Multidrug resistance in Haemonchus contortus in sheep - can it be overcome?

	Group (n = 10)/Treatment	Mean EPG ± SD	FECR(%)
	Group (n = 10)/Treatment	Mean EPG ± SD	Cabaret and Berrag formula (2004) (5)	Kochapakdee formula (1995)(16)
Phase 1	G1 Albendazole single dose
	D0	370 ± 205	0	0
	D10	1,465 ± 1,482	0	0
	G2 Albendazole fasting dose
	D0	1,525 ± 1,212	16.90	13.70
	D10	1,317 ± 986	16.90	13.70
	G3 Albendazole divided dose
	D0	710 ± 326	0	0
	D10	1,400 ± 794	0	0
	G4 Albendazole double dose
	D0	605 ± 321	0	0
	D10	1,680 ± 1,803	0	0
	G5 Ivermectin
	D0	350 ± 345	39.97	31.50
	D10	240 ± 232	39.97	31.50
Phase 2	Levasmisole
	D0	2,233 ± 2,045	100	100
	D10	0	100	100
	Control
	D0	2,436 ± 1,239
	D10	2,297 ± 968

1 n – number of positive animals; EPG – eggs per gram; D0 – day of treatment; D10 – 10 days after treatment

Table 2.

Mean hatching (in %) with standard deviation (SD) and mean of ED₅₀ from the in vitro egg hatch test

TBZ concentration (μg/mL)	Mean hatching (%)	±SD
Control	96.25	0.43
0.05	96.00	1.22
0.1	91.25	4.22
0.3	84.00	1.73
0.5	71.50	4.55
1	54.50	3.22
Mean ED₅₀ ± SD	1.22	0.08

1 TBZ – thiabendazole; ED₅₀ – effective dose that inhibits egg hatching by 50%

Table 3.

Lethal dose (LD₅₀), minimum inhibitory concentration (MIC) and mean larval development ±SD at MIC thresholds for the three classes of anthelmintics obtained from the in vitro larval development tests

Drug	Larval development test
Drug	LD₅₀	MIC	L3 larvae (%) ± SD at MIC
Thiabendazole	0.37	n.a.	56.31 ± 5.19
Ivermectin	28.87	173.6	45.73 ± 6.32
Levamisole	0.10	1.0	0 ± 0

1 LD₅₀ – lethal dose that kills 50% of the larvae; MIC – minimum inhibitory concentration; L3 – third stage larvae; n.a. – not applicable (no inhibition of development to L3 stage at the highest concentration of thiabendazole)

Table 4.

Results of the morphological identification of third-stage larvae before and after treatment with albendazole (ALB), ivermectin (IVM) and levamisole (LEV)

Species	Before treatment (%)	After treatment (%)
Species	Before treatment (%)	ALB	IVM	LEV
Haemonchus contortus	77	100	100	—
Trichostrongylus spp.	13	—	—	—
Teladorsagia spp.	7	—	—	—
Oesophagostomum/Chabertia spp.	3	—	—	—

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DOI: https://doi.org/10.2478/jvetres-2023-0057 | Journal eISSN: 2450-8608 (formerly 2300-3235)

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Language: English

Page range: 575 - 581

Submitted on: May 22, 2023

Accepted on: Oct 9, 2023

Published on: Dec 19, 2023

Published by: National Veterinary Research Institute in Pulawy

In partnership with: Paradigm Publishing Services

Keywords:

sheep,

drug resistance,

alternative treatment,

Haemonchus contortus,

levamisole

Related subjects:

Life sciences,

Molecular biology,

Microbiology and virology,

Life sciences, other,

Medicine,

Veterinary medicine

© 2023 Michal Babják, Alžbeta Königová, Michaela Komáromyová, Tetiana Kuzmina, Pawel Nosal, Marián Várady, published by National Veterinary Research Institute in Pulawy
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Volume 67 (2023): Issue 4 (December 2023)