these two criteria was met, the finding was recorded as suspected AR (SAR). In horses, AR-PYR and OXI was considered when the percentage reduction in egg count was ≤90% and the lower 95% CI was ≤80%. For each animal species, at least 10 study sites were selected.
International Journal for Parasitology: Drugs and Drug Resistance
A large-scale Fecal Egg Count Reduction Test (FECRT) was integrated with ITS-2 rDNA nemabiome metabarcoding to investigate anthelmintic resistance in gastrointestinal nematode (GIN) parasites in western Canadian beef cattle. The study was designed to detect anthelmintic resistance with the low fecal egg counts that typically occur in cattle in northern temperate regions. Two hundred and thirty-four auction market-derived, fallweaned steer calves coming off pasture were randomized into three groups in feedlot pens: an untreated control group, an injectable ivermectin treatment group, and an injectable ivermectin/oral fenbendazole combination treatment group. Each group was divided into six replicate pens with 13 calves per pen. Individual fecal samples were taken pre-treatment, day 14 post-treatment, and at monthly intervals for six months for strongyle egg counting and metabarcoding. Ivermectin treatment resulted in an 82.4% mean strongyle-type fecal egg count reduction (95% CI 67.8-90.4) at 14 days post-treatment, while the combination treatment was 100% effective, confirming the existence of ivermectin-resistant GIN. Nemabiome metabarcoding of third-stage larvae from coprocultures revealed an increase in the relative abundance of Cooperia oncophora, Cooperia punctata, and Haemonchus placei at 14 days post-ivermectin treatment indicating ivermectin resistance in adult worms. In contrast, Ostertagia ostertagi third-stage larvae were almost completely absent from day 14 coprocultures, indicating that adult worms of this species were not ivermectin resistant. However, there was a recrudescence of O. ostertagi third stage larvae in coprocultures at three to six months post-ivermectin treatment, which indicated ivermectin resistance in hypobiotic larvae. The calves were recruited from the auction market and, therefore, derived from multiple sources in western Canada, suggesting that ivermectin-resistant parasites, including hypobiotic O. ostertagi larvae, are likely widespread in western Canadian beef herds. This work demonstrates the value of integrating ITS-2 rDNA metabarcoding with the FECRT to enhance anthelmintic resistance detection and provide GIN species-and stage-specific information.