Serum antibody responses in Creole kids experimentally infected with Haemonchus contortus

The objective of this study was to evaluate the relationship of parasite-specific serum antibodies with the resistance status of Creole kids. The average breeding values on egg output predicted in a context of natural infection at 11 months of age were distant of 1.07 genetic standard deviation between resistant and susceptible animals. After drenching the animals were maintained worm-free during 1 month until experimental infection with 10,000 Haemonchus contortus infective larvae (L3). Enzyme-linked immunosorbent assay was carried out in serum samples to determine the level of IgG, IgA and IgE anti-H. contortus L3 crude extracts and adult excretion/secretion products (ESP). Parasitological and blood immunological parameters were measured on the 2 extreme groups. Despite the absence of any typical signs of haemonchosis, susceptible kids had more than 11 times higher faecal egg counts (FEC) at 35 days post-infection (d.p.i.) than resistant kids had. Levels of immunoglobulin against H. contortus L3 and ESP increased significantly after infection in both groups. However, no difference in the host immune response mediated by immunoglobulin against H. contortus was evidenced between groups. This finding suggests that, in goats previously infected by H. contortus, a degree of protection occurred and the phenotypic and genetic segregation in resistant and susceptible animals were not related to the humoral immune response. The correlation coefficients between FEC and IgE anti-ESP (r=0.593; P<0.05 was significant in both resistant and susceptible animals. Such correlation suggesting a hypersensitivity reaction dependent on worm prolificacy has never been described. This result needs further studies to understand the mechanisms underlying this observation.     

Eprinomectin 'pour-on' and the shedding of Haemonchus contortus eggs in experimentally infected goats

The effect of eprinomectin on goats experimentally infected with the nematode Haemonchus contortus was investigated. Faecal analysis showed that a single dose of eprinomectin 'pour-on' delayed the onset of shedding of eggs for 10 to 17 days.     

Evaluation of Cymbopogon schoenanthus essential oil in lambs experimentally infected with Haemonchus contortus

Hematophagous gastrointestinal parasites cause significant economic losses in small ruminant grazing systems. The growing reports of multi-drug resistant parasites call for intensive research on alternative treatments for anthelmintics to help small ruminants cope with these parasites. Two-month-old lambs with mean body weight (BW) of 22.5 kg were experimentally infected with a multidrug-resistant Haemonchus contortus strain. Infected animals were dosed orally with Cymbopogon schoenanthus essential oil to evaluate its anthelmintic potential. Eighteen animals were allocated into three groups of six animals, and each received one of the following treatments: Group 1 - control (10 mL of water), Group 2 - C. schoenanthus essential oil (180 mg/kg BW); and Group 3 - C. schoenanthus essential oil (360 mg/kg BW). Animals received the oil once a day for 3 consecutive days. Lambs were evaluated clinically for blood biochemistry before, at 1, 5, 10, 15 and 20 days after treatment, and then were euthanized to assess the total worm burden. No statistically significant reduction in fecal egg count, packed cell volume or total worm count was observed after treatments. Also, no statistical difference among group means for blood levels of urea, creatinine, albumin, alkaline phosphatase, aspartate aminotransferase and gamma glutamyl transferase was found. Larval development assay (LDA) and egg hatch assay (EHA) were performed from feces of treated animals at 1, 5, 10 and 15 days after essential oil administration. An inhibition in LDA was observed 1 day after the 3-day treatment in larvae from feces of animals treated with 360 mg/kg essential oil. In conclusion, the essential oil at the doses of 180 mg/kg and 360 mg/kg was safe to sheep, but failed as an anthelmintic treatment when applied to young sheep artificially infected with a multidrug-resistant H. contortus strain.     

捻转血矛线虫Hc38基因DNA疫苗对绵羊免疫保护性效果评价

为了研究基因疫苗对绵羊的免疫保护效果,本研究构建了捻转血矛线虫(H.contortus)Hc38基因DNA疫苗.将H.contortus Hc38基因保守结构域克隆到真核表达载体pcDNA3.1中,免疫鼠8d后用RT-PCR检测到该疫苗在鼠肌肉组织中进行了转录.将纯化的DNA疫苗免疫绵羊后,用western blot和ELISA方法检测疫苗在绵羊体内的翻译和诱导IgG的产生.二免后2周用10 000条H.contortus第3期幼虫攻击实验动物,检测绵羊粪便虫卵排出、成虫数量等免疫保护性指标.该H.contortus Hc38 DNA疫苗与对照组比较,免疫组绵羊排出虫卵减少66.6%、成虫减少33.1%.特别值得注意的是免疫组的静脉注射方式产生抗体最高,相应羊的虫卵数和成虫数低.本实验证明Hc38基因DNA疫苗对绵羊虫卵及成虫发育具有明显的抑制作用.     

Effect of feeding sericea lespedeza leaf meal in goats experimentally infected with Haemonchus contortus

Effect of sericea lespedeza [SL; Lespedeza cuneata (Dum-Cours.) G. Don.] leaf meal feeding was evaluated in two experiments in indoor reared goats with experimental infection of Haemonchus contortus larvae. In the first experiment, ten 8-10 month old male Spanish and Alpine cross kids pair matched for body weight and age were fed SL or bermudagrass [BG; Cynodon dactylon (L.) Pers.] hay one week before infection and were infected with 5000 H. contortus L(3). The animals were maintained on the same diet for the remaining period and were slaughtered 28 days post-infection (DPI) to determine the establishment of incoming infective larvae. Goats fed SL had lower establishment (P<0.05) of H. contortus larvae than that of the control goats fed BG hay. In the second experiment, twenty-five 8-10 months old male Alpine cross, Saanen, Nubian×Saanen and Spanish kids reared in confinement on BG were experimentally infected with 5000 H. contortus L(3). On 35 DPI, the animals were allocated to two groups after blocking by fecal egg count (FEC), and one group was fed SL leaf meal (n=13), and another control group remained on BG (n=12). Four goats/group were slaughtered successively on days 7, 14, and 28 days post SL feeding, except on day 7, when five SL fed goats were slaughtered. Fecal egg counts and blood packed cell volume (PCV) were measured at weekly intervals and worm count, female worm fecundity, worm length and mucosal eosinophils, mast cells and globule leucocytes were measured after slaughter. Goats fed SL had a lower FEC (P<0.05) one week after feeding, as compared to those fed on BG, and the values remained at low level thereafter. Similarly, PCV was also significantly affected by feeding (P<0.01), and feeding and time interaction (P<0.05). However, worm burden, female worm fecundity, parasite length, and mucosal inflammatory cell count were similar between the groups. Feeding SL reduced the establishment of infective larvae and FEC of H. contortus in experimental studies and this plant could be used for biological control of parasite infection under field conditions to limit the harmful effects of the parasites in goats.     

Changes in the body condition scores of Nigerian West African Dwarf sheep experimentally infected with mixed infections of Haemonchus contortus and Trichostrongylus colubriformis

Weekly changes in body condition scores and body weights were determined in West African Dwarf sheep following trickle exposure to weekly escalating mixed infections with Haemonchus contortus and Trichostrongylus colubriformis starting with single doses of 500 infective larvae (L(3)) at wk1, 1000 L(3) at wk2, 2000 L(3) at wk3 and 4000 L(3) at wk4. Thirty-three animals were randomly assigned to two groups namely, Group 1 (n=27) and Group 2 (n=6). Group 1 animals were used for experimental infections and Group 2 animals served as uninfected controls. Body condition scores (BCS), body weights (BW), faecal egg counts (FEC) per gram of faeces and worm burden (Wb) were determined using standard procedures. Lambs in group 1 with epg ≤ 1000 were classified as strong responders (n=16), those with epg between 1000 and 10,000 as intermediate (n=5) and lambs with epg>10,000 on any sampling day were classified as weak responders (n=6). Based on this classification, the mean epg of lambs classified as strong responders was significantly lower (P<0.001) than the epg of lambs classified as weak responders. The body condition scores and body weights of the strong responder lambs were comparable with those of the uninfected control and they were significantly higher than those of the weak and intermediate responders from wk5 till the end of the experiment. There was an inverse and significant relationship between the average BCS of days 56 and 59 and the average FEC of days 56 and 59 (r(s)=-572; P=0.017; n=27) as well as with Wb (r(s)=-531; P=0.028; n=27). We concluded that changes in the body scores are good indicators of the intensity of gastrointestinal nematode infection in the Nigerian WAD sheep.     

SHORT COMMUNICATION: Neutrophil oxidative metabolism and haemogram of sheep experimentally infected with Haemonchus contortus and supplemented with selenium and vitamin E

The objective of this study was to evaluate neutrophil oxidative metabolism and haemogram in sheep experimentally infected with Haemonchus contortus and supplemented with selenium and vitamin E. Twenty male Corriedale sheep were utilised and distributed into four experimental groups each with five animals infected with larvae: G1‐ supplemented with sodium selenite, 0.2 mg/kg body weight (bw) given intramuscularly (IM); G2‐ supplemented with sodium selenite and vitamin E, 0.2 mg/kg bw and 2000 IU per animal, respectively, both IM; G3‐ supplemented with vitamin E, 2000 IU per animal IM; G4‐ not supplemented. A haemogram and the number of parasite eggs were determined in samples of blood and faeces, respectively, on days zero (T0), 20 (T1), 40 (T2) and 60 (T3) and nitroblue tetrazolium (NBT) assays were performed on heparinized blood samples taken on days zero, 30 and 60. A lower total leucocyte count was detected in G1 in relation to G4 at T4. Lymphocytes were reduced in G1 in relation to G3 and G4 at T3. In both non‐stimulated (NBT‐NS) and stimulated (NBT‐S) dye reduction assays, there was reduced activity at 60 days, in relation to other times in the groups treated with selenium (G1 and G2). On the basis of results obtained, we conclude that supplementation with selenium provides better antioxidant protection to neutrophils.     

The distribution of pepsinogen within the abomasa of cattle and sheep infected with Ostertagia spp. and sheep infected with Haemonchus contortus.

The effect of nematode infections on the production of pepsinogen by ruminants was investigated immunohistochemically and biochemically. Abomasal tissues were collected from parasite-naive cattle and sheep, from sheep infected with predominantly Ostertagia circumcincta, sheep infected experimentally with Haemonchus contortus and cattle infected with Ostertagia ostertagi. Pepsinogen was also assayed biochemically in homogenates of fundic mucosae from sheep infected with predominantly O. circumcincta. Infection with Ostertagia spp. parasites was associated mainly with nodular hyperplasia, resulting in increased numbers of cells that produce both pepsinogen and mucus. Measured biochemically, nodules contained more pepsinogen than adjacent more normal mucosa (p < 0.05), and this effect was largely attributable to the greater mass of nodules. Infection of sheep with H. contortus was associated with generalised hyperplasia, characterised by increased numbers of mucopeptic cells and in at least one animal with reductions in parietal cell numbers. At the same time, the zymogen granule content of chief cells was reduced. Similar changes were occasionally seen in sheep infected predominantly with O. circumcincta. Generalised hyperplasia is likely to be indicative of the presence of ambulatory parasitic stages as opposed to those confined to nodules. The potential for the enhanced production of pepsinogen by increased numbers of cells with a joint mucous cell and zymogenic cell phenotype may offset decreases in the numbers of chief cells or reductions in chief cell activity.     

Pathological and immunohistochemical study of the abomasum and abomasal lymph nodes in goats experimentally infected with Haemonchus contortus

Histopathological changes and the distributions of T and B lymphocytes and IgG producing plasma cells were recorded in the abomasum and abomasal lymph nodes of goats 3, 7 and 21 weeks post-infection (wpi) after an experimental infection with H. contortus. The low rate of worm recovery by 3 wpi (5.6%) might have been due to larvae death as suggested by the presence of granulomas in the abomasal mucosa at 3 and 7 wpi, or simply due to a poor larval establishment. Marked increase in the secretion of mucus by mucous cells together with an abundant infiltration of eosinophils, mast cells, CD3+ T lymphocytes, CD79a+ B cells, IgG+ plasma cells and globule leukocytes were recorded in the abomasal mucosa, especially at 7 wpi. Except for the globule leukocytes, this reaction decreased substantially by week 21, suggesting this cell type may have been involved in rejection of adult nematodes. The abomasal lymph nodes showed marked hyperplasia, particularly of CD79a+ B cells and IgG+ plasma cells in all infected goats. These reactions may have been responsible for the reduction in the number of worms found in the abomasum between 3 and 7 wpi.     

捻转血矛线虫免疫调节型DNA疫苗的构建及在山羊体内表达研究

为构建免疫调节型DNA疫苗,将山羊IL-2基因分别与捻转血矛线虫H11-1、H11-2和H11-3基因串联构建融合表达载体pcDNA/IL-2-H11-1、pcDNA/IL-2-H11-2和pcDNA/IL-2-H11-3。为检测疫苗在山羊体内的表达情况,将纯化的疫苗质粒肌肉注射山羊后取注射部位肌肉组织,于首次免疫7 d后和二次免疫10 d后分别用RT-PCR和Western Blot等方法检测H11抗原的转录和翻译情况。结果发现H11基因和IL-2基因均能在注射部位肌肉获得转录和翻译。     

山羊源3种不同形态阴门盖捻转血矛线虫雌虫的多位点序列分析

旨在解析3种不同形态阴门盖捻转血矛线虫（Haemonchus contortus）的遗传进化差异,本研究从养殖场山羊皱胃中分离到捻转血矛线虫虫体,采用普通光学显微镜观察71条雌虫虫体阴门盖的形态结构特征,并基于捻转血矛线虫ITS-1、ITS-2和nad4基因位点,采用PCR法对不同阴门盖的虫体进行扩增,通过比对多位点序列进行遗传进化分析。经显微镜观察发现,本研究分离到的捻转血矛线虫雌虫阴门盖存在舌瓣形、亚球形和舌-球混合形3种形态,所占比例分别为45.07%（32/71）、50.70%（36/71）和4.23%（3/71）。对43条雌虫全长和阴门至虫体末端长度进行测量和统计分析,结果显示,3种不同形态阴门盖的捻转血矛线虫全长统计学差异不显著（P>0.05）,而3种不同形态阴门盖的捻转血矛线虫阴门至虫体末端的长度存在显著性差异（P<0.05）。基于捻转血矛线虫ITS-1、ITS-2和nad4基因进行的序列分析结果显示,不同形态阴门盖虫体的9个样品在3个基因位点上存在不同程度的碱基差异,多态性位点分别为10、13和43个,核苷酸多态性分别为0.85%、1.34%和1.97%。基于ITS-1和ITS-2构建的遗传进化树显示,研究中所用样品与GenBank上H.contortus的参考序列处于同一进化支,表明本研究所分离到的虫体均属捻转血矛线虫。捻转血矛线虫雌虫的阴门盖存在形态学差异,不同形态阴门盖虫体在ITS-1、ITS-2和nad4基因位点上均存在不同程度的碱基差异,此研究结果为捻转血矛线虫的种类鉴定和遗传进化提供了参考数据。     

Haemonchus contortus with low inhibited development in sheep from the highveld of Zimbabwe

The abomasa of sheep grazing on natural pastures in the highveld of Zimbabwe were examined for Haemonchus contortus. Of 304 abomasa, 213 (70%) harboured H. contortus. The worm burden increased during the rains to reach the peak in February-March. This was followed by a decline with low worm loads throughout the dry season. The fourth stage larvae (L4) accounted for 1-7% of the total H. contortus population, except during July and August when they comprised 22 and 54% of the worm burden, respectively. It appears that the inhibition of H. contortus is not common in the commercial farming sector where sheep are treated very frequently.     

The predatory capability of Arthrobotrys cladodes var. macroides in the control of Haemonchus contortus infective larvae

One hundred compost samples were examined for the presence of nematophagous fungi on the sheep farms of Mazanderan, province, Iran. Arthrobotrys cladodes var. macroides (IRAN 677C = CBS 143565) was isolated from 3% of the samples examined. Nematophagous activity of this fungus which was shown for the first time in this study, revealed the addition of 1000, 8000, 20 000 and 100 000 conidia per gram of feces of sheep reduced significantly (P < 0.001) the number of Haemonchus contortus infective larvae in the feces by 41.71%, 63, 27%, 73.49% and 94.96%, respectively. These results show that A. cladodes var. macroides is a promising candidate for biological control of H. contortus.     

不同粪便处理模式对羊粪中捻转血矛线虫虫卵杀灭效果的影响

为了评价不同粪便处理模式下羊粪中捻转血矛线虫虫卵的杀灭状况,2018年8月至10月,对福州市某羊场的羊粪,分别采用堆积发酵(Ⅰ组)、塑料罐密闭储存(Ⅱ组)、舍内自然放置(Ⅲ组)等3种方式进行处理。第Ⅰ组堆积发酵30 d后可完全杀灭粪中虫卵;第Ⅱ组密闭储存20 d后可完全杀灭虫卵;第Ⅲ组自然放置50 d可杀灭虫卵97.9%。试验结果可为羊场的粪便处理提供参考依据。     

Inheritance of fecal egg count and packed cell volume and their relationship with production traits in sheep infected with Haemonchus contortus

This study describes responses to artificial infection with Haemonchus contortus in ewes and lambs of 50% Dorset, 25% Rambouillet, and 25% Finn-sheep ancestry and provides estimates of genetic parameters for measures of parasite resistance. One hundred ninety-eight ewes out of 64 sires, and 386 lambs out of 25 sires were evaluated in autumn and spring of 2 yr. Ewes were dewormed shortly after weaning their lambs and lambs were dewormed at about 120 d of age. One week after deworming, ewes and lambs were dosed with approximately 10,000 infective larvae of H. contortus. After infection, BW, fecal egg counts (FEC), and packed cell volume (PCV) were measured weekly for 7 wk in lambs kept in drylot and fortnightly for 11 wk in ewes on pasture. Summary traits were defined as initial PCV, mean BW across all times, and means for PCV (MPCV) and log-transformed FEC (MLFEC) at wk 3 to 7 after infection for lambs and wk 3 to 11 after infection for ewes. Ewes and lambs did not lose weight overall in any year or season, but there was no consistent effect of year or lambing season on mean LFEC or mean PCV during infection in either ewes or lambs. Yearling ewes were less resistant to infection than older ewes, with lower PCV (P < 0.05) and higher LFEC (P < 0.05). During infection, PCV was positively correlated with BW and negatively correlated with LFEC in both ewes and lambs. In lambs, heritabilities were 0.39 (P < 0.01) for PCV, 0.10 (P < 0.05) for LFEC across all measurement times, and 0.19 (P < 0.01) for three measures of LFEC taken at the peak of infection. Heritability estimates for ewes were 0.15 (P < 0.05) for PCV and 0.31 (P < 0.01) for LFEC. Repeatabilities for LFEC and PCV across measurement times were moderate in ewes and lambs. Correlations between dam and lamb records for MLFEC were generally low, suggesting different mechanisms of resistance in lambs and nonlactating ewes. Ewes with higher genetic merit for growth as lambs were less resistant to infection as adults, but genetic merit for fertility and prolificacy were not related to parasite resistance. Lambs with higher genetic merit for body weight were more resistant to infection. Selection for resistance to H. contortus is therefore possible and should not adversely affect growth of lambs and fertility of ewes in this production environment.     

Efficacy of mebendazole in sheep experimentally invaded with larvae of Haemonchus contortus and Trichostrongylus colubriformis in relation to the results of clinical examination]

A group of six lambs at the age of two months and of the average weight of 13 kg were invaded with the larvae Haemonchus contortus and Trichostrongylus colubriformis; the course of invasion was compared with that in a group of four control lambs. In regular ten-day intervals, some hematological indices, proteinemia. SGOT and SGPT activities, glucose level, sodium and potassium were studied in blood samples; at the same time egg elimination was observed in excrement samples. The invasion intensity was checked by helminthological dissection of an experimentally invaded lamb 35th day p.i.; 576 H. contortus adults and 398 T. colubriformis adults were determined. Egg number recalculated per 1 g excrements (E.P.G.) amounted to 3072. At that stage, both groups were administered mebendazole at a dose of 10 mg active substance per 1 kg live weight on three successive days. The efficacy of the treatment (IE) was 97.01 to 98.05%. According to the clinical examination the hematocrit level dropped statistically significantly on the ninth day p.i., the other indices under study showed no changes. The drug administration increased temporarily the erythrocyte count and decreased MCV and MCH. Although mebendazole mainly inhibited glucose metabolism in the nematodes, the drug administration did not influence the glucose level of the host's blood serum.     

Localization of immunoglobulin-containing cells in the abomasum of sheep following infection with Haemonchus contortus.

Abomasal cannulation followed by serial collection of biopsies was used to study the kinetics of appearance of IgA-, IgG1-, IgG2- and IgM-containing cells in the abomasum of sheep following infection with Haemonchus contortus. Very few immunoglobulin-containing cells (ICC) were found in the abomasum of sheep before infection. Following H. contortus infection, there were increased numbers of ICC in the submucosa of the abomasum. Seven days after infection, the numbers of IgA-, IgG1- and IgM-containing cells were six times greater than for uninfected control animals. The numbers of ICC continued to rise as the infection progressed, and the peak response was observed between 21 and 28 days after infection. IgA-containing cells (68-84%) were the most frequent cell types at all the observation times, followed by IgG1 and IgM. IgG2-containing cells were minimal throughout the experiment. As there were no significant changes in the numbers of ICC in the abomasum of uninfected controls it is concluded that H. contortus stimulated a local immune response in the abomasum of parasitized sheep.     

Effect of dimethyl sulfoxide in the treatment of sheep experimentally infected with Ehrlichia ruminantium

OBJECTIVE: To evaluate the clinical response of sheep experimentally infected with Ehrlichia ruminantium to treatment with dimethyl sulfoxide (DMSO). ANIMALS: 32 Merino crossbred sheep. PROCEDURES: 16 sheep were infected with E ruminantium; 8 of these were treated twice daily with a 10% solution of DMSO (1 g/kg, i.v.) in polyionic fluid for 3 consecutive days. Treatment was initiated 2 days after the onset of clinical disease. Eight uninfected control sheep were similarly treated with DMSO. Placebo treatments (polyionic fluid administrations) were given to 8 infected and 8 uninfected sheep. Arterial and venous blood samples for blood gas and total plasma protein concentration measurements were collected daily (data from 5 days before until 6 days after onset of clinical disease were analyzed); physiologic variables and food consumption were also monitored. Gross pathologic findings and cytologic confirmation of the disease were recorded for the 16 infected sheep. RESULTS: Infected sheep treated with DMSO were able to maintain pulmonary gas exchange and had reduced pleural effusion and plasma protein loss, compared with infected untreated sheep that became hypoxic. Infected treated sheep developed an uncompensated metabolic acidosis. Uninfected treated sheep had reduced appetite, whereas uninfected untreated sheep maintained normal food intake. CONCLUSIONS AND CLINICAL RELEVANCE: Results of DMSO treatment in sheep with experimentally induced heartwater disease indicated that administration of this agent, in combination with specific antimicrobial treatment, may be of some benefit in treatment of naturally occurring disease.