| 1. |
- Martis, Mihaela-Maria, et al.
(författare)
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RNA-Seqde novo assembly and differential transcriptome analysis of the nematode Ascaridia galli in relation to in vivo exposure to flubendazole
- 2017
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 12:11
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Tidskriftsartikel (refereegranskat)abstract
- The nematode Ascaridia galli (order Ascaridida) is an economically important intestinal parasite responsible for increased food consumption, reduced performance and elevated mortality in commercial poultry production. This roundworm is an emerging problem in several European countries on farms with laying hens, as a consequence of the recent European Union (EU) ban on conventional battery cages. As infection is associated with slow development of low levels of acquired protective immunity, parasite control relies on repeated use of dewormers (anthelmintics). Benzimidazoles (BZ) are currently the only anthelmintic registered in the EU for use in controlling A. galli and there is an obvious risk of overuse of one drug class, selecting for resistance. Thus we developed a reference transcriptome of A. galli to investigate the response in gene expression before and after exposure to the BZ drug flubendazole (FLBZ). Transcriptional variations between treated and untreated A. galli showed that transcripts annotated as mitochondrial glutamate dehydrogenase and cytochrome P450 were significantly down-regulated in treated worms, whereas transcripts homologous to heat shock proteins (HSP), catalase, phosphofructokinase, and a multidrug resistance Pglycoprotein (PGP1) were significantly up-regulated in treated worms. Investigation of candidate transcripts responsible for anthelmintic resistance in livestock nematodes led to identification of several tubulins, including six new isoforms of beta-tubulin, and several ligandgated ionotropic receptors and ABC-transporters. We discovered several transcripts associated with drug binding and processing genes, but further characterisation using a larger set of worms exposed to BZs in functional assays is required to determine how these are involved in drug binding and metabolism.
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| 2. |
- Tarbiat, Behdad, et al.
(författare)
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Comparison between anthelmintic treatment strategies against Ascaridia galli in commercial laying hens
- 2016
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Ingår i: Veterinary Parasitology. - : Elsevier BV. - 0304-4017 .- 1873-2550. ; 226, s. 109-115
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Tidskriftsartikel (refereegranskat)abstract
- The efficacy of a sustainable deworming strategy based on targeted treatments (TT) against Ascaridia galli was investigated for the first time in laying hen flocks on a Swedish commercial farm. Three experimental protocols with different levels of treatment, e.g. targeted treatment (TT), conventional treatment (CT) and untreated (UT), were tested in randomly allocated flocks of two different bird hybrids. Every second week faecal egg counts (FECs) were determined from pooled faecal materials collected on trays (20 x 27 cm) placed for a maximum of 12 h on the litter belts. In the TT, anthelmintic administration (fenbendazole, 1 mg/kg body weight for 5 days) started at 22 weeks post placement (wpp) and was repeated twice when the pooled FECs surpassed the assigned threshold of 200 egg per gram faeces (EPG). The CT flocks were treated once at 27 wpp using the same anthelmintic. Hens in the UT were not dewormed and served as controls. Additionally, FECs on cloacal contents, worm fecundity and worm burdens were determined at 19, 35 and 45 wpp. None of the flocks became infected until after 16 wpp. The cumulative pooled FECs at the end of the study were significantly (p < 0.01) lower in the TT compared to both CT and UT. Although repeated treatment in the TT protocol did not affect the fecundity, a worm density-dependent increase in fecundity was observed. Cloacal FECs and the number of adult A. galli in TT at 35 and 45 wpp were significantly lower compared to other flocks. This study provides evidence that the TT strategy is better in terms of lower worm burden and decreased cumulative environmental parasite egg numbers compared to CT strategy. The TT strategy should be considered as an alternative to the CT strategy with regard to A. galli control in commercial laying hens. (C) 2016 Elsevier B.V. All rights reserved.
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| 3. |
- Tarbiat, Behdad, et al.
(författare)
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Developmental capacity of Ascaridia galli eggs is preserved after anaerobic storage in faeces
- 2018
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Ingår i: Veterinary Parasitology. - : Elsevier BV. - 0304-4017 .- 1873-2550. ; 255, s. 38-42
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Tidskriftsartikel (refereegranskat)abstract
- The reliability of the results of in vitro studies such as detection of anthelmintic resistance often depends on the ability of the parasite eggs to develop under laboratory conditions. The aim of this study was to assess the embryonation capability of the chicken roundworm Ascaridia galli eggs after storage under different conditions. Two storage media for parasite eggs were used; faeces or water. Eggs in petri dishes (90 dishes in total) containing faces or water media were first exposed either to aerobic or anaerobic conditions at different temperatures (4 degrees C / + O-2, 4 degrees C / -O-2, 25 degrees C / -O-2) for a maximum of 72 days. Every second week, materials from petri dishes in triplicates were recovered and incubated aerobically for two weeks at 25 degrees C. After the incubation, 200-300 eggs from each petri shish (sampling unit) were counted and the number of embryonated eggs was determined. Data was analyzed in R (version 3.4.3) A logistic regression model with the probability of an egg to embryonate as dependent variable and conditions, storage medium and time points as fixed effects with quasibinomial distribution was run. Least-square means were calculated and pairwise comparisons were made with the fixed effect factors (condition, storage medium and time point). Eggs in faeces had a significantly (p < 0.05) higher embryonation than those in water, irrespective of storage conditions. At 4 degrees C embryonation tended to decline over time under aerobic conditions irrespective of the storage medium, whereas it remained constant following storage at anaerobic conditions. In contrast, anaerobic storage at the 25 degrees C negatively affected egg development in both media, except for day 14 in faeces. Our major finding was that eggs in faeces under anaerobic conditions and at 4 degrees C retained the highest rate of development, with a minimum decline in their developmental capacity over time compared to cleaned eggs stored in water.
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| 4. |
- Tarbiat, Behdad, et al.
(författare)
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Evaluation of benzimidazole resistance status in Ascaridia galli
- 2017
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Ingår i: Parasitology. - 0031-1820 .- 1469-8161. ; 144, s. 1338-1345
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Tidskriftsartikel (refereegranskat)abstract
- Susceptability of Ascaridia galli to benzimidazole (BZ) was investigated using faecal egg count reduction test (FECRT), in ovo larval development test (LDT) and genetic markers (mutations at codons 167, 198 and 200 of beta-tubulin gene). Six flocks (F1-F6) of a commercial laying hen farm with different number of exposure to BZ were recruited. The FECR was calculated by analyzing individual faeces (F1, F2, F4 and F5) before and 10 days after treatment. The LDT was performed on parasite eggs from pooled samples from F1 to F6 and LC50 and LC99 were calculated. DNA was extracted from 120 worms and sequenced for beta-tubulin gene. In all flocks, the FECRs were above 95% (lower CI above 90%). No significant difference was observed (p > 0.05) among obtained LC50 (F1/F4 and F2/F5 vs F3/F6) in the LDT. However, LC50 and LC99 were higher than suggested values for declaration of resistance in other nematode species. No variation was observed in codon positions involved in BZ resistance. Overall, our results indicated lack of evidence of resistance to BZ in A. galli. More research is needed to confirm these results and to further optimize the existing tools for detection and monitoring of anthelmintic resistance in A. galli.
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| 5. |
- Tarbiat, Behdad, et al.
(författare)
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The efficacy of flubendazole against different developmental stages of the poultry roundworm Ascaridia galli in laying hens
- 2016
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Ingår i: Veterinary Parasitology. - : Elsevier BV. - 0304-4017 .- 1873-2550. ; 218, s. 66-72
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Tidskriftsartikel (refereegranskat)abstract
- Infection with the poultry roundworm Ascaridia galli has increased in European countries due to the ban on battery cages. This study was conducted in two commercial laying hen flocks (F1 & F2) on different farms in central Sweden. The aims were to (1) investigate the efficacy of flubendazole (FLBZ, 1.43 mg/kg administered in drinking water for 7 days) against adult and larval stages including histotrophic larvae of A. galli, and (2) determine how long it took before the flocks were reinfected after deworming. Accordingly, 180 randomly selected hens were sacrificed before drug administration (bd), on day 3 and 7 during drug administration (dd), and on a weekly basis for up to five weeks post drug administration (pd). Intestinal contents and cloacal materials of each hen plus pooled faecal samples from manure belts were investigated to assess the worm burden and the parasite egg per gram faeces (epg). Additionally, drinking water, and serum and gastrointestinal digesta content samples obtained from ten treated animals were analyzed by HPLC to measure FLBZ and its reduced (R-FLBZ) and hydrolyzed (H-FLBZ) metabolites. No parasite eggs were observed in cloacal samples on day 21 and 28 pd on F1 and on day 21 pd on F2. The epg in manure decreased by 65% and 88% on day 3 dd and by 99% and 97% on day 35 pd on F1 and F2 respectively. Mean FLBZ concentrations quantified in duodenal contents ranged between 0.50 and 0.79 mu g/g. Although, no histotrophic larvae were found dd, they reappeared one week pd (7 +/- 7 F1, 0.5 +/- 0.5 F2). Adult worms were found in both flocks before drug administration (44 +/- 20 F1, 35 +/- 25 F2), on day 3 dd (4 +/- 3 F1, 2 +/- 2 F2), and then not until day 35 (0.2 +/- 0.6) on Fl and day 28 (0.4 +/- 0.9) pd on F2. Thus, the only period in which no A. galli were found was on day 7 dd. Although FLBZ was highly efficient our results indicate that the birds were reinfected already within one week pd. (C) 2016 Elsevier B.V. All rights reserved.
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