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Open access

M. Urda Dolinská, A. Königová, M. Babják and M. Várady

Summary

Gastrointestinal parasitic nematodes in sheep cause severe economic losses. Anthelmintics are the most commonly used drugs for prophylaxis and therapy against parasitic helminths. The problem of drug resistance has developed for all commercially available anthelmintics in several genera and classes of helminths. In vitro and in vivo tests are used to detect anthelmintic resistance. Two in vitro methods (larval migration inhibition test and micromotility test) for the detection of ivermectin (IVM) resistance were compared using IVM-resistant and IVM-susceptible isolates of Haemonchus contortus. The degree of resistance for each test was expressed as a resistance factor (RF). The micromotility test was more sensitive for quantitatively measuring the degree of resistance between susceptible and resistant isolates. The RFs for this test for IVM and eprinomectin ranged from 1.00 to 108.05 and from 3.87 to 32.32, respectively.

Open access

M. Babják, A. Königová, M. Urda-Dolinská and M. Várady

Summary

The aim of this study was to identify the most common gastrointestinal (GI) parasites in flocks of dairy goats on 30 farms in Slovakia. A total of 944 adult goats were examined during the pasturing seasons for 2014 – 2016. Eggs from one or more species of gastrointestinal parasites were identified in 906 of the samples (95.90 %). Strongyle eggs were present in most of the samples (92.00 %), followed by Strongyloides papillosus (14.05 %), Trichuris spp. (7.84 %), Nematodirus spp. (3.98 %), and Moniezia spp. (2.65 %). The counts of strongyle eggs per gram of faeces ranged from 0 to 11 000. Subsamples from each farm were used to prepare faecal coprocultures to identify the genera of the nematodes. Third-stage larvae of Trichostrongylus spp. (100 %) and Teladorsagia/Ostertagia spp. (96.60 %) were present on most of the farms, followed by Oesophagostomum spp./Chabertia ovina (86.60 %) and Haemonchus contortus (76.60 %). Teladorsagia/Ostertagia spp. were the dominant genera on 60 % of the farms.

Open access

A. Königová, G. Hrčková, S. Velebný, M. Dolinská, L. Molnár and M. Várady

Abstract

The effect of albendazole therapy on the reduction of drugsusceptible and drug-resistant strains of Haemonchus contortus larvae on day 10 post infection (p.i.), distribution and the relative numbers of innate immunity cells — eosinophils/neutrophils and mast cells in the stomach wall of immunosupressed Mongolian gerbils on days 4/1, 7/4, 10/7 and 14/11 post infection/post therapy (p.i./p.t.) were investigated in the present study. The efficacy of albendazole was significantly lower on benzimidazole (BZ) resistant larvae (L3 and L4 stages) (58.92 %) than the efficacy on susceptible strain of larvae (94.15 %). H. contortus infection elicited strong inflammation in mucosal and submucosal layers of the stomach, where mucosal mast cells MMC) were in the highest numbers in the lamina propria mucosae on day 7/4 p.i./p.t. Reduction of larval numbers following treatment resulted in a gradual decrease of MMC and connective tissue mast cells (CTMC). The lower counts of CTMC in the submucosa were seen in gerbils infected with BZ-susceptible strain during the whole period post therapy. In case of infection with BZ-resistant strain, peroxidase containig cells (eosinophils) peaked on day 7/4 p.i./p.t., whereas infection with BZ-susceptible strain elicited massive accumulation of these cells on day 4/1 p.i./p.t., particularly in the submucosa. No marked differences in eosinophils localisation were observed between both groups after the therapy. Goblet cells were found only in the proximal parts of glandulae gastricae close to the mucosal surface and no differences in the distribution in the stomach wall of both groups of animals were observed. After therapy the higher larval counts in case of BZ-resistant strain were in the correlation with the lower decline of CTMC and eosinophils, but MMC numbers were not significantly different between both treated groups. Present data indicate that in early stage post infection, the distribution of individual innate immunity cells might be directly affected by the larvae, and that the genetic and consequently biological differences related to the resistance to benzimidazoles probably had the impact on the interactions of larvae with the different immune cells in their niche.

Open access

V. Šnábel, A. Königová, M. Dolinská, A. Wolstenholme and M. Várady

Abstract

In an attempt to investigate the genetic and biochemical causes underlying resistance to anthelmintics, the trichostrongylid nematode Haemonchus contortus was examined by an allozymic analysis of nine candidate geneenzyme systems. Two strains resistant to benzimidazoles, two multidrug-resistant strains, and three strains susceptible to anthelmintics isolated from three continents were examined by isoelectric focusing. Two enzymes (mannose phosphate isomerase and peptidase-D) had polymorphic patterns. The peptidase-D zymograms indicated an association with the selection for resistance. Susceptible isolates gave more complex patterns due to the formation of a heterodimer controlled by the two active loci, whereas in resistant isolates, only a single locus with one electromorph was responsible for the profiles. A possible link between dipeptidases and the acquisition of resistance through the turnover of proteinrich collagen, and changes in membrane-associated genes that influence drug efflux, are discussed.

Open access

M. Várady, E. Papadopoulos, M. Dolinská and A. Königová

Abstract

Anthelmintic 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 ED50 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.

Open access

Iwona Dolińska, Mariusz Jakubowski, Antoni Masiukiewicz, Grzegorz Rządkowski and Kamil Piórczyński

Abstract

Channel assignment in 2.4 GHz band of 802.11 standard is still important issue as a lot of 2.4 GHz devices are in use. This band offers only three non-overlapping channels, so in crowded environment users can suffer from high interference level. In this paper, a greedy algorithm inspired by the Prim’s algorithm for finding minimum spanning trees (MSTs) in undirected graphs is considered for channel assignment in this type of networks. The proposed solution tested for example network distributions achieves results close to the exhaustive approach and is, in many cases, several orders of magnitude faster.