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Falcón-Ordaz J, García-Prieto L. A new species of Vexillata (Nematoda: Trichostrongylina: Ornithostrongylidae) parasite of Heteromys desmarestianus (Rodentia: Heteromyidae) from Costa Rica. J Parasitol 2005; 91:329-34. [PMID: 15986608 DOI: 10.1645/ge-414r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
In July 1999, 2 heteromyid rodents Heteromys desmarestianus Gray, 1868, were collected from the Area de Conservación Guanacaste, Costa Rica, and examined for parasites. Individuals of a new species of Vexillata (Travassos, 1937) Durette-Desset, 1970, were found from the intestine of hosts. Vexillata brooksi n. sp. differs from all other congeners by the presence of spicules divided at the tip instead of simple spicules. The new species closely resembles Vexillata legallae Denke, 1977, and Vexillata convoluta (Caballero and Cerecero, 1943); however, it can be distinguished from both species by possessing a smaller number of cuticular ridges at the posterior part of the body in males (9 vs. 11 and 12, respectively) and by the absence of a carene at this level.
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Hoberg EP, Abrams A. Pseudostertagia bullosa (Nematoda: Trichostrongyloidea) in artiodactyl hosts from North America: redescription and comments on systematics. J Parasitol 2005; 91:370-81. [PMID: 15986613 DOI: 10.1645/ge-3419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A relationship for Pseudostertagia bullosa within the trichostrongyloids has been enigmatic or unresolved. Studies of the synlophe in males and females of P. bullosa revealed a tapering system anterior to the deirids and a pattern of parallel ridges extending to near the caudal extremity in both lateral and median fields. Structurally, the synlophe differs considerably from that seen among the Cooperiinae and exhibits homoplasy with respect to ridge systems among some Ostertagiinae. Other structural characters due to symplesiomorphy, homoplasy or because they represent autapomorphies do not serve to reveal the putative relationships for P. bullosa with other trichostrongyloids. Although somewhat equivocal, the 2-2-1 pattern of the bursa and position of rays 2 and 3 suggest an association with the Cooperinae, as postulated by Durette-Desset and others. Pseudostertagia bullosa appears to be a species that has survived in the pronghorn, Antilocapra americana, a relictual pecoran artiodactyl that occurs in xeric regions of western North America; pronghorn are the sole remnant of the late Tertiary radiation for Antilocapridae across North America. Pseudostertagia bullosa may occur in mixed infections with a number of ostertagiines in the abomasa of mule deer (Odocoileus hemionus) and domestic sheep (Ovis aries) in regions of sympatry for pronghorn and these artiodactyl hosts.
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Eysker M, Bakker N, Kooyman FNJ, Ploeger HW. The possibilities and limitations of evasive grazing as a control measure for parasitic gastroenteritis in small ruminants in temperate climates. Vet Parasitol 2005; 129:95-104. [PMID: 15817209 DOI: 10.1016/j.vetpar.2004.12.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Revised: 12/13/2004] [Accepted: 12/21/2004] [Indexed: 10/25/2022]
Abstract
Between 1999 and 2003 studies were done at Utrecht University on the population dynamics of gastrointestinal nematodes and the potential to use evasive grazing for the control of nematode infections in small ruminants. On most pastures grazed in May and June it took at least 3 weeks before high pasture infectivity levels for Haemonchus contortus developed while it took at least 2 weeks on pastures grazed in July, August and September. Occasionally, larvae emerged earlier on pasture when high temperatures coincided with rain. Pasture infectivity levels for H. contortus subsequently increased and the highest levels were found between 5 and 9 weeks on pastures grazed in May-June and between 3 and 9 weeks on pastures grazed in July, August and September. Pasture infectivity usually had decreased again to low levels after approximately 3 months. Larvae of the other trichostrongylids emerged later on pasture. However, patterns of Teladorsagia circumcincta, Trichostrongylus spp. and Cooperia curticei were basically similar to H. contortus. Strongyloides papillosus larvae emerge within 2 weeks on pasture and survival is short. On the other hand Nematodirus larvae took a lot longer to emerge on pasture than the other trichostrongylids. The results imply that only on a small proportion of farms (mixed dairy cattle/sheep farms; some organic dairy goat farms) evasive grazing can be recommended as only control measure for parasitic gastroenteritis. However, the present data offer possibilities to combine evasive grazing with other methods in an integrated control scheme.
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Min BR, Hart SP, Miller D, Tomita GM, Loetz E, Sahlu T. The effect of grazing forage containing condensed tannins on gastro-intestinal parasite infection and milk composition in Angora does. Vet Parasitol 2005; 130:105-13. [PMID: 15893077 DOI: 10.1016/j.vetpar.2005.03.011] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2005] [Indexed: 11/23/2022]
Abstract
The objective of this study was to evaluate effects of the condensed tannin (CT)-containing forage sericea lespedeza (sericea lespedeza (SL); Lespedeza cuneata; 15.2% CT), on fecal egg count (FEC), larval development (larvae/10 g of feces), worm burden and immune response compared with a crabgrass (Digitaria ischaemum)/Kentucky 31 tall fescue (Festuca arundinacea; control forage (CTF)) forage low in CT (0.32% CT) in grazing Angora does and their kids. Fifty worm-free mixed-age does were randomly allocated to three treatments. One treatment (10 does; initial liveweight (LW) = 45+/-1.5 kg) entailed grazing of SL forage from April 25 to July 15, 2002 with a second treatment of CTF (20 does; initial LW = 43+/-1.4 kg) grazing during the same period. Does of the third treatment (20 does; initial LW = 44+/-1.4 kg) grazed a sward of SL for 2 weeks and then one of CTF for 2 weeks followed by alternating between the two pastures every 2-week rotational grazing (ROT). To gauge levels of infective larvae on pasture, three worm-free Angora kids (initial LW = 3.6+/-0.2 kg) were randomly selected as tracers. Tracers grazed for final 60 days and were euthanized for determination of worm burden. The immune response of does was measured by skin thickness reaction after the intradermal injection of 250 microg phytohemagglutinin (PHA). Mean FEC for SL and ROT were substantially lower (P < 0.01) than for CTF does (145, 329 and 894 eggs/g, respectively). The FEC for kids was lower (P < 0.05) for SL than for ROT and CTF (550, 2757 and 3600 eggs/g, respectively). Total fecal egg output (3.3, 6.0 and 26.9 x 10(5) eggs/day, respectively) and larval development (242, 263 and 792 larvae/10 g, respectively) were lower (P < 0.05) for SL and ROT than for CTF. Tracers grazing on SL had lower total worm burdens than ROT and CTF (P < 0.01). The immune response was higher (P < 0.01) for SL (4.9 mm) and ROT (6.0 mm) than for CTF (3.0 mm) at 12 h after injection of PHA. The packed cell volume (PCV) in does was higher (P < 0.01) for SL and ROT than for CTF (27, 26 and 23%, respectively). Does that grazed CT-containing forage had considerably lower milk somatic cell counts (SCC) than does grazing non-CT-containing forage. In summary, grazing CT forages reduced FEC, larval development and worm burden, and also appeared to enhance immune response. The CT-containing forage SL reduced gastro-intestinal parasite infections of Angora does and kids.
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Muturi KN, Scaife JR, Lomax MA, Jackson F, Huntley J, Coop RL. The effect of dietary polyunsaturated fatty acids (PUFA) on infection with the nematodes Ostertagia ostertagi and Cooperia oncophora in calves. Vet Parasitol 2005; 129:273-83. [PMID: 15845283 DOI: 10.1016/j.vetpar.2005.01.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Revised: 12/24/2004] [Accepted: 01/21/2005] [Indexed: 10/25/2022]
Abstract
Diet-induced changes in the polyunsaturated fatty acid (PUFA) content of immune cells influences the immune phenotype that develops following infection. The aim of this study was to examine the effect of manipulating dietary PUFA supply on tissue fatty acids composition and immunity to a mixed infection with an abomasal and an intestinal nematode parasite in calves. Calves (n=24) were allocated into two treatment groups and fed 25 g/day of either fish oil (n-3 group) or a binary mixture of palm/rapeseed oil (normal group) as a supplement in milk replacer. Within each treatment group eight calves were infected with 2000 L3 Ostertagia ostertagi and Cooperia oncophora, three times per week for 8 weeks, the remaining calves were pair-fed uninfected controls. Faecal egg counts (FEC) were carried out twice weekly. At slaughter, the whole gut was removed intact for worm counts and tissue samples were taken for fatty acid analysis. Samples of abomasum, duodenum and mid-gut were also collected for immunohistological analysis. FEC were not significantly influenced by oil supplement but tended to remain higher in the palm/rapeseed oil-fed group (normal infected). The number of intestinal immature worms was significantly (p<0.05) higher in the n-3 group. Mucosal mast cell (MMC) and eosinophil numbers were significantly increased (p<0.05) by infection and were significantly lower (p<0.05) in the intestinal tissue of the fish oil supplemented and infected group (n-3 infected group). These results suggest that feeding an n-3 PUFA-rich supplement (fish oil) can influence cellular mediators of immunity to nematode infection. This is the first report of the establishment of patency and the subsequent development of immunity to a mixed infection with O. ostertagi and C. oncophora in calves undergoing early rumen development. The trend in the FEC, MMC and eosinophil numbers in the n-3 group suggests that decreasing the dietary n-6/n-3 PUFA ratio may be a worthwhile immunonutritional strategy for potentiating the immune response to nematode parasite infection in the calf.
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Alvarez-Sánchez MA, Pérez García J, Bartley D, Jackson F, Rojo-Vázquez FA. The larval feeding inhibition assay for the diagnosis of nematode anthelmintic resistance. Exp Parasitol 2005; 110:56-61. [PMID: 15804379 DOI: 10.1016/j.exppara.2005.02.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2004] [Revised: 01/26/2005] [Accepted: 02/01/2005] [Indexed: 11/24/2022]
Abstract
A larval feeding assay for detection of nematode anthelmintic resistance to macrocyclic lactones and imidazothiazoles is described. The estimated concentration of anthelmintic required to inhibit larval feeding in 50% of L1's (IC50) that were resistant to either macrocyclic lactones or imidazothiazoles were significantly higher (P < or = 0.05) than those of susceptible isolates. Some variations in IC50 values were observed during the patent period of infection in all strains, although the pattern of the IC50 followed the same course. IC50 values varied in larvae developing from eggs shed throughout the patent period, with low values in the earliest larvae followed by higher values as the infection progressed, before decreasing at 70-90 days post-infection, although the low values of the first part of the patent period were not reached. However, the IC50 differences between all resistant and susceptible strains were significant throughout the whole patent period for ivermectin and levamisole. These results suggest that this technique may provide an alternative in vitro to detect anthelmintic resistance.
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Alvarez-Sánchez MA, Pérez-García J, Cruz-Rojo MA, Rojo-Vázquez FA. Real time PCR for the diagnosis of benzimidazole resistance in trichostrongylids of sheep. Vet Parasitol 2005; 129:291-8. [PMID: 15845285 DOI: 10.1016/j.vetpar.2005.02.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 10/26/2004] [Accepted: 02/08/2005] [Indexed: 11/23/2022]
Abstract
This report describes a new molecular method for the diagnosis of benzimidazole susceptibility or resistance in three main species of trichostrongylids of sheep (Haemonchus contortus, Teladorsagia circumcincta and Trichostrongylus vitrinus). This assay is based on the use of real time polymerase chain reaction (PCR) to detect mutations of residue 200 on isotype 1 of beta-tubulin. The technique allows calculation of the proportion of each allelic variant as it combines kinetic (real time quantitative) PCR with allele-specific amplification and requires no post-PCR processing. The level of resistance in the population is determined by the proportion of the beta-tubulin codon 200 TAC allele. Hence, it was observed that the proportion of the resistant allele in susceptible strains ranged between 24% and 32.3%; in resistant strains this value increased to between 71.3% and 86.3%. Furthermore, there was a good correlation between real time PCR, faecal egg count reduction test, egg hatch assay and conventional allele-specific PCR, in both resistant and susceptible strains. A sensitive, rapid, highly reproducible and inexpensive technique for detecting resistance to benzimidazoles in a worm population has been developed.
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Gaba S, Ginot V, Cabaret J. Modelling macroparasite aggregation using a nematode-sheep system: the Weibull distribution as an alternative to the Negative Binomial distribution? Parasitology 2005; 131:393-401. [PMID: 16178361 DOI: 10.1017/s003118200500764x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Macroparasites are almost always aggregated across their host populations, hence the Negative Binomial Distribution (NBD) with its exponent parameter k is widely used for modelling, quantifying or analysing parasite distributions. However, many studies have pointed out some drawbacks in the use of the NBD, with respect to the sensitivity of k to the mean number of parasites per host or the under-representation of the heavily infected hosts in the estimate of k. In this study, we compare the fit of the NBD with 4 other widely used distributions on observed parasitic gastrointestinal nematode distributions in their sheep host populations (11 datasets). Distributions were fitted to observed data using maximum likelihood estimator and the best fits were selected using the Akaike's Information Criterion (AIC). A simulation study was also conducted in order to assess the possible bias in parameter estimations especially in the case of small sample sizes. We found that the NBD is seldom the best fit for gastrointestinal nematode distributions. The Weibull distribution was clearly more appropriate over a very wide range of degrees of aggregation, mainly because it was more flexible in fitting the heavily infected hosts. Moreover, the Weibull distribution estimates are less sensitive to sample size. Thus, when possible, we suggest to carefully check on observed data if the NBD is appropriate before conducting any further analysis on parasite distributions.
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Tinar R, Akyol CV, Cirak VY, Senlik B, Bauer C. Investigations on the seasonal patterns of strongyle infections in grazing lambs, and the occurrence of anthelmintic resistance on sheep and goat farms in western Anatolia, Turkey. Parasitol Res 2005; 96:18-23. [PMID: 15765247 DOI: 10.1007/s00436-005-1312-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2005] [Accepted: 01/11/2005] [Indexed: 11/25/2022]
Abstract
The seasonal patterns of strongyle infections in untreated, weaned lambs were determined on four governmental farms during a grazing season. In three farms, the infection level (predominantly Teladorsagia spp. and Trichostrongylus spp.) measured by egg counts or worm burdens remained low throughout the study; higher egg counts mainly caused by Haemonchus contortus were transiently recorded on the fourth farm. Significant body weight gains were observed in all groups, but they varied between farms irrespective of the level of strongyle infections, suggesting that the economic effectiveness of anthelmintic treatments of weaned lambs is doubtful under the extensive grazing conditions and the hot, dry climate in the region. In the second part of the study, faecal egg count reduction tests were performed for albendazole, thiabendazole, tetramisole and ivermectin on 12 sheep and goat farms to provide first information on anthelmintic resistance in trichostrongyles of small ruminants in Turkey. There was no hint of benzimidazole resistance, and unequivocal evidence of ivermectin resistance was missing. In contrast, tetramisole resistance was detected on one sheep farm.
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Sargison ND, Jackson F, Bartley DJ, Moir ACP. Failure of moxidectin to control benzimidazole–, levamisole– and ivermectinresistant
Teladorsagia circumcincta
in a sheep flock. Vet Rec 2005; 156:105-9. [PMID: 15704550 DOI: 10.1136/vr.156.4.105] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Control of a benzimidazole-, levamisole- and ivermectin-resistant population of Teladorsagia circumcincta was attempted using moxidectin administered orally at the manufacturer's recommended dose rate of 200 microg/kg bodyweight. Ewes were dosed after lambing with the aim of controlling their periparturient rise in faecal egg output and lambs were dosed at six-week intervals throughout the summer. This regimen failed to suppress the establishment of significant numbers of infective helminth larvae on the pasture, resulting in unsatisfactory lamb production. Oral dosing with moxidectin was effective in removing adult female burdens of ivermectin-resistant T. circumcincta, but the effect of the drug did not persist against the resistant helminth population.
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Chartier C, Pors I. Duration of activity of topical eprinomectin against experimental infections with Teladorsagia circumcincta and Trichostrongylus colubriformis in goats. Vet Parasitol 2004; 125:415-9. [PMID: 15482897 DOI: 10.1016/j.vetpar.2004.07.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Revised: 07/13/2004] [Accepted: 07/25/2004] [Indexed: 11/16/2022]
Abstract
The immediate as well as the persistent anthelmintic efficacies of topically applied eprinomectin were evaluated in goats against induced infections with Teladorsagia circumcincta (2800 L3) and Trichostrongylus colubriformis (6000 L3). Twenty-three culled dairy goats were allocated to the following groups: control animals (group 1), animals treated 21 days prior to nematode infection (group 2), animals treated 7 days prior to nematode infection (group 3) and animals treated 21 days after nematode infection (group 4). Eprinomectin was applied at twice the cattle dose rate (1.0 mg/kg BW). According to the groups, necropsies were undertaken 28 days after nematode infection (groups 1-3) or 14 days after the anthelmintic treatment (group 4). Worm counts were determined for abomasum and small intestine. The curative anthelmintic efficacy of eprinomectin at 1.0 mg/kg BW on existing worm burdens was 100% against T. circumcincta and T. colubriformis. Quite similar worm burdens reductions were observed when eprinomectin was administered 7 days before infection whereas they were only 52.4 and 17.8% for T. circumcincta and T. colubriformis, respectively, for an administration of the drug 21 days prior to the nematode infection.
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Gruner L, Cortet J, Sauvé C, Hoste H. Regulation of Teladorsagia circumcincta and Trichostrongylus colubriformis worm populations by grazing sheep with differing resistance status. Vet Res 2004; 35:91-101. [PMID: 15099506 DOI: 10.1051/vetres:2003043] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In an experiment lasting 4 years, changes in the Teladorsagia circumcincta and Trichostrongylus colubriformis populations were compared in lambs and adult sheep with differing resistance statuses. Two flocks of 30 rams (resistant R and susceptible S) grazed separate pastures and 8 rams were slaughtered in the middle and at the end of each grazing season. Five groups of tracer lambs were added each year to estimate the pasture infectivity and were killed for worm counts. The availability of animals with differing resistance statuses (rams and tracer lambs) and differing levels of infection made it possible to investigate the number, size and fecundity of worms of these two species. The inflammatory response was measured in the rams by counting the globule leukocytes, mast cells and eosinophils in the fundic, pyloric and intestinal mucosa. In the tracer lambs, the daily egg production by the female worms of both species was negatively correlated with the worm burden. Worm length accounted for 60 and 70% of the variation in the number of eggs in utero for T. circumcincta and T. colubriformis respectively. Worm length was closely associated with the resistance status of the host; there were greater differences between lambs, and S and R rams for T. colubriformis. T. circumcincta worm lengths were not affected by the worm number. Globule leukocyte counts were related to the worm burdens, and mast cell counts to worm length in the R and S rams. The number, size and fecundity of the worms may well be regulated by similar mechanisms in both species, but T. colubriformis seemed to be more intensively regulated than T. circumcincta. This finding could be useful in devising more effective methods of parasite control.
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Jackson F, Greer AW, Huntley J, McAnulty RW, Bartley DJ, Stanley A, Stenhouse L, Stankiewicz M, Sykes AR. Studies using Teladorsagia circumcincta in an in vitro direct challenge method using abomasal tissue explants. Vet Parasitol 2004; 124:73-89. [PMID: 15350663 DOI: 10.1016/j.vetpar.2004.06.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2003] [Revised: 05/05/2004] [Accepted: 06/16/2004] [Indexed: 11/20/2022]
Abstract
An in vitro direct challenge (IVDC) method in which abomasal tissue explants maintained at 37 degrees C in Hanks/Hepes solution (pH 7.6) in a high oxygen concentration (incubator gassed with pure oxygen and sealed prior to use) were-challenged with exsheathed third stage larvae of Teladorsagia circumcincta has been used to investigate the tissue association phase of larval establishment. Studies using naïve and recently challenged immune sheep and goat abomasal tissues have shown significant reductions (P < 0.05) in the numbers of tissue associated larvae in material from immune animals. The mechanisms that affect the tissue association process appear to be labile since more larvae were recovered from the tissue digests of previously infected sheep that had not been recently exposed to larval challenge in comparison to those that had been recently challenged (P < 0.05). The method has also been used to demonstrate the influence of protein nutrition on the establishment of larvae in abomasal tissues and region specific differences in the efficacy of exclusion mechanisms. The technique appears to have potential as a means of investigating the crucial first phase of the process of establishment.
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Bartley DJ, Jackson F, Jackson E, Sargison N. Characterisation of two triple resistant field isolates of Teladorsagia from Scottish lowland sheep farms. Vet Parasitol 2004; 123:189-99. [PMID: 15325045 DOI: 10.1016/j.vetpar.2004.06.018] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Revised: 05/28/2004] [Accepted: 06/04/2004] [Indexed: 11/21/2022]
Abstract
The anthelmintic resistance status of two field isolates derived from farms (farm A and B) located near Edinburgh were examined using both controlled efficacy tests (CET) and faecal egg count reduction tests (FECRT). Efficacies against fenbendazole (FBZ), levamisole (LEV) and ivermectin (IVM) and, for one isolate, against combinations of these anthelmintics and moxidectin were determined in naïve lambs, artificially infected with the isolates and treated with the compounds at the manufacturers recommended dose rates. (FBZ, 5mg/kg bodyweight (BW); LEV, 7.5mg/kg BW; IVM, 0.2mg/kg BW; Moxidectin (MOX) 0.2mg/kg BW). In both field isolates, the predominant species found pre-treatment and the only species found post-treatment was Teladorsagia circumcincta. Resistance to FBZ, LEV and IVM was confirmed in CET and FECRT on farm A and to the latter two compounds on farm B, which had a history of benzimidazole resistance and where TBZ resistance was also demonstrated using an egg hatch assay (EHA). For the farm A isolate CET efficacies against FBZ; IVM; LEV; FBZ + IVM; FBZ + LEV; FBZ, LEV + IVM and MOX were 59, 60, 88, 94,93, 92 and 98%, respectively. The CET efficacies for the farm B isolate were 51% and 72% for LEV and IVM, respectively.
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Braisher TL, Gemmell NJ, Grenfell BT, Amos W. Host isolation and patterns of genetic variability in three populations of Teladorsagia from sheep. Int J Parasitol 2004; 34:1197-204. [PMID: 15380691 DOI: 10.1016/j.ijpara.2004.06.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Revised: 06/18/2004] [Accepted: 06/24/2004] [Indexed: 11/19/2022]
Abstract
We have used a mitochondrial marker to explore the population genetics of an economically important parasite of sheep, Teladorsagia. We examined diversity within and between parasites from three very different host populations, as well as within and between individual hosts. One of our study populations, the Soay sheep on Hirta, St Kilda, is unusually isolated with no sheep having been introduced to the island since 1932. Worm haplotypes from Hirta were compared with those from two other host populations. Remarkably, despite its historical isolation the Hirta population shows similar levels of within-population diversity to the other study populations. No divergence between the three Teladorsagia populations was found, consistent with gene flow between the populations. The high diversity within Teladorsagia populations provides compelling evidence that this variability is a general feature of parasitic nematode populations. Such diversity may be caused by high effective population size, coupled with an increased mutation rate for mtDNA, which has important implications for the spread of anthelmintic resistance in nematode populations.
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Stear MJ, Bairden K, Innocent GT, Mitchell S, Strain S, Bishop SC. The relationship between IgA activity against 4th-stage larvae and density-dependent effects on the number of 4th-stage larvae ofTeladorsagia circumcinctain naturally infected sheep. Parasitology 2004; 129:363-9. [PMID: 15471011 DOI: 10.1017/s0031182004005736] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The number ofTeladorsagia circumcincta4th-stage larvae in naturally infected lambs from a single farm varied among lambs and among different years. Within each year the distribution of 4th-stage larvae among lambs was similar to that expected from a negative binomial distribution. The ratio of 4th-stage larvae to adultT. circumcinctawas low in two years with a low mean intensity of infection but high in two years with a higher mean intensity of infection. The negative binomial distribution is defined by the mean and byk, a parameter that measures dispersion;kwas low when mean infection intensity was low but higher when mean infection intensity was high. Askis an inverse index of overdispersion this indicated that the distribution of 4th-stage larvae was more overdispersed at low levels of infection. In a combined analysis, the number of adultT. circumcinctaand the plasma IgA activity against 4th-stage larvae were both associated with increased numbers of 4th-stage larvae. There was a statistical interaction between the number of adults and IgA activity that moderated their combined effect.
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67
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Njue AI, Prichard RK. Efficacy of ivermectin in calves against a resistant Cooperia oncophora field isolate. Parasitol Res 2004; 93:419-22. [PMID: 15293046 DOI: 10.1007/s00436-004-1149-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2004] [Accepted: 05/28/2004] [Indexed: 11/28/2022]
Abstract
Since 1999, two Cooperia oncophora isolates, originally obtained from the United Kingdom, have been maintained by regular passage through calves at the Macdonald Campus, McGill University farm. One isolate, IVS, was originally susceptible to ivermectin, while the IVR isolate was originally resistant to ivermectin. These two isolates have been used to study the mechanisms of ivermectin resistance. To confirm the susceptible/resistant status after 4 years of passaging through calves, a controlled study was performed in which two worm-free calves were experimentally infected with IVS and another two worm-free calves with the IVR infective larvae. The calves were treated with ivermectin (0.2 mg/kg) subcutaneously (Ivomec Injection) 21 days after infection. Ivermectin at the recommended dose was 100% effective at eliminating the IVS isolate, since no eggs were found in feces, and no adult worms were found in the small intestine of the treated IVS-infected calf. In contrast, the IVR-infected calf continued to pass eggs in feces even after treatment with ivermectin, and adult worms (250) were found in the small intestine at necropsy. The untreated calves had 1,330 and 848 adult worms, respectively, for the IVS and IVR infected animals.
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Paolini V, Fouraste I, Hoste H. In vitroeffects of three woody plant and sainfoin extracts on 3rd-stage larvae and adult worms of three gastrointestinal nematodes. Parasitology 2004; 129:69-77. [PMID: 15267113 DOI: 10.1017/s0031182004005268] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Most studies on the effects of tanniferous plants on nematodes have examined forages but have neglected the woody plants. Therefore,in vitroeffects of extracts from 3 woody plants (Rubus fructicosus,Quercus robur,Corylus avellana) have been tested on trichostrongyles and compared to sainfoin, a legume forage. Because somein vivoresults indicated that the effects of tannins differed depending on the parasitic species and/or stages, the effects were measured on 3rd-stage larvae (L3) and adult worms ofTeladorsagia circumcincta,Haemonchus contortusandTrichostrongylus colubriformis. The effects of plant extracts varied according to the plant sources, the parasite species and stages. For the woody plants, significant inhibitory effects were obtained on both stages of abomasal species. Results forT. colubriformiswere more variable. Effects of sainfoin extracts were significant onT. colubriformisandH. contortusL3, and on abomasal adult worms. In order to assess the implications of tannins, polyethylene glycol (PEG), an inhibitor of tannins, was added to hazel tree, oak and sainfoin extracts. Without PEG, significant inhibitory effects on L3 and adult worms were confirmed. After addition of PEG, the larval migration and motility of adult worms were restored in most cases. These results confirm variations in effects depending on factors related to plants or parasites and suggest that tannins are partly responsible for the effects.
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69
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Garijo MM, Ortiz JM, Ruiz de Ibáñez MR. Helminths in a giraffe (Giraffa camelopardalis xgiraffa) from a zoo in Spain. Onderstepoort J Vet Res 2004; 71:153-6. [PMID: 15373337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023] Open
Abstract
A pregnant female Cape giraffe (Giraffa camelopardalis giraffa) died from an unknown cause in the Aitana Zoo, Alicante, Spain. Neither clinical signs nor macroscopic lesions were observed at necropsy. The alimentary tract was removed and examined for parasites. A total of 2 724 nematodes were found, including Camelostrongylus mentulatus, Trichostrongylus axei, Ostertagia ostertagi, Teladorsagia circumcincta, Teladorsagia trifurcata, Marshallagia marshalli, Trichostrongylus vitrinus, Trichostrongylus colubriformis, Spiculopteragia asymmetrica and Trichuris giraffae. Only T. giraffae and C. mentulatus have been previously reported from giraffes. The other nematodes are common in mouflons, fallow and red deer, which can usually be found in the same paddock as the giraffes in Aitana Zoo. Although its occurrence is unusual in this host, C. mentulatus was the most abundant nematode in our giraffe. This parasite has been related to disease, and even death, in several wild ruminants.
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70
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Papadopoulos E, Sotiraki S, Himonas C, Fthenakis GC. Treatment of small lungworm infestation in sheep by using moxidectin. Vet Parasitol 2004; 121:329-36. [PMID: 15135874 DOI: 10.1016/j.vetpar.2004.02.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2003] [Revised: 01/29/2004] [Accepted: 02/23/2004] [Indexed: 11/19/2022]
Abstract
The use of moxidectin (MXD) in the treatment of small lungworm infestation (Cystocaulus ocreatus, Muellerius capillaris, Neostrongylus linearis and Protostronglylus rufescens) in sheep, was evaluated. Twenty-one sheep naturally infested with small lungworms, were divided into three groups (n = 7) and treated as follows: group A with moxidectin 1% injectable solution at a dose rate of 0.2mgkg(-1) bodyweight, group B with moxidectin 0.1% oral drench at a dose rate of 0.2 mgkg(-1) bodyweight and group C being controls. Before treatment, mean faecal larval counts were 30.7, 21.1 and 26.7 lpg in group A, B and C, respectively; 14 days after treatment respective counts were 0.4, 2.3 and 63.0 lpg, (percentage reduction after moxidectin administration >96.0%); 60 days after treatment respective counts were 0.0, 0.0 and 26.4 lpg, (percentage reduction after moxidectin administration 100%). It is concluded that treatment of small lungworm infestation of sheep can be effected by using moxidectin.
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71
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Winterrowd CA, Pomroy WE, Sangster NC, Johnson SS, Geary TG. Benzimidazole-resistant beta-tubulin alleles in a population of parasitic nematodes (Cooperia oncophora) of cattle. Vet Parasitol 2004; 117:161-72. [PMID: 14630425 DOI: 10.1016/j.vetpar.2003.09.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Three anthelmintic classes with distinct mechanisms of action are commercially available. Selection of nematode populations resistant to all these drugs has occurred, particularly in trichostrongyloid parasites of sheep. Anthelmintic resistance in cattle parasites has only recently been recognized and appears to be less pronounced, even though very similar species infect both hosts. To understand the bases for differences in the rate of resistance development in sheep versus cattle parasites, it is important to first demonstrate that the same kinds of resistance alleles exist in both. The benzimidazoles (BZ), which have been used for more than 40 years, were chosen as an example. BZ-sensitive (BZ(S)) and BZ-resistant (BZ(R)) nematodes that parasitize sheep have been distinguished at the molecular level by a single nucleotide change in the codon for amino acid 200 of a beta-tubulin gene, a switch from TTC (phenylalanine) to TAC (tyrosine). PCR primers were designed to completely conserved regions of trichostrongyloid beta-tubulin genes and were used to amplify DNA fragments from Haemonchus contortus (cDNA from a BZ(S) and a BZ(R) library) as positive controls. The technique was then extended to the cattle parasites, Cooperia oncophora and Ostertagia ostertagi (from genomic DNA). Sequence analysis proved the presence of amplified BZ(S) alleles in all three species and BZ(R) alleles in the BZ(R) population of H. contortus. Based on these data, nested PCR primers using the diagnostic T or A as the most 3' nucleotide were designed for each species. Conditions for selective PCR were determined. To demonstrate feasibility, genomic DNA was recovered from individual H. contortus L(3) larvae from both BZ(S) and BZ(R) populations. Genomic DNA was also isolated from >70 individual adult male C. oncophora collected from a cattle farm in New Zealand with reported BZ resistance. Allele-specific PCR discriminated among heterozygotes and homozygotes in both species. This method could find utility in studying the molecular epidemiology of BZ resistance in cattle parasites and for defining the variables that limit the development and spread of anthelmintic resistance in this host.
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Banga-Mboko H, Tamboura H, Maes D, Traoré H, Youssao I, Sangild PT, El Amiri B, Bayala B, Remy B, Beckers JF. Survey of gastric lesions and blood pepsinogen levels in pigs in Burkina Faso. Vet Res Commun 2004; 27:595-602. [PMID: 14672448 DOI: 10.1023/a:1027368311808] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The purpose of the study was to investigate the prevalence of gastric lesions and to provide diagnostic values for serum pepsinogen in non-infected pigs and in pigs with gastric disease. In an abattoir survey, the pepsinogen concentrations were measured in the serum from 62 non-infected pigs, 33 pigs with gastric lesions and 17 pigs infected with Hyostrongylus rubidus, using a specific radioimmunoassay (RIA). The mean (+/- SE) pepsinogen concentrations in the serum of non-infected pigs, in pigs with gastric ulcers, and in pigs with a heavy H. rubidus infection were 630.8 +/- 39.2 ng/ml, 1084.5 +/- 166.2 ng/ml and 1095.2 +/- 102.3 ng/ml, respectively (p<0.05). Because of the higher concentrations of pepsinogen in the blood of pigs with gastric ulcers or parasitic infections, it is suggested that the measurement of serum pepsinogen by RIA may be an effective biochemical approach to the diagnosis of chronic gastric disorders in pigs.
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73
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Balic A, Bowles VM, Liu YS, Meeusen ENT. Local immune responses in sensitized sheep following challenge infection with Teladorsagia circumcincta. Parasite Immunol 2004; 25:375-81. [PMID: 14521580 DOI: 10.1046/j.1365-3024.2003.00646.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Sheep were sensitized by weekly infections with Teladorsagia circumcincta over a 9-week period. After a 12-week rest, sheep were divided into four groups and killed without challenge or 3, 5 and 10 days post challenge (DPC) with 50000 L3. Recovery of challenge larvae from abomasal scrapings was highest at 3 DPC while no parasites were recovered by 10 DPC. Abomasal lymph nodes (ALN) of challenged sheep were significantly larger at 5 DPC, coinciding with an increase in the proportion of CD4 T cells and a decrease in CD21+ cells, probably reflecting the loss of CD21 from terminally differentiated antibody secreting cells. A significant increase was observed in gammadelta-TCR+ cells at 3 DPC in the ALN, while their number slightly decreased in the abomasal tissues throughout the challenge period. The number of tissue eosinophils was dramatically increased after challenge compared with the unchallenged controls, with a peak at 3 DPC, coinciding with the peak in larval recovery. CD4+ cells significantly increased in the abomasal tissues at 5 DPC, while no changes in globule leucocytes were observed until 10 DPC. Antibody-secreting cell probes (ASC-probes) generated from the ALN showed highest reactivity against larval antigens at 5 DPC. This reactivity was predominantly directed against regions between 90 and 100 kDa and 30-35 kDa in the L3 preparation and lower molecular weight antigens in the L4. No reactivity was observed against the adult extract. The 30-35 kDa antigen seemed to exist as a high molecular weight complex in L3 homogenate and was not susceptible to protease K treatment, suggesting it may be non-protein in nature.
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Kanobana K, Ploeger HW, Eysker M, Vervelde L. Individual variation and effect of priming dose level on establishment, growth and fecundity ofCooperia oncophorain re-infected calves. Parasitology 2004; 128:99-109. [PMID: 15002909 DOI: 10.1017/s0031182003004268] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We investigated the effect of bovine anamnestic immunity on a range of parasitological variables. To this end, calves were primed with a single oral dose of 30 000 or 100 000 infective larvae (L3) ofCooperia oncophora, drenched with anthelmintic, maintained worm free in the following 2·5 months and subsequently re-infected with 100 000 L3. Parasitological profiles of low, intermediate, and high responders were compared. The reduction in establishment of the worms was shown by a lower worm burden and increased percentage of fourth-stage (L4) larvae. Worm length and fecundity were similarly reduced by both priming doses but, the speed by which the effect occurred differed between animals primed with 30 000 or 100 000 L3. The difference in establishment between the responder types demonstrates that the ability of intermediate responders to mount a more effective and faster immune response compared to low responders is sustained after secondary infection.
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Ruiz de Ybáñez MR, Goyena M, Abaigar T, Garijo MM, Martínez-Carrasco C, Espeso G, Cano M, Ortiz JM. Periparturient increase in faecal egg counts in a captive population of mohor gazelle (Gazella dama mhorr). Vet Rec 2004; 154:49-52. [PMID: 14758830 DOI: 10.1136/vr.154.2.49] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The objective of this study was to assess whether there was a periparturient rise in the faecal egg output of a population of North African gazelles (Gazella dama mhorr) kept in captivity in Almeria, southern Spain. In one experiment faeces were collected from 47 female gazelles on three days in winter, in November and December 1995 and January 1996; in a second experiment faecal samples were collected from nine pregnant gazelles at weekly intervals from July 1996 to June 1997. The mean trichostrongylid faecal egg counts were significantly higher (P < 0.05) in the periparturient gazelles than in the pregnant and non-pregnant animals only when the births took place in winter. Other factors, including the gazelle's age, its level of inbreeding, the number of previous births, and its trichostrongylid egg output at the beginning of the study did not affect whether it showed a periparturient rise. The parasites responsible for the rise were different in the two experiments.
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