High-level ivermectin resistance in a field isolate of Haemonchus contortus associated with a low level of resistance in the larval stage: implications for resistance detection

Kotze, Andrew C.; Dobson, R.J.; Tyrrell, Kerri; Stein, P.A.

doi:10.1016/s0304-4017(02)00200-5

Cited by 22 publications

(14 citation statements)

References 10 publications

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“…Several methods have been described, but reproducibility, linearity of the dose-response and susceptibility differ. In vitro anthelmintic inhibition of larval development of the freeliving stages in H. contortus was tested by more authors (Bartíková et al, 2010, Kotze et al, 2002, Le Jambre et al, 1995, Várady et al, 2007, Várady et al, 2009. Drugs such as benzimidazoles, imidazothiazoles and macrocyclic lactones show relatively good larvicidal activity in susceptible strains but they were mostly insufficient in resistant strains.…”

Section: Resultsmentioning

confidence: 99%

Efficacy of monepantel against lower developmental stages of a multi-resistant and susceptible Haemonchus contortus isolates: an in vitro study

et al. 2013

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SummaryMonepantel (MOP) belongs to a new class of anthelmintic compounds, the amino-acetonitrile derivates, which have a different mode of action as the currently used anthelmintics. Many present studies confirmed the high efficacy of MOP against fourth larval and adult stages of Haemonchus contortus. The objective of this study was to determine in vitro efficacy of MOP against lower development stages (eggs, L 1 -L 3 larvae) and to compare it between resistant and susceptible isolates of H. contortus. For this purpose, two in vitro tests -egg hatch test and micro-agar larval development test were used. Results were quantified as 50 % lethal concentration (LC 50 ), 99 % lethal concentration (LC 99 ) and resistance factor (RF). This study revealed the high efficacy against lower larval stages (L 1 -L 3 ) of both resistant and susceptible strains of this parasite. Larval susceptibility was not dependent of the sensitivity status of the nematode isolate. On the other hand, ovicidal effect of MOP was very low.

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Section: Resultsmentioning

confidence: 99%

Efficacy of monepantel against lower developmental stages of a multi-resistant and susceptible Haemonchus contortus isolates: an in vitro study

et al. 2013

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“…The initial problem with the tests was their inability to produce a complete ivermectin dose-response, which resulted in failure to detect ivermectin-resistant isolates (Coles et al, 1988;Taylor, 1990). Several authors (Rohrer et al, 1994;Várady et al, 1996;Amarante et al, 1997) noted that use of an avermectin analogue (ivermectin aglycone, eprinemectin) increased the ability of the test to differentiate between ivermectin-resistant and -susceptible isolates (Kotze et al, 2002). Previous results suggest that the LDT has been the most sensitive test for detecting ML-resistant nematodes of sheep and goats.…”

Section: Methods For Detection Of Anthelminthic Resistancementioning

confidence: 99%

Anthelmintic resistance in parasites of small ruminants: sheep versus goats

et al. 2011

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SummaryAnthelmintic resistance among parasites of sheep and goats has been known to occur for at least four decades. Both species of host have similar genera of nematodes, but the nematodes in goat herds usually develop anthelmintic resistance more rapidly. In vitro tests show higher ED 50 values in goats than in flocks of sheep. Sheep and goats differ in many ways; for example, goats have a higher metabolic rate and require higher dose rates for drugs. The immune system of goats is also different. Additionally, these animals are reared under different management systems, i.e. sheep graze pastures and goats browse bushes, and lambing/kidding periods are different. Most anthelmintics used in goats have not been licensed for this animal species, and correct dose rates have rarely been experimentally determined. Possible explanations for such differences are discussed.

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“…This is very significant for the continuation of an effective chemical control. To detect and monitor the resistance developed against anthelmintics in nemotodes, in vivo and in vitro methods have been developed (Kotze et al 2002;Taylor et al 2002). To date, the most frequently used method is the in vivo method, faecal egg count reduction test (FECR), for the detection of anthelmintic resistance.…”

Section: Introductionmentioning

confidence: 99%

The resistance of nematode parasites in sheep against anthelmintic drugs widely used in Western Turkey

et al. 2007

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This study was carried out in seven sheep herds infected by gastro-intestinal nematodes in the Afyonkarahisar district (Western Turkey) from June to July 2005. Sixty sheep in each herd were distributed into 3 groups as anthelmintic treatment groups along with a control group containing 15 animals. The anthelmintic groups were treated with albendazole (7.5 mg/kg BW), oxfendazole (7.5 mg/kg BW)-oxyclosanide (15 mg/kg BW) combination and ivermectin (0.2 mg/kg BW-injectable). The faecal samples were collected before treatment and after 10 days of treatment. Nematode egg counts per gram of faeces (EPG) were examined in the faecal samples using the McMaster technique. To identify the genus, the faecal samples were cultured. The faecal egg count reduction test (FECR) was employed to determine the resistance. In ivermectin treated groups, the FECR% values and the lower confidence limits were estimated as A: 68.57(14.77), B: 46.42(22.47), C: 84.41(35.38), D: 95.23(61.64), E: 97.14(76.94), F: 65.21(80.46) and G: 91.66(31.69), respectively. In the A, B, C, F and G herds, statistical analysis showed that the FECR% values were less then 95% and the estimated lower confidence limits were less then 90%. In all herds, albendazole treated, oxfendazole-oxyclosanide treated and control group, there were no eggs in the feacal samples. In these groups, the FECR% values were 100. In ivermectin treated groups, the third stage larvae from the genera Haemonchus, Oesophagostomum, Trichostrongylus, Cooperia, Nematodirus and Ostertagia were detected in coprocultures before treatment and the larvae from the genera Haemonchus and Oesophagostomum were detected in post-treatment coprocultures in the resistant herds. In conclusion, there was no evidence of resistance in sheep gastro-intestinal nematodes against albendazole and oxfendazole-oxyclosanide; in contrast, the resistance against ivermectin was detected in five sheep herds in the Afyonkarahisar district.

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High-level ivermectin resistance in a field isolate of Haemonchus contortus associated with a low level of resistance in the larval stage: implications for resistance detection

Cited by 22 publications

References 10 publications

Efficacy of monepantel against lower developmental stages of a multi-resistant and susceptible Haemonchus contortus isolates: an in vitro study

Efficacy of monepantel against lower developmental stages of a multi-resistant and susceptible Haemonchus contortus isolates: an in vitro study

Anthelmintic resistance in parasites of small ruminants: sheep versus goats

The resistance of nematode parasites in sheep against anthelmintic drugs widely used in Western Turkey

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