Egg Count Reduction Research Articles

Immunomodulatory effects of Moringa oleifera leaves aqueous extract in sheep naturally co-infected with Fasciola gigantica and Clostridium novyi.

The current study was designed to evaluate the in vivo fasciolicidal activity of Moringa (M.) oleifera leaf aqueous extract oral administration as well as its antibacterial activity against Clostridium (C.) novyi in sheep naturally co-infected with fascioliasis and C. novyi. Sheep naturally infected with fascioliasis were divided into 3 groups, heavily infected treated group, lightly infected treated group and mixed infection control (non-treated) group. Treatment groups were orally administered M. oleifera leaves aqueous extract at a dose of 150mg/kg every 48h for 21days. Animal body weights, fecal egg count, serum levels of anti-Fasciola IgG, cytokines (IL-2, IL-17, IL-10), and bacterial count of C. novyi were evaluated. The results showed that treatment with M. oleifera improved the body weight gain and decreased fecal egg count in lightly and heavily infected groups compared to the nontreated group with 100% reduction in egg count in lightly infected sheep. Furthermore, the treatment with M. oleifera significantly reduced the serum levels of IgG, IL-2, and IL-17. Interestingly, elevated levels of IL-10 were recorded in both heavily and lightly infected sheep. The treatment with Moringa extract significantly decreased the fecal bacterial count of C. novyi in both heavily and lightly infected groups. In conclusion, this study highlights the potential beneficial effects of M. oleifera leaf against Fasciola (F.) gigantica and C. novyi.

Identification of the amino acids in the Major Histocompatibility Complex class II region of Scottish Blackface sheep that are associated with resistance to nematode infection

Lambs with the Major Histocompatibility Complex DRB1*1101 allele have been shown to produce fewer nematode eggs following natural and deliberate infection. These sheep also possess fewer adult Teladorsagia circumcincta than sheep with alternative alleles at the DRB1 locus. However, it is unclear if this allele is responsible for the reduced egg counts or merely acts as a marker for a linked gene. This study defined the MHC haplotypes in a population of naturally infected Scottish Blackface sheep by PCR amplification and sequencing, and examined the associations between MHC haplotypes and faecal egg counts by generalised linear mixed modelling. The DRB1*1101 allele occurred predominately on one haplotype and a comparison of haplotypes indicated that the causal mutation or mutations occurred in or around this locus. Additional comparisons with another resistant haplotype indicated that mutations in or around the DQB2*GU191460 allele were also responsible for resistance to nematode infections. Further analyses identified six amino acid substitutions in the antigen binding site of DRB1*1101 that were significantly associated with reductions in the numbers of adult T. circumcincta.

Strategic vaccination of hair sheep against Haemonchus contortus.

In this study, we evaluated in two trials a protocol designed to protect hair sheep using Barbervax®, a vaccine containing Haemonchus contortus gut membrane glycoprotein antigens. Results indicated that naturally infected vaccinated sheep had significant egg count reductions (90.2 ± 4.03%) compared with controls, although blood parameters remained relatively unchanged probably because the level of challenge was low. Vaccination prevented the periparturient rise in egg shedding of ewes, as well as egg shedding in lambs (37.1%). In the second trial, sheep which were experimentally exposed to higher artificial challenge also showed an efficient response to the vaccine as confirmed by high antibody levels and reduced egg counts and worm burdens (87 ± 5.4% and 79%) respectively. Thus, we believe that the vaccine should be integrated with other management practices for meat hair sheep as it has the advantages of adequate efficacy, reducing anthelmintic utilization and avoiding milk and environmental contamination with chemical residues.

Association of MHC class II haplotypes with reduced faecal nematode egg count and IgA activity in British Texel sheep.

Nematode infection is one of the principal diseases suffered by sheep and the class II region of the MHC has been repeatedly associated with differences in susceptibility and resistance to infection. The aim of this study was to examine the association of MHC class II haplotypes in a flock of Texel sheep with faecal egg counts and antibody responsiveness. Two haplotypes carried the DRB1*11:01 allele which has previously been associated with reduced egg counts in Scottish Blackface and Suffolk sheep. One of the two haplotypes was associated with reduced egg counts in the Texel breed, and both haplotypes were associated with reduced IgA activity against an extract from fourth-stage larvae. The reduced IgA activity is probably a consequence of reduced numbers of fourth-stage larvae in sheep carrying the resistance allele. The association of specific MHC alleles with reduced egg counts, reduced worm numbers and decreased IgA activity provides a mechanism for the density-dependent regulation of parasite growth and fecundity.

Natural Selection on Antihelminth Antibodies in a Wild Mammal Population.

An effective immune response is expected to confer fitness benefits through improved resistance to parasites but also incur energetic costs that negatively impact fitness-related traits, such as reproduction. The fitness costs and benefits of an immune response are likely to depend on host age, sex, and levels of parasite exposure. Few studies have examined the full extent to which patterns of natural selection on immune phenotypes vary across demographic groups and environments in the wild. Here, we assessed natural selection on plasma levels of three functionally distinct isotypes (IgA, IgE, and IgG) of antibodies against a prevalent nematode parasite measured in a wild Soay sheep population over 26 years. We found little support for environment-dependent selection or reproductive costs. However, antibody levels were negatively associated with parasite egg counts and positively associated with subsequent survival, albeit in a highly age- and isotype-dependent manner. Raised levels of antiparasite IgA best predicted reduced egg counts, but this did not predict survival in lambs. In adults increased antiparasite IgG predicted reduced egg counts, and in adult females IgG levels also positively predicted overwinter survival. Our results highlight the potential importance of age- and sex-dependent selection on immune phenotypes in nature and show that patterns of selection can vary even among functionally related immune markers.

Changes in Liver Cell Apoptosis after Vaccination by Schistosomulae Antigen and/or Artesunat Treatment in Murine Schistosoma Mansoni

Background and study aim: The target for a schistosoma vaccine or treatment is the reduction in morbidity. The hope for vaccine or treatment is to decrease worm burden and egg pathology to the least percentage, this work aimed to compare between schistosomulae lung stage antigen (SLAP) with and without adjuvant (IL12) and artesunate (ART) treatment regarding their effect especially on liver cell apoptosis. Materials and Methods: Schistosomulae were extracted from the lungs 18 days post infection with Schistosoma mansoni. Eight groups of Swiss albino mice (8 mice each group) were classified as follows: Group A was served as healthy control group, group B was infected with ±100 cercariae and served as infected control group, group C infected then treated by artesunate monotherapy (400mg/kg) single oral dose 6 weeks post infection. ,group D was immunized with 50ug of SLAP then infected,, group E infected then treated by artesunate monotherapy (400 mg/kg) single oral dose 3 weeks post infection, group F was immunized with 50ug of SLAP and 100ug of IL12,group G was immunized with 50ug of SLAP and 100ug of IL12 then infected then treated by artesunate monotherapy (400 mg/kg) single oral dose 6 weeks post infection, group H was immunized with 50ug of SLAP and 100ug of IL12 infected then treated by artesunate monotherapy (400 mg/kg) single oral dose 3 weeks post infection. All groups vaccinated with SLAP vaccine were given booster doses after2 weeks of the first doses. Seven weeks post infection mice were sacrificed for parasitological parameters measurements (worm burden, tissue egg load and oogram pattern), histopathological and immunohistochemical studies using P53 and Bcl-2 markers for determination of liver cells apoptosis. Results and Conclusion: Apoptosis detected by immunohistochemical studies is a good evaluation method. IL12 potentiated the protective effect of SLAP vaccine, ART 3 weeks post infection is better than 6 week post infection in reduction of liver pathology and apoptosis. The combination of both (SLAP+IL12+ART 3 weeks post infection) is the best regarding the reduction of tissue egg count, worm burden, hepatic immunopathology and apoptosis.

Survival of chicken ascarid eggs exposed to different soil types and fungi

The eggs of intestinal ascarid parasites (Ascaridia galli and Heterakis spp.) of chickens can survive long-term in soil and this makes contaminated yards and pastures infective to chickens for years. The fungi Pochonia chlamydosporia Biotype 10 and Metarhizium brunneum KVL04-57 can kill ascarid eggs in agar assays but their efficacy against these eggs in soil is unknown. We therefore initially tested the ovicidal effect of the two fungi in laboratory soil assays. Unembryonated eggs were added to sterilised and non-sterilised soil with or without fungi, and egg recovery was examined before and after incubation (22°C, 30days). Egg recovery was substantially reduced by P. chlamydosporia and M. brunneum in sterilised soil. However, in non-sterilised soil only M. brunneum slightly reduced egg counts. Notably, egg recovery was reduced markedly in non-sterilised soil though no fungi were applied. To test if this is a general characteristic of natural soil, eggs were incubated in similar assays comprising 7 different soils (sterilised and non-sterilised). After incubation, egg recoveries were reduced substantially in all non-sterilised soils whereas there were only minor reductions in sterilised soils. We next isolated and examined if particular egg-degrading fungi occurred in the non-sterilised soil that had exhibited the most extreme ovicidal activity (99%). The fungal isolates belonged to two genera (Metarhizium and Acremonium) with reported egg-degrading properties but when tested in vitro in agar assay, none of the three tested isolates of native fungi degraded >34% eggs, suggesting that these fungi may not individually have caused the reduction in egg survival in the non-sterilised soil. In conclusion, a range of natural soils showed inherent properties related to biotic factors to degrade nematode eggs. The biocontrol efficacy of both P. chlamydosporia Biotype 10 and M. brunneum KVL04-57 was very good in sterilised soil but currently limited in non-sterilised soil, potentially due to competition with natural soil biota in fungal establishment. Further research may determine if efficacy may be increased by changing the formulation.

In vitro and in vivo anthelmintic efficacy of two pentacyclic triterpenoids, ursolic acid and betulinic acid against mice pinworm, Syphacia obvelata.

Pinworm infections are one of the common problems in laboratory rodents and man. At present there are only few drugs against intestinal helminths, and new drugs are urgently needed to cope up any future risk of drug resistance. Interest in plant secondary metabolites (PSMs) has risen considerably in the recent years for the discovery and development of new drugs. In the present study, we explored the in vitro and in vivo anthelmintic potentials of two pentacyclic triterpenoids, ursolic acid (UA) and betulinic acid (BA), the important PSMs of many medicinal plants, against Syphacia obvelata (Nematoda: Oxyuridae), a common pinworm of mice. The results of this study indicated that in both, in vitro and in vivo assays, BA showed comparatively better anthelmintic effects than UA. In the in vitro assay, 1.00mg/ml concentration of BA showed paralysis and mortality of worms in 1.20±0.04 and 2.30±0.03h, respectively. In the in vivo assay, a single 10.00mg/kg dose of BA, administered for 5days, revealed 68.78% reduction in egg counts and 84.08% reduction in worm counts of infected mice. The present study suggests that BA holds a great promise to be pursued further for detailed testing against some other representative group of helminth parasites.

Attempt to control Haemonchus contortus in dairy goats with Barbervax®, a vaccine derived from the nematode gut membrane glycoproteins

The nematode Haemonchus contortus is the most important parasite of small ruminants around the world and the major cause of mortality in tropical regions. Goats are putatively more susceptible than sheep to this parasite and alternatives to anthelmintic utilization are constantly being sought especially after the rise of multiple anthelmintic resistance. Here we present results of a trial designed to evaluate Barbervax®, a vaccine containing gut proteins from Haemonchus contortus, in the control of haemoncosis in dairy goats. In this study female Saanen (n=20) and Anglo Nubian (n=20) goats aged six months were assigned by breed, body weight and fecal egg counts into four experimental groups (n=10) (vaccinated or non-vaccinated). Barbervax® was injected subcutaneously, starting with three priming doses 21days apart followed by boosts every 6 weeks. All animals grazed on the same bushland area and were subjected to natural and artificial worm infection. Mean efficacy over the trial period was 69.8±2.11% and 57.4±2.76% for the Anglo Nubians and Saanens, respectively. Significant differences in packed cell volume (PCV) and total plasma proteins (TPP) values were also observed but only in the Anglo Nubians. The protection afforded by vaccination was considered useful for management of Haemonchus infection in dairy goats by reducing egg counts. Furthermore, the vaccine does not generate chemical residues and could be very interesting for Haemonchus control during milk production.

A nationwide survey of anthelmintic treatment failure on sheep farms in Ireland

BackgroundBetween 2013 and 2015 the Department of Agriculture, Food and the Marine (DAFM) administered a sheep technology adoption programme (STAP), with the aim of increasing profitability on Irish sheep farms by encouraging the adoption of best management practices. One of the options available to STAP participants was to test the efficacy of the anthelmintic treatment (benzimadazole, levamisole or macrocyclic lactone) used in their flocks by means of a drench test, which is a modification of the faecal egg count reduction test; individual faecal samples were collected from the same group of lambs before and after anthelmintic treatment, the number of eggs present pre and post treatment was subsequently determined from a pooled sample.ResultsIn total, 4211 drench tests were undertaken by farmers during the 3 years of the programme. Information on the anthelmintic product used was available for 3771 of these tests; anthelmintics from the classes benzimidazole (BZ), levamisole (LV) and macrocyclic lactone (ML) (avermectins (AVM) plus moxidectin (MOX)) were used in 42.0%, 23.4% and 32.5% of tests, respectively. The remaining 2.1% of tests involved an inappropriate product. The efficacy of treatment against ‘other trichostrongyles’ (excluding Nematodirus spp and Strongyloides papillosus.) could be established for 1446 tests, and 51% of these tests were considered effective (i.e. a reduction of faecal egg count (FEC) ≥ 95%). There was a significant difference among the drug groups in efficacy; 31.5%, 51.9%, 62.5% and 84% of treatments were considered effective for BZ, LV, AVM, MOX, respectively. The efficacy of treatment against Nematodirus spp. could be established for 338 tests and the overall efficacy was 96%.ConclusionsDue to the significant difference among the anthelmintic classes for efficacy against ‘other trichostrongyles’ along with the high level of efficacy against Nematodirus spp., a genus for which anthelmintic resistance is rarely reported, it is concluded that anthelmintic resistance was responsible for the majority of the anthelmintic treatment failures observed.

Anthelmintic resistance status of gastrointestinal nematodes of sheep to the single or combined administration of benzimidazoles and closantel in three localities in Mexico

Veterinaria Mexico OA ISSN: 2448-6760 Cite this as: Alcala Canto Y, Sumano Lopez HS, Ocampo Camberos L, Gutierrez L. Anthelmintic resistance status of gastrointestinal nematodes of sheep to the single or combined administration of benzimidazoles and closantel in three localities in Mexico. Veterinaria Mexico OA. 2016;3(4). doi: 10.21753/vmoa.3.4.374 Sheep production requires the constant assessment of parasitic burden and the efficacy of existing treatments for proper management. In this study, the administration of five different treatments was evaluated for the reduction of the percentage of eggs per gram of feces (EPG) shed by gastrointestinal nematodes (GIN) from sheep on three different sheep-breeding farms in Mexico (Texcoco, Estado de Mexico; Hueytamalco, Puebla; and Tlaltizapan de Zapata, Morelos). In these farms, ivermectin and benzimidazole derivatives had been routinely administered for two consecutive years. To determine whether drugs with different pharmacological properties decreased GIN fecal egg excretion, the treatments closantel (CLOS), albendazole (ABZ) and fenbendazole (FBZ) were administered alone and in combinations of CLOS + ABZ and CLOS + FBZ, to five groups of sheep, with an additional untreated control group on each farm (n = 28 per flock). Anthelmintic resistance was determined using Fecal Egg Count Reduction Tests (FECRT) as recommended in the guidelines of the World Association for the Advancement of Veterinary Parasitology. Fecal samples were collected 14 and 21 days after treatment. The anthelmintic resistance status was determined based on the reduction in the fecal egg count arithmetic mean and 95 % confidence limits. According to the FECRT, resistance developed to CLOS, ABZ, FBZ and CLOS + FBZ because the mean percentage of EPG reduction was ≤ 95 % with a lower confidence limit of ≤ 90 %. By contrast, nematode susceptibility was confirmed for the CLOS + ABZ combination, as it reduced the percentage of GIN fecal egg output by 96.46 ± 3.04 % (day 14) and 96.88 ± 3.04 % (day 21). Based on the morphometric identification of larvae, Haemonchus spp., Cooperia spp. and Teladorsagia spp. were the most abundant genera on all farms before the administration of these five treatments. In conclusion, the use of the anthelmintic combination of closantel plus albendazole may reduce the development of anthelmintic resistance in gastrointestinal nematodes. Figure 1. Marginal means ± SD of the percentage reduction in egg count on days 14 and 21 after treatment of sheep on three farms (n = 28 per flock) with fenbendazole (FBZ), closantel (CLOS), albendazole (ABZ), closantel + fenbendazole (CLOS + FBZ) and closantel + albendazole (CLOS + ABZ).

In vitro and in vivo anthelmintic activities of Iris kashmiriana Linn.

In search of a natural antiparasitic, in vitro and in vivo anthelmintic activities of methanol and aqueous extracts of Iris kashmiriana Linn. rhizome were tested against gastrointestinal nematodes of sheep. A worm motility inhibition assay was used for in vitro study and a faecal egg count reduction assay was used for in vivo study. Crude aqueous extracts of I. kashmiriana exhibited greater anthelmintic activity against Haemonchus contortus than crude methanolic extract (P<0.05). The aqueous extracts of I. kashmiriana resulted in a mean worm motility inhibition of 85.0%, while methanolic extracts resulted in a mean worm motility inhibition of 100.0%. The in vivo anthelmintic activity of aqueous and methanolic extracts of I. kashmiriana in sheep naturally infected with mixed gastrointestinal nematodes species demonstrated a maximum (70.27%) egg count reduction in sheep treated with aqueous extracts at 2gkg−1 body weight on day 15 after treatment, closely followed by methanolic extracts at 1gkg−1 body weight on day 15 after treatment (33.17% egg count reduction) while as lethal concentration (LC50) values of aqueous and methanolic extracts of I. kashmiriana on adult worms of gastrointestinal nematodes of sheep H. contortus are 18.50mg/ml and 16.66mg/ml respectively. Thus aqueous extracts exhibited greater anthelmintic activity under both in vitro and in vivo conditions; this could be due to the presence of water soluble active ingredients in I. kashmiriana. From the present study it can be suggested that I. kashmiriana rhizome exhibited significant anthelmintic activity against gastrointestinal nematodes of sheep and has the potential to contribute to the control of gastrointestinal nematode parasites of small ruminants.

Hamsters vaccinated with Ace-mep-7 DNA vaccine produced protective immunity against Ancylostoma ceylanicum infection

Hookworms are intestinal nematodes that infect up to 740 million people, mostly in tropical and subtropical regions. Adult worms suck blood from damaged vessels in the gut mucosa, digesting hemoglobin using aspartic-, cysteine- and metalloproteases. Targeting aspartic hemoglobinases using drugs or vaccines is therefore a promising approach to ancylostomiasis control. Based on homology to metalloproteases from other hookworm species, we cloned the Ancylostoma ceylanicum metalloprotease 7 cDNA (Ace-mep-7). The corresponding Ace-MEP-7 protein has a predicted molecular mass of 98.8 kDa. The homology to metallopeptidases from other hookworm species and its predicted transmembrane region support the hypothesis that Ace-MEP-7 may be involved in hemoglobin digestion in the hookworm gastrointestinal tract, especially that our analyses show expression of Ace-mep-7 in the adult stage of the parasite. Immunization of Syrian golden hamsters with Ace-mep-7 cDNA resulted in 50% (p < 0.01) intestinal worm burden reduction. Additionally 78% (p < 0.05) egg count reduction in both sexes was observed. These results suggest that immunization with Ace-mep-7 may contribute to reduction in egg count released into the environment during the A. ceylanicum infection.

Short Communication: Birdsfoot trefoil as a preventative treatment for gastrointestinal nematodes in pastured dairy heifers

Shepley, E., Vasseur, E., Bergeron, R., Villeneuve, A. and Lachance, S. 2015. Short Communication: Birdsfoot trefoil as a preventative treatment for gastrointestinal nematodes in pastured dairy heifers. Can. J. Anim. Sci. 95: 533–537. Bioactive forages, such as birdsfoot trefoil, may serve as an alternative to anthelmintic drugs in pastured dairy heifers. Differences in parasite burden and growth were examined between eight treatment heifers fed a birdsfoot trefoil mixture and nine control heifer fed alfalfa silage 45-min per day for 12 wk. A significant 3.8- to 9.4-fold reduction in fecal egg counts was observed for treatment heifers at weeks 5, 9, 11 and 12. No treatment effect was found for weight gain. Our results suggest that birdsfoot trefoil may reduce parasite fecal egg counts in pastured dairy heifers without detrimental impact on growth.

Efficacy and safety of oxantel pamoate in school-aged children infected with Trichuris trichiura on Pemba Island, Tanzania: a parallel, randomised, controlled, dose-ranging study

Commonly used drugs for preventive chemotherapy against soil-transmitted helminths (ie, albendazole and mebendazole) show low efficacy against Trichuris trichiura. Recent studies with oxantel pamoate revealed good cure rates and high egg-reduction rates against T trichiura. We aimed to assess the nature of the dose-response relation to determine the optimum dose. We did a parallel, randomised, placebo-controlled, single-blind trial with oxantel pamoate in school-aged children (aged 6-14 years) infected with T trichiura on Pemba Island, Tanzania. Children were asked to provide two stool samples and children positive for T trichiura were eligible to participate in the trial. Children were excluded if they suffered from any systematic illness. Children were randomly assigned to six different oxantel pamoate doses (5-30 mg/kg) or a placebo. Randomisation was stratified by baseline infection intensity using random block sizes of seven and 14. The primary endpoints were cure rates and egg-reduction rates against T trichiura, both analysed by available case. Drug safety was assessed 2 h and 24 h after treatment. The trial is registered at www.isrctn.com, number ISRCTN86603231. Between Oct 14, and Nov 28, 2014, we enrolled 480 participants and randomly assigned 350 children to the different oxantel pamoate doses or the placebo. 5 mg/kg oxantel pamoate was the minimum effective dose (10 of 46 children cured [cure rate 22%, 95% CI 11-36]; egg-reduction rate 85·0%, 64·5-92·9). An increased probability of being cured and reduced egg counts with escalating doses was recorded. At 25 mg/kg oxantel pamoate 27 of 45 children were cured (cure rate 60%, 95% CI 44-65) with an egg-reduction rate of 97·5% (94·4-98·9), and at 30 mg/kg 27 of 46 children were cured (59%, 43-73) with an egg-reduction rate of 98·8% (96·8-99·6). Oxantel pamoate was well tolerated across all treatment groups; only mild adverse events were reported by the participants 2 h (27 [10%]) and 24 h (12 [4%]) after treatment. Our dose-finding study revealed an excellent tolerability profile of oxantel pamoate in children infected with T trichiura. An optimum therapeutic dose range of 15-30 mg/kg oxantel pamoate was defined. With a weight independent dose of 500 mg oxantel pamoate 95% of children aged 7-14 years in sub-Saharan Africa would receive doses of 11·7-32·0 mg/kg. Future research should include studies with oxantel pamoate in younger children and on different continents with the ultimate goal to be able to add oxantel pamoate to soil-transmitted helminth control programmes. Swiss National Science Foundation.

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.

Eficacia de la doramectina vía intramuscular en nematodos gastrointestinales en equinos

El objetivo de esta investigación fue comprobar la efectividad de la doramectina vía intramuscular frente a los nematodos de equinos, al evacuarla según la reducción en el conteo de huevos por gramo de materia fecal (hpg). Para tal fin se utilizaron seis asnos y diez caballos mestizos de silla de diferentes sexos y edades, todos naturalmente infectados con nematodos gastrointestinales, los que aleatoriamente se dividieron en dos grupos: el 1 (control), tres asnos y cuatro caballos que no recibieron tratamiento antihelmíntico; y el 2 (tratados), tres asnos y seis caballos tratados con doramectina a dosis de 0,2 mg/kg vía intramuscular, dosis única, aplicada en la tabla del cuello. A los días 5, 12, 16, 24, 34, 41, 47, 56, 60 y 140 postratamiento se sometieron todos los animales a exámenes coprológicos, lo que permitió definir los valores de hpg por medio de la técnica de McMaster. Los resultados determinaron que la doramectina utilizada vía intramuscular fue altamente eficaz para controlar nematodos bajo condiciones de campo y en animales sometidos a continuas reinfestaciones.

Status of anthelmintic resistance in goats maintained under field and farm conditions in chhattisgarh plain

In the present study, field goats in Chattisgarh Plain exhibited 100, 99 and 100% reduction in faecal egg counts with albendazole, levamisole and ivermectin, respectively and lower 95% confidence limit was 98% in all treatment groups. This indicates susceptibility of nematode parasites of field towards all three groups of anthelmintics. On the contrary, farm goats exhibited resistance against benzimidazoles (FECR-94% and lower 95% confidence limit-68%) while levamisole and ivermectin showed 100% efficacy with lower 95% confidence limit of 96 and 99%, respectively. The dominant nematode parasite exhibiting resistance was Haemonchus spp. On egg hatch assay, ED50 value of field goats was 0.0310μg TBZ ml−1 and that of farm was 0.1500μg TBZ ml−1 further confirms emergence of benzimidazole resistance in farm goats.

Immune response of lambs experimentally infected with Haemonchus contortus and parenterally treated with a combination of zinc and copper

Haemonchus contortus parasite causes high mortality rates and drastic productivity reduction besides enhancing treatment costs. It has also been demonstrating great resistance against most of the drugs currently in use. Thus, the utilization of elements that can boost the host immune response to cope with the infection has been widely studied. Some researchers have shown that the use of zinc (Zn) and copper (Cu) as nutritional supplements can help controlling the parasites. The present study evaluated the immune response of lambs experimentally infected with H. contortus and treated with Zn and Cu. Twenty-one (21) lambs were divided into three groups: CG (non-infected control group), IG (infected group – infection performed with 15,000 larvae of H. contortus/animal) and ITG (group infected and treated subcutaneously with 1.5mg/kg of Zn and 0.45mg/kg of Cu on days 10 and 45 post-infection [PI]). Blood samples were drawn on days 0, 14, 28, 42, 56 and 70 PI in order to determine the serum concentrations of interleukin 1 (IL-1), interleukin 4 (IL-4) and interleukin 6 (IL-6), interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) and immunoglobulins (Igs) IgA, IgE, IgG and IgM. The parasitic infection was monitored by the counting of eggs per gram of feces (EPG) in the same intervals of blood sampling. At the end of the experiment, animals were euthanatized and the parasite load was quantified. In addition, the concentrations of Zn and Cu in liver were assessed. A significant increase in EPG was observed only on day 14 PI for IG and ITG (P<0.05). Between days 14 and 42 there was a significant increase (P<0.001) of cytokine and immunoglobulin levels in IG and ITG, when compared with the animals of CG. After day 56, the IG animals showed serum level of interleukins and immunoglobulins lower than ITG animals (P<0.001). Regarding the liver concentrations of Zn and Cu, the infection showed to lead a depletion of these minerals; therefore, the supplementation did not prevent this effect. The results of this study indicate that the administration of Zn and Cu was capable of enhancing the immune response in lambs experimentally infected with H. contortus. However, it did not reduce egg counts in the feces or the number of adult parasites in the abomasum.

Lack of efficacy of monepantel against Teladorsagia circumcincta and Trichostrongylus colubriformis

After reports of the apparent failure of monepantel to reduce the egg counts of goats on a farm in the lower North Island of New Zealand, faecal egg count reduction tests were conducted in goats and lambs resident on the property, and a confirmatory, slaughter study was conducted using 12 sheep, sourced elsewhere, that were grazed on the farm for approximately 5 weeks. In the egg count reduction test in goats, 8 animals were given monepantel at 3.9mg/kg (just over 1.5× the sheep dose rate of 2.5mg/kg), whilst four received 7.7mg/kg (just over 3× the sheep dose). In the egg count reduction test in sheep, 15 lambs were treated with 3.0mg/kg of monepantel. For the confirmatory study, the sheep were housed indoors for 2 weeks before half were treated with 2.9mg/kg monepantel and the animals were killed for worm counts 9 days later. There was no evidence of efficacy in either egg count reduction test, or in the goats, the two dose rates used appeared equally ineffective. Likewise, there were no significant reductions in egg counts or worm burdens in the slaughter study. Monepantel was ineffective against at least two gastrointestinal nematode species, Teladorsagia circumcincta and Trichostrongylus colubriformis. These findings represent the first report from the field of resistance having developed to the anthelmintic monepantel with severe resistance developing in more than one species after being administered on 17 separate occasions to different stock classes and in less than 2 years of the product first being used on the farm in question.