Post-treatment Faecal Egg Counts Research Articles

Multigeneric resistance to monepantel on a UK sheep farm

The amino acetonitrile derivative, monepantel, represented the first new broad spectrum anthelmintic to be brought to market for use in sheep for over 25 years when it was introduced in 2009. This study characterised monepantel efficacy, using faecal egg count reduction and controlled efficacy tests, against gastrointestinal nematodes following a report of treatment failure in a UK lowland sheep flock. Twelve lambs were each artificially administered 15,000 infective larvae that had been propagated from lamb faeces collected from the farm of interest. The controlled efficacy test showed that a recommended dose rate of monepantel (2.5 mg/kg body weight) administered at day 28 post infection was ineffective at removing the infection in the treated lambs. The result demonstrated simultaneous resistance to monepantel in Teladorsagia circumcincta, Trichostrongylus vitrinus and Oesophagostomum venulosum with efficacies based on adult worm burden reductions, compared to untreated controls, of 78%, 27% and 22% respectively. Monepantel efficacy based on undifferentiated egg count in treated animals, seven day post administration, compared to untreated controls was 85%. The results raise questions about the origins of, and predisposing factors for, resistance development in the three different species, and reinforces the value of differentiating post treatment faecal egg counts to genus or species level.

Anthelmintic resistance to cattle gastrointestinal nematodes in selected dairy farms of Mymensingh and Sirajganj districts of Bangladesh

Correction: Table 1 and Table 2 have were omitted from the PDF in error. They were added to page 89 on 17th May 2018.Anthelmintic resistance (AR) to commonly used dewormers is one of the major world-wide constrain in livestock production. The present study was investigated the status of AR in BAU dairy farm, Mymensingh and Talukder dairy farm, Sirajganj. Faecal egg count reduction test (FECRT) was applied to assess AR in cattle of two dairy farms during January to June 2017. The anthelmintics tested were Albendazole (ABZ), a benzimidazole anthelmintic (Almex®, Square Ltd.) and Ivermectin (IVM) (Vermic®, Techno drugs Ltd.), administered at the doses recommended by the manufacturers. In each farm, cattle were divided into treatment and control (not treated) group based on faecal egg counts (FEC), that is at least 200 eggs/g. At 14 days after treatment, faecal samples were collected for post-treatment FEC, which is compared between treatment and control group. Resistance was defined if there was <95% reduction, with lower 95% confidence limit (CL) <90% in the FEC. AR was present in both the dairy farms involved in this study. The FECRT using ABZ revealed 79.7% (95% CL 87.9, 65.8) reduction and 95.8% (95% CL 98.7, 87.1) reduction of FEC in BAU and Talukder dairy farms, respectively. Also, FECRT using IVM revealed 77.9% (95% CL 97.7, 85.5) and 94.2% (95% CL 97.7, 85.5) reduction of FEC in BAU and Talukder dairy farms, respectively. Our study suggest that AR is present in both selected dairy farms and further extensive studies are required to determine the extent of AR in different cattle farms of Bangladesh.Res. Agric., Livest. Fish.5(1): 87-92, April 2018

Gastrointestinal parasites of captive European bison Bison bonasus (L.) with a sign of reduced efficacy of Haemonchus contortus to fenbendazole.

The history of European bison Bison bonasus Linnaeus, 1758 has been stormy since its extinction in the wild after the First World War. Due to the fact that the species was restored from just 12 founders, further expansion has suffered from low genetic variability, rendering the bison vulnerable to various pathogens due to inbreeding depression. Parasites are recognised as a key biological threat to bison population. Thus, parasitological examination including monitoring of the level of anthelmintic resistance in a herd should be a routine procedure involved in management and protection of European bison. This study was conducted in a group of 27 bison kept in a European bison breeding centre in Sweden. In April 2015, a faecal egg count reduction test (FECRT) was performed in animals with ≥100 gastrointestinal nematode (GIN) eggs per gram faeces, to determine effectiveness of fenbendazole (FBZ) treatment. Additionally, the third stage larvae were cultured for molecular examination by a conventional PCR as well as by real-time quantitative PCR (q-PCR) for detection of the blood-sucking nematode Haemonchus contortus. Faecal sampling was conducted 1day before and 8days after deworming each animal. Anthelmintic treatment turned to be entirely efficient toward intestinal nematodes of genera Nematodirus and Trichuris, whereas shedding of strongylid eggs from the subfamily Ostertagiinae was reduced from 81 to 30%. Polymerase chain reaction (PCR) on cultured third-stage larvae (L3) before treatment was positive for H. contortus, Ostertagia ostertagi and Cooperia oncophora, whereas post-treatment examination revealed exclusively the DNA of H. contortus. Thus, only H. contortus was involved in post-treatment faecal egg count (FEC). FECRT showed that the reduction in strongylid FEC to FBZ in the examined bison herd was 87% (95%-confidence intervals [95% CI] =76-93), suggesting reduced efficacy of FBZ to strongylid GIN including mainly H. contortus.

Anthelmintic resistance to ivermectin and moxidectin in gastrointestinal nematodes of cattle in Europe

Anthelmintic resistance has been increasingly reported in cattle worldwide over the last decade, although reports from Europe are more limited. The objective of the present study was to evaluate the efficacy of injectable formulations of ivermectin and moxidectin at 0.2 mg per kg bodyweight against naturally acquired gastro-intestinal nematodes in cattle. A total of 753 animals on 40 farms were enrolled in Germany (12 farms), the UK (10 farms), Italy (10 farms), and France (8 farms). Animals were selected based on pre-treatment faecal egg counts and were allocated to one of the two treatment groups. Each treatment group consisted of between 7 and 10 animals. A post-treatment faecal egg count was performed 14 days (±2 days) after treatment. The observed percentage reduction was calculated for each treatment group based on the arithmetic mean faecal egg count before and after treatment. The resistance status was evaluated based on the reduction in arithmetic mean faecal egg count and both the lower and upper 95% confidence limits. A decreased efficacy was observed in half or more of the farms in Germany, France and the UK. For moxidectin, resistance was confirmed on 3 farms in France, and on 1 farm in Germany and the UK. For ivermectin, resistance was confirmed on 3 farms in the UK, and on 1 farm in Germany and France. The remaining farms with decreased efficacy were classified as having an inconclusive resistance status based on the available data. After treatment Cooperia spp. larvae were most frequently identified, though Ostertagia ostertagi was also found, in particular within the UK and Germany. The present study reports lower than expected efficacy for ivermectin and moxidectin (based on the reduction in egg excretion after treatment) on European cattle farms, with confirmed anthelmintic resistance on 12.5% of the farms.

Resistance of gastrointestinal nematodes to the most commonly used anthelmintics in sheep, cattle and horses in Spain

The objective of this study was to evaluate the status of anthelmintic resistance (AR) in ruminants and horses in Spain. The efficacy of commonly used macrocyclic lactones (MLs) – ivermectin (IVM) and moxidectin (MOX) – was measured in sheep, cattle and horses. In addition, albendazole (ABZ) and levamisole (LEV) were evaluated in sheep and oxibendazole (OXI) and pyrantel (PYR) in horses. Efficacy was evaluated based on the difference between the arithmetic mean pre- and post-treatment faecal egg count (in cattle and horses), or compared to an untreated control group (in sheep). AR was present when the percentage reduction in egg count was <95% and the lower 95% confidence interval (CI) was <90%; if only one of these two criteria was met, the finding was recorded as suspected AR (SAR). In horses, AR–PYR and OXI was considered when the percentage reduction in egg count was ≤90% and the lower 95% CI was ≤80%. For each animal species, at least 10 study sites were selected.AR to at least one of the drugs was detected in all 10 sheep flocks; the main parasite identified after treatment was Teladorsagia circumcincta. Moreover, in 5 flocks multidrug resistance was identified, on 4 farms to drugs from different families, on one farm to both MOX and IVM and on another farm to all drugs tested. In cattle, the efficacy of both MOX and IVM was 100% on 4 and 3 farms, respectively, and therefore 60% of these farms were considered to have AR or SAR to both MLs. The most frequent parasite identified after treatment was Trichostrongylus spp., although Ostertagia ostertagi was also identified after treatment on one farm. In contrast to ruminants, the 4 drugs evaluated in horses were highly efficacious against strongyles, with efficacies for the MLs and OXI between 95 and 100% and between 94 and 100% for PYR, although 3 herds were SAR against PYR.In conclusion, AR to at least one of the commonly used drugs was identified on all sheep flocks investigated in the northwest of Spain. The occurrence of AR to MLs in cattle was higher than expected but consistent with what was observed in sheep. In horses, all currently used drugs were confirmed as effective against strongyles.

Findings from an ovine parasitological monitoring service provided by a rural veterinary practice in New South Wales, Australia.

To describe an ovine parasitological monitoring service delivered by a rural veterinary practice and determine associations between flock, anthelmintic and monitoring factors and worm control. Retrospective study of records from a rural veterinary practice in south-eastern Australia over an 8.75-year period. Records of sheep producers using veterinary services for gastrointestinal parasite management from 1 August 2003 to 30 April 2012 were analysed. Results from pre- (FECt1 ) and post-treatment faecal egg counts (FECt2 ) were used to identify factors influencing anthelmintic effectiveness, calculated as faecal egg count reduction percentage (FECR%) by linear mixed model analyses. The trends in anthelmintic merchandising and uptake of veterinary services for parasite management were determined by logistic regression analyses. FECR% varied according to the treatment group used (P < 0.001), with an apparent decreasing effectiveness of the macrocylic lactone group over the duration of the study (P = 0.008). Wether and ram flocks displayed lower FECR% than ewe flocks (P < 0.05). Time between FECt1 and treatment (P = 0.031), as well as time between treatment and FECt2 (P < 0.001), had a significant negative association with FECR%. The proportion of properties purchasing 4-way combination anthelmintics increased significantly over the study period (P < 0.001), with declines observed in other anthelmintics (P < 0.05). The proportion of properties performing FECR% monitoring to those that purchased anthelmintics increased significantly over the study period (P = 0.001). Anthelmintic treatment type, sex of the flock and time between drenching and testing had the greatest influence on drench effectiveness (FECR%). An increasing reliance on 4-way combination drenches to manage gastrointestinal parasitism was demonstrated. Benefits of parasitological monitoring include: appropriate advice on parasitological management; observations on trends in regional anthelmintic usage; estimation of drench effectiveness; early indication of anthelmintic resistance; and improved service provision by the rural veterinary practice.

Further studies on the necessity or otherwise of multiple pre-treatment groups in faecal egg count reduction tests in sheep

Data utilised in a previous study to compare two different faecal egg count reduction tests (FECRTs) in sheep involving multiple anthelmintic treatments and undifferentiated faecal egg counts (FECs), were re-examined using FECs for individual parasite genera. The first of these FECRTs was based on changes in the pre- and post-treatment FECs of the same groups of animals. The other represented an abbreviated version of the former procedure and involved only a single common pre-treatment group as a baseline for comparing all post-treatment results. A comparison of the results obtained with these two procedures showed that the use of either one of them was likely to provide similar estimates of anthelmintic efficacy and the detection of a comparable number of cases of anthelmintic-resistance for all parasite genera. These findings offer further support to a previously expressed view that the use of the more complex and costly pre- and post-treatment FECRT procedure is unlikely to provide any real advantages over the simpler one.

Are multiple pre-treatment groups necessary or unwarranted in faecal egg count reduction tests in sheep?

Previously conducted faecal egg count reduction tests (FECRTs) in sheep involving a number of different anthelmintic treatments, were used to examine the effects of comparing post-treatment faecal egg counts (FECs) with pre-treatment counts from either the same treatment groups (matched FECRs) or with those from other treatment groups (unmatched FECRs). Each of these unmatched FECRs were considered to be analogous to those that might otherwise have been obtained by the use of a randomly selected group of animals to provide a single pre-treatment baseline for comparing all post-treatment results. An examination of these comparisons showed that the use of either procedure was likely to result in similar estimates of anthelmintic efficacy and the detection of a comparable number of cases of anthelmintic-resistance. Only on 1.1% of occasions did the FECRs from any of the unmatched groups fall outside the 95% confidence limits of the FECRs of their corresponding matched counterparts and in just 9.8% (54/553) of instances were there any disagreements between the number of cases categorised as either resistant or susceptible on the basis of a < or ≥95% FECR. These findings suggest that any improvements in accuracy and reliability that might supposedly be achieved by the use of multiple pre- and post-treatment FECs from the same treatment groups as opposed to those likely to be provided by the use of a single randomly selected representative pre-treatment group, may be largely illusory.

Intestinal and lung parasites in owned dogs and cats from central Italy

Prevalence and risk factors of intestinal and lung parasites were investigated in 239 owned dogs and 81 owned cats from central Italy. In 36 dogs and 20 cats found infected by nematodes, pre and post-treatment faecal egg count (FEC) was also evaluated. About 31% of dogs and about 35% of cats resulted positive for at least one intestinal or lung parasitic species. Helminthic, intestinal and zoonotic infections resulted prevalent in examined animals. Examined dogs resulted infected by Toxocara canis (13.0%), Toxascaris leonina (1.7%), Trichuris vulpis (3.3%), Ancylostoma caninum (2.0%), Uncinaria stenocephala (1.25%), Strongyloides stercoralis (0.8%), Angiostrongylus vasorum (0.4%), Dipylidium caninum (1.25%), Taeniidae eggs (0.4%), Giardia duodenalis (3.8%), and Cystoisospora (Isospora) spp. (7.5%). Examined cats were infected by Toxocara cati (22.2%), Capillaria aerophila (1.2%), Ancylostoma tubaeformae (1.2%), U. stenocephala (3.7%), Aelurostrongylus abstrusus (1.2%), Mesocestoides sp. (1.2%), D. caninum (1.2%), G. duodenalis (1.2%) and Cystoisospora spp. (4.5%). The presence of clinical signs and the young age (less than 6 months) were identified as risk factors by univariate and multivariate statistical analysis. In 63.9% treated dogs and in 80.0% treated cats, percentages of post-treatment FEC reduction higher than 90% were found. Results obtained in this study are discussed.

Efficacy of levamisole and ivermectin in the control of bovine parasitic gastroenteritis in the sub-humid savanna zone of southeastern Nigeria

Faecal egg count reduction test was used to evaluate the efficacy of levamisole and ivermectin in the control of bovine parasitic gastroenteritis in a part of Nigeria not previously surveyed. Ninety (90) randomly selected N'dama cattle from two herds in Nsukka, Enugu State of Nigeria, were studied. The animals were divided into two groups, namely, levamisole and ivermectin treatment groups. Faecal samples were collected prior to the administration of the respective anthelmintic and faecal egg count/gram of faeces determined. Post-treatment faecal samples were collected after 10 and 14 days of levamisole and ivermectin administration, respectively, and faecal egg count (FEC) determined. Thereafter, the faecal egg count reduction was calculated based on the formula [Formula: see text]. Pooled faecal samples for the respective treatment groups were cultured for larval identification and count. Pre-treatment FEC showed that the animals were readily infected with gastrointestinal nematodes with mean FEC of 233.0 ± 35.13 and 302.0 ± 19.94, respectively, for the levamisole- and ivermectin-treated groups. Post-treatment FEC of 0 was recorded for both groups, showing a 100% reduction of the pre-treatment faecal egg count. We concluded that the anthelmintics used in this work were very effective in the control of bovine parasitic gastroenteritis in the study areas, and no resistance was detected.

Tactical treatment with copper oxide wire particles and symptomatic levamisole treatment using the FAMACHA© system in indigenous goats in South Africa

Haemonchosis is considered to be the most economically important gastrointestinal disease of small ruminants in the tropics and subtropics. However, chemical anthelmintics, which were the mainstay of control, have been compromised by a high prevalence of resistance worldwide. Copper oxide wire particles (COWP) have been shown to have anthelmintic effects, but few studies have examined their use under field conditions. The use of COWP was therefore evaluated as a tactical anthelmintic treatment in indigenous goats raised under communal farming conditions in Bergville, KwaZulu-Natal Province, South Africa. At the beginning of the summer rainfall season (October 2007), the faecal egg counts of 172 female goats belonging to 15 farmers were determined and this sampling continued every four weeks until the second week of January 2008. The goats within each of the 15 herds were ranked according to their faecal egg counts for this week. The goats were sequentially paired off within each ranking starting with those goats with the highest counts. One goat from each pair was randomly allocated to a treated or control group. Two weeks later, a 4g COWP bolus was randomly administered to each goat in the treated group. Faecal egg counts were carried out on the goats two weeks following treatment, and the sampling of the goats then proceeded every four weeks until October 2008. Except for the six-week period prior to the administration of the COWP, the goats were examined according to the FAMACHA© system and symptomatically treated with 12mg/kg levamisole when anaemic. The percentage reduction in faecal egg count due to the COWP treatment was 89.0%. Mean pre- and post-treatment faecal egg counts for the COWP-treated group (n=73) were 2347 eggs per gram of faeces (epg) and 264epg, respectively. The corresponding values for the untreated controls (n=66) were 2652epg and 2709epg. The prevalence of Haemonchus spp. larvae in pre- and post-treatment faecal cultures was 72% and 46%, respectively. Symptomatic anthelmintic treatments in combination with mid-summer tactical treatments with COWP appear to be useful strategies for the control of Haemonchus contortus in indigenous goats in this farming system and this approach could have application in other similar agro-ecological zones.

Faecal Cyathostomin Egg Count distribution and efficacy of anthelmintics against cyathostomins in Italy: a matter of geography?

BackgroundIn the framework of a trial carried out in 2008 in Europe to evaluate the efficacy of major parasiticides against horse cyathostomins, pre- and/or post-treatment Faecal Egg Counts (FEC) were evaluated in a total of 84 yards and 2105 horses from nine different regions from the South, the Center, the North-Center and North-East of Italy. Specifically, on the basis of FECs of the horses present in each property, 60 out of the 84 yards were enrolled for a Faecal Egg Count Reduction Test (FECRT) using fenbendazole, pyrantel, ivermectin and moxidectin.ResultsOf the 1646 horses bred in the 60 recruited yards, 416 animals had a FEC between 50 and 150 Eggs Per Gram (EPG) of faeces and 694 a FEC >150 EPG (i.e. with total of 1110 positive animals). Of the 1110 positive animals, those with the highest FECs (i.e. 988) were included in the FECRT. The FECRT for four anthelmintic compounds showed remarkable differences in terms of prevalence of reduced and equivocal efficacy against cyathostomins in the different areas of Italy. Administration of fenbendazole and pyrantel resulted in resistance present or suspected in about half of the yards examined while resistance to ivermectin was found in one yard from central Italy and suspected resistance was detected in three more yards, one in each the North, the Center and the South. Treatment with moxidectin was 100% effective in all yards examined.ConclusionCyathostomin populations in the South and the Center of Italy were more susceptible to fenbendazole and pyrantel than the populations present in the Center-North and North-Eastern areas of Italy. Fenbendazole and/or pyrantel were ineffective in almost all properties from the North of Italy. The reasons for such a difference among the Italian regions in terms of FECs and efficacy of antiparasitic drugs are discussed, together with the role that veterinarians, and horse owners and managers should have for effective worm control programs in this country.

Anthelmintic activity of ivermectin against experimental Ascaridia galli infection in chickens

The efficacy of ivermectin against Ascaridia galli infection was evaluated in chickens under controlled laboratory conditions in two separate experiments. In each experiment 22 White Leghorn chicks were randomly assigned to three groups of 10 (infected-treated), 9 (infected-control) and 3 (uninfected-control) birds. Each bird in the former two groups was orally infected with 1500 embryonated A. galli eggs. The chicks in the treated group were subcutaneously injected with ivermectin at a dose of 0.3 mg kg −1 body weight on Day 10 (Experiment 1) and Day 35 post-infection (Experiment 2) for immature and adult infections, respectively. The treated birds had 0.9% (Experiment 1) and 0.4% (Experiment 2) worm recovery compared with 8.7 and 8% in the infected-untreated controls of the respective experiments. The fall in post-treatment faecal egg counts was 81 and 92% in birds treated on Days 10 and 35, respectively. The drug was found to be 90 adn 95% effective against immature and adult worms, respectively. The lower lesion score and post-treatment near-normal haematobiochemical picture in treated birds confirmed these observations. The treated birds also had a better growth rate than the untreated chickens. The mature worms in the intestinal lumen of the host were more sensitive to the treatment than the immature stages of the parasite in the tissue phase.

Effects of a preventive and suppressive control scheme on the development of thiabendazole-resistance in Ostertagia spp.

Three years after the start of an experiment to assess the merits of thiabendazole (TBZ) treatment of trichostrongylid parasites in weaner sheep, field isolates of Ostertagia spp and Trichostrongylus spp were made from weaner sheep treated under one of three treatment schemes. Treatment frequencies were "nil", "planned" (5 or 6/year) and "regular" (every 3 weeks). In addition an isolate was taken from a group of "tracer" sheep drenched with TBZ every 10 days. Resistance to TBZ was assessed using an in vitro egg hatch assay, pre- and post-treatment faecal egg counts and a controlled anthelmintic efficiency test. Pre- and post-treatment egg counts revealed the presence of TBZ-resistance in field isolates of mixed species. Egg hatch assays indicated a level of resistance for Ostertagia spp which was proportional to the frequency of TBZ treatment. The "planned", "regular" and "tracer" strains of Ostertagia spp had resistance ratios for eggs of 4, 13 and 15 respectively when compared to the "nil" strain. In the anthelmintic efficiency assay treatment with 44 mg kg-1 and 88 mg kg-1 of TBZ removed 82 and 96% respectively of the total Ostertagia burden (adults and larvae) from the "nil" strain and 30 and 75% respectively from the "planned" strain. The same dose rates against the "regular" and "tracer" strains and additional rates of 132 or 176 mg kg-1 against the "tracer" strain failed to reduce the Ostertagia burden significantly. Intestinal Trichostrongylus spp from all isolates were fully susceptible to TBZ at 44 mg kg-1. Levamisole at 7.0 mg kg-1 was highly effective (99% reduction) against the "tracer" strain of Ostertagia.