Closantel缓释剂驱除山羊实验感染肝片吸虫的效果

选用 5只实验感染肝片吸虫山羊进行 Closantel(氯氰碘柳胺 )缓释剂驱虫试验。试验用山羊每只一次性口服肝片吸虫囊蚴 15 0个 ,感染后第 15周随机将山羊分成对照组 (n=2 )和驱虫组 (n=3) ,驱虫组每只羊口服 2丸 Closantel缓释剂 (含 15 .5 % Closantel,每丸 7.6 g) ,每周定时采集颈静脉血和进行粪便检查 ,每月称重 ,试验结束时剖检测量肝重和计数肝内虫体数 ,以驱虫前后山羊的红细胞、白细胞、嗜酸性粒细胞、血清抗体和一氧化氮的变化、体重变化、剖检时肝重 /体重之比、虫卵的变化以及虫体减少率作为衡量驱虫效果的指标。结果表明 ,投药后嗜酸性粒细胞在第 1、2、3周与对照组相比有显著下降 ,其他各项指标与对照组相比虽有一定差异但不显著。虫体减少率为 4 1.2 2 %。提示Closantel缓释剂对驱除实验感染肝片吸虫有一定效果 ,在虫体感染前投药会起到预防作用。     

Pathogenic Effiects of the Coccidium Eimeria ninakohlyakimovae in Goats

Twenty-four coccidia-free goats were reared artificially in indoor cages and allocated to 6 groups of 4 animals each. At 20 days of age, goats in groups 1–3 received 10⁴,10⁵ and 10⁶ sporulated oocysts of Eimeria ninakohlyakimovae per goat, respectively, each as a single dose. Goats in group 4 received daily doses increasing over a 3-week period, starting with 100/day for the first week, followed by 1000, and 10 000/day in weeks 2, 3, respectively. Goats in group 5 received 10⁴ oocysts following a challenge dose of 10⁶ oocysts on day 32. Goats in group 6 were kept as uninoculated controls. Infected animals showed diarrhoea and weight loss. Goats in group 4 showed longer periods of diarrhoea and patency than other infected goats. Goats in group 5 showed the same severe clinical signs as those in group 3 but produced very low oocyst output after a challenge dose. The diarrhoea was associated with a reduction in alkaline phosphatase activity and increases in packed cell volume and haemoglobin. No significant differences were found in serum aspartate aminotransferase, alanine aminotransferase, total protein, albumin, globulin, Na⁺, K⁺,Cl⁻ between groups during 48 days after inoculation. There were no serum enzyme indications of damage to the liver. Histological examination performed 100 days after inoculation revealed that inoculated goats had mild subacute to chronic proliferative enteritis in the lower small intestine and the large intestine, and the mesenteric lymph nodes, gallbladders and livers also showed slight histological lesions. The results showed that E. ninakohlyakimovae was highly pathogenic.     

Comparative efficacy of clorsulon and albendazole against Fasciola hepatica in cattle

In a dosage-confirmation trial, anthelmintic activities of clorsulon and albendazole against Fasciola hepatica were evaluated and compared. Twenty-eight cattle (8 to 12 months old) with natural F hepatica infections were randomly allotted to 4 groups of 7 cattle each: group 1, no treatment (controls); group 2, clorsulon suspension given orally at 3.5 mg/kg of body weight; group 3, clorsulon suspension given orally at 7 mg/kg; and group 4, albendazole paste given orally at 10 mg/kg. At necropsies, performed 7 and 8 days after treatment, control cattle harbored a geometric mean of 133.2 F hepatica, 16.0 of which were immature. Clorsulon administered at 3.5 mg/kg or 7 mg/kg resulted in greater than 99% removal of F hepatica, including immatures. Albendazole treatment resulted in a 76% overall reduction in F hepatica, including a 91% reduction of immatures. Fascioloides magna also were found in the cattle, but neither clorsulon nor albendazole caused significant reductions of the parasite. Adverse reactions to the 2 drugs were not observed.     

Prophylactic efficacy of clorsulon against Fasciola hepatica in calves and sheep

A daily oral 5 mg kg-1 dose of clorsulon for 28 days in calves given Fasciola hepatica cysts at 3, 5, and 7 days after initiation of treatment was highly effective in reducing worm burdens (98%) and preventing liver pathology. In similarly infected and treated sheep, clorsulon showed little effect as a prophylactic for delaying the onset of liver pathology. The size of flukes recovered from treated sheep was reduced. Although clorsulon prevented development of fascioliasis in treated calves, the host antibody response was qualitatively similar to that of untreated infected calves, but the magnitude of the response was reduced. Blood clorsulon levels in calves rose to 2.90 micrograms ml-1 within the first week of treatment then fluctuated between 2.65 and 2.90 micrograms ml-1 for the next two weeks. Clorsulon levels in sheep were 0.50-0.60 micrograms ml-1 lower than those in calf blood. The difference in bioavailability of clorsulon between sheep and calves may have contributed to differences in efficacy of the drug.     

Efficacy of clorsulon against mature, naturally acquired Fasciola hepatica infections in cattle and sheep

Clorsulon (3.5 or 7 mg/kg of body weight) was given orally to mature cows (dairy or beef) and to mature mixed-breed sheep harboring patent infections of Fasciola hepatica. Eighteen animals of each species were assigned to a control group (drug vehicle) or to 1 of 2 treatment (3.5 or 7.0 mg/kg) groups of 6 animals each. On posttreatment days 8 (cows) or 14 (sheep), the animals were slaughtered for recovery of flukes. In cows, the efficacy (P values for treatment groups vs control) of clorsulon against infections of mature F hepatica was 99.21% (P less than or equal to 0.0065) at 3.5 mg/kg and was 100% (P less than or equal to 0.0039) at 7 mg/kg. In sheep, the efficacy was 93.33% (P less than or equal to 0.0104) at 3.5 mg/kg and was 100% (P less than or equal to 0.0039) at 7 mg/kg. These results indicate that clorsulon is a highly effective compound for the treatment of mature F hepatica in cows and sheep.     

Efficacy of oral clorsulon in the treatment of Fasciola hepatica infections in calves

Twenty calves at each of 2 Arkansas locations were inoculated with infective Fasciola hepatica metacercariae. After 56 days, the calves at each site were randomly assigned by weight to 2 treatment groups of 10 calves/group; vehicle control or clorsulon at the rate of 7 mg/kg of body weight. All treatments were given orally as a suspension. Calves were killed 6 weeks after treatment and F hepatica counts were performed for all animals. At the 2 sites, mean levels of efficacy were 96% and 91%. Adverse reactions to clorsulon or the vehicle were not observed in the calves.     

Evaluation of clorsulon against immature Fascioloides magna in cattle and sheep

Efficacy of clorsulon was evaluated against infection with immature Fascioloides magna in 24 cattle and 12 sheep. Infections were induced by oral administration of 600 metacercariae/host. In cattle, clorsulon at dosages of 7 and 21 mg/kg of body weight was 65 and 100% effective against 8-week-old flukes, and 20 and 74% effective against 16-week-old flukes, respectively. In sheep, clorsulon at a dosage of 21 mg/kg was 92% effective against 8-week-old flukes. Significantly (P less than 0.05) more F magna were recovered from untreated sheep than from untreated cattle.     

Field trial on comparative efficacy of four fasciolicides against natural liver fluke infection in cattle

A controlled trial was conducted to evaluate the current efficacy of albendazole (ABZ), rafoxanide (RFX), triclabendazole (TRC) or clorsulon (CLS) against Fasciola hepatica in naturally infected cattle. This trial was conducted in Turkey during the spring, the time of year when liver fluke infection is endemic. Fifty crossbred cattle were selected for inclusion in the trial based on finding eggs of F. hepatica in the feces. The cattle were weighed and randomly allotted into five groups of 10 cattle and treatments were as follows: Group 1 served as non-treated control (CONT), Group 2 was treated orally with ABZ at 12 mg/kg, Group 3 was treated orally with RFX at 10 mg/kg, Group 4 received TRC orally at 12 mg/kg and Group 5 received CLS administered subcutaneously (s.c.) at 2 mg/kg. On day 0 (inclusion day), individual fecal samples were collected on days 0 (inclusion day), 7, 14, 28 and 56, after treatment. The drug efficacy was assessed as a percentage of the egg or fluke reduction and body weight gain relative to the untreated control. The results in the study showed a mean reduction of egg counts by 66.7%, 68.2%, 78% and 84.2% in Groups 2-5, respectively. In conclusion, our results indicate that CLS is a highly effective compound for the treatment of F. hepatica in cattle under these field conditions.     

The susceptibility of the goat to Fasciola hepatica infections

Mixed breed goats were infected with metacercariae of Fasciola hepatica and the resulting worm burdens were quantitated after primary and secondary exposure of the goats to the parasite. Mean length and width of the parasite recovered after all primary exposures were 1.91 +/- 0.2 cm and 0.91 +/- 0.2 cm, respectively. A mean of 71.8 +/- 5.9% of the flukes were recovered from all of the primary infections. In the secondary infections, the mean length and width of the flukes from the physically smaller population was 0.88 +/- 0.27 cm and 0.53 +/- 0.19 cm, respectively. A mean of 67 +/- 6.7% of the flukes were recovered from this secondary infection. It appears that the goat is susceptible to challenge infections with F. hepatica and that its response to this infection is much like that of sheep.     

Effect of Trypanosoma vivax infection on energy and nitrogen metabolism of west African dwarf goats

A study was conducted using 32 mature 22-kg West African Dwarf Goats to measure the effect of Trypanosoma vivax infection on energy and nitrogen metabolism. Sixteen goats were infected intravenously with 14 X 10(6) T. vivax. Sixteen control goats were sham-injected. Digestibility and metabolizability of energy and N balance were measured for each goat. Heat production and energy balances were measured per treatment group from 1 wk before infection to 6 wk after infection. Goats were fed alfalfa pellets (10% above maintenance). Treated goats had a reduced (P less than .05) packed cell volume (38 to 40% before infection vs 20 to 25% 6 wk after infection) and an increased (P less than .05) rectal temperature. Log parasitemia/ml was about 6.0 to 6.2. Parasitized goats showed increased urine creatinine excretion at wk 2 postinfection. After infection, feed intake was reduced (about 15%; P less than .05) and greater variability in intake was noted. Treated and control goats had similar N output and energy output in urine. Metabolizability of energy intake was similar at 42.7 vs 42.1% in treated vs control goats, respectively. Heat production in infected goats was increased by about 15%. Treated goats lost more weight and had a lower N balance than control goats (P less than .05). The calculated maintenance energy requirement for infected goats (464 kJ ME/kg.75) was 25% greater than for control goats (375 kJ ME/kg.75).     

Clorsulon pharmacokinetics in sheep and goats following oral and intravenous administration

Clorsulon was measured in plasma and urine of sheep and goats after administration of a single intravenous (i.v.) and after a single oral dose of 7 mg/kg. A three-compartment model with elimination occurring from the central compartment was determined to best describe the i.v. data, whereas a one-compartment model with a single exponential absorption phase best described the oral plasma data. The bioavailability of orally administered clorsulon was approximately 55% in goats and 60% in sheep. Peak plasma concentrations occurred at 14 h and 15 h after oral administration in goats and sheep, respectively. Absorption from the gastro-intestinal tract effectively prolonged the elimination of clorsulon by increasing the elimination half-life from 17 to 28 h in sheep and from 12 to 23 h in goats for the i.v. and oral routes, respectively. In both goats and sheep, approximately 50% of the i.v. dose was recovered in urine as parent drug at 48 h after administration, whereas 41% and 30% of the dose was recovered after oral administration for goats and sheep, respectively. The elimination rate constant (kel) in goats was nearly twice as large as the value determined in sheep, and the urea under the i.v. plasma curve in goats was only 63% of the value in sheep indicating that goats are more effective in their capacity to eliminate clorsulon than are sheep. These differences in drug disposition between sheep and goats may account for the reduced efficacy of clorsulon reported in goats.     

The efficacy of triclabendazole and other anthelmintics against Fasciola hepatica in controlled studies in cattle

In eight controlled tests 274 cattle were used to assess the efficacies of triclabendazole, albendazole, clorsulon, nitroxynil, oxyclozanide and rafoxanide against Fasciola hepatica. Against one-, two- and four-week-old early immature fluke the mean efficacies of triclabendazole given orally at 12 mg/kg were 88.1, 95.3 and 90.7 per cent, respectively. Clorsulon, nitroxynil and rafoxanide administered at recommended dose rates showed negligible activity against these stages of the parasite. Against six- and eight-week-old infections the mean efficacies of triclabendazole at 12 mg/kg were 87.5 per cent and 95.7 per cent, respectively. Against F hepatica aged six weeks, albendazole and oxyclozanide showed no activity and clorsulon, nitroxynil and rafoxanide had only slight to moderate activity. The efficacies of triclabendazole, clorsulon, nitroxynil and rafoxanide against 10- or 12-week-old parasites were 100, 99.0, 99.1 and 90.1 per cent, respectively. Albendazole and oxyclozanide showed poor efficacy against 12-week-old infections.     

Efficacy of concomitant early summer treatment with fenbendazole and clorsulon against Fasciola hepatica and gastrointestinal nematodes in calves in Louisiana

The efficacy, safety, and compatibility of fenbendazole (FBZ) and clorsulon (CLN) were tested after oral administration of label recommended and of higher (5x) dosage rates to calves naturally infected with gastrointestinal nematodes and Fasciola hepatica. Results for 42 calves allotted to 4 treatment groups indicated a similar efficacy against mature F hepatica by FBZ (5 mg/kg of body weight) and CLN (7 mg/kg) in a combined oral suspension, compared with CLN (7 mg/kg) alone (100 vs 99% reduction). A lesser efficacy was observed against immature flukes (88.6 and 84.9% reduction, respectively). Calves given 25 mg of FBZ/kg and 35 mg of CLN/kg had nearly complete reduction of both mature (99.6%) and immature flukes (99.1%). Fasciola egg counts were reduced by greater than 99.5% in all treated groups. Against Ostertagia ostertagi, the percentage of efficacy of the combined FBZ (5 mg/kg) and CLN (7 mg/kg) treatment was 94.3% against adults and 81.3% against inhibited larvae. Efficacy against all other nematodes was 100%, except against Cooperia spp adults (98.3%) and immature Oesaphagostomum radiatum (88.0%). At 5 x dosage rates for FBZ and CLN, percentage of removal of adults and inhibited larvae of O ostertagi was 99.3 and 99.0%, respectively, and 99 to 100% for other nematodes. Results indicate that FBZ and CLN are compatible when mixed together and administered as an oral suspension to cattle and that the efficacy is similar to that of the drugs individually. On the basis of further results, we suggest that summer treatment may be superior in preventive value for gastrointestinal nematodes and F hepatica, compared with spring treatment, because of seasonal infection dynamics of the major cattle parasites in Louisiana.     

Prevalence and risk factors for intestinal parasite infection in goats raised in Nakhon Pathom Province,Thailand

The objectives of this study were to determine the prevalence and risk factors for intestinal parasite infection in goats raised in Nakhon Pathom Province. Fecal samples from 190 goats in 12 herds were collected per rectum. Questionnaires focusing on the general information about the farm and farmers, and management practices on farms were completed. Modified McMaster counting technique was performed to detect eggs of intestinal parasites. Each egg found was classified into three groups of parasites based on its characteristics. Individual and herd prevalence were calculated. Multiple logistic regressions were performed to analyze risk factors of infection. Herd prevalence of intestinal parasite infection was 100%, while individual prevalence was 79.47%. Strongyle group was the most common intestinal parasite found in this study. Moniezia spp. (8/190) and Trichuris spp. (1/190) were also found. The average number of eggs found was 1,176 eggs per gram of feces. Risk factors for intestinal parasite infection were housing system, deworming interval, and type of goat in herd. Goats housed in groups had higher infection rates compared with goats housed individually (odds ratio (OR) = 6.34; P value = 0.009). Goats in herds in which anthelmintic drugs were administered in intervals of greater than 3 months were more likely to become infected with intestinal parasites (OR = 33.07; P value <0.001). Goats in herds that kept only dairy goats were less likely to become infected than herd that kept only meat goats or kept both dairy and meat goats (OR = 46.20 and 8.75; P value <0.001 and 0.011, respectively).     

Therapeutic potential of thiamine hydrochloride in experimental chronic lead intoxication in goats

The therapeutic potential of thiamine hydrochloride (vitamin B1) was evaluated in experimental chronic lead poisoning in goats. Eighteen goats divided into three groups were used. Goats of group A served as healthy controls while those of B1 and B2 received oral doses of 10, 15 and 20 mg lead acetate (5.43, 8.15 and 10.86 mg lead kg-1 body-weight) for 30, 30 and 31 days, respectively. At the end of the 91 days, thiamine hydrochloride was given at 20 mg kg-1 bodyweight subcutaneously for 15 days to group B2. Goats of group B1 served as lead exposed untreated controls. Significantly (P less than 0.05) higher lead concentrations were found in blood, liver, kidney and brain samples of lead exposed untreated goats than in healthy control or in lead exposed thiamine treated goats. The lead concentration, however, remained significantly (P less than 0.05) higher in all these tissues of thiamine treated goats than in healthy controls and no appreciable difference could be recorded in histopathological lesions between lead exposed untreated and thiamine treated goats.     

Studies on the prevalence and laboratory transmission of fascioliasis in animals in the Kashmir Valley

In Kashmir, 85.1% of cattle, 51.3% of sheep and 14.8% of goats were found infected with Fasciola spp. The prevalence rate varied from 66.6 to 100.0%, 25.0 to 100% and nil to 66.0% in cattle, sheep and goats respectively in different months of the year. Fasciola gigantica was the predominant species in all animal species but sheep harboured both F. gigantica and F. hepatica. The prevalence of F. hepatica infection in sheep happens to be the first report from India. Lymnaea auricularia sensu stricto supported the development of F. gigantica under laboratory conditions. The incubation temperature affected the shedding of the cercariae. Snails maintained at 25-27 degrees C started cercarial shedding as early as day 20 post-infection (PI), whereas those maintained at 10-12 degrees C commenced it from day 64 PI. One out of three experimentally infected guinea pigs aged 1 month revealed adult flukes in the liver at necropsy on day 52 PI.     

The effect of pre-exposure to Fasciola hepatica or Schistosoma mansoni on challenge infection with Fasciola hepatica

Two groups of 12 and 6 rats were inoculated with Fasciola hepatica and Schistosoma mansoni, respectively. The Schistosoma-inoculated group, as well as 6 Fasciola-inoculated rats and 6 uninfected rats were challenged 8 weeks later with F. hepatica. A control group of 6 rats was left unexposed. Eight weeks after the challenge exposure all rats were necropsied and subjected to post-mortem examination. The number of Fasciola recovered after challenge was lower in both groups of rats primarily infected with F. hepatica or S. mansoni. F. hepatica-induced pathological changes were observed in all infected rats, but were pronounced in the group which was first exposed at the time of challenge of the primarily infected groups. No Schistosoma eggs or adults were detected in Schistosoma-inoculated rats. The results demonstrated that rats primarily infected with F. hepatica acquired resistance against a challenge exposure to the homologous parasite. Also S. mansoni, even without patency, can provide partial protection against F. hepatica infection.     

Host responses during experimental infection with Fasciola gigantica or Fasciola hepatica in Merino sheep I. Comparative immunological and plasma biochemical changes during early infection

This study reports the early biochemical changes in plasma, comparative host-immune responses and parasite recovery data in Merino sheep during the first 10 weeks of infection with Fasciola gigantica and Fasciola hepatica. One group of sheep were uninfected, four groups of sheep received incremental challenge doses of F. gigantica metacercariae (50, 125, 225 and 400, respectively) and the sixth group was challenged with 250 F. hepatica metacercariae. At 10 weeks post infection (wpi), sheep challenged with F. hepatica showed the greatest fluke recovery (mean 119, range 84-166); a significantly higher biomass of parasites recovered (2.5-fold greater than the highest dose of F. gigantica); and a greater mean % parasite recovery (39.3%, range 27-55%) than any group challenged with F. gigantica. Within the groups dosed with F. gigantica a strong dose-dependent response was observed in both fluke recovery and fluke biomass with increasing dose of metacercariae. The mean % parasite recovery of F. gigantica infected groups 1-5 were 26, 23, 26 and 25%, respectively, suggesting a uniform viability of parasite establishment independent of infection dose. At 6 wpi, elevated levels of plasma GLDH were observed in the F. gigantica infected groups compared to the uninfected sheep (p<0.005) whereas the F. hepatica challenged group had four-fold higher levels of GLDH compared to the F. gigantica infected group (p<0.001). Elevated levels of GGT as an indicator of epithelial damage in the bile duct was only seen in the group challenged with F. hepatica at 10 wpi when it rose from below 100 IU/l to approximately 250 IU/l (p<0.0001) whereas no detectable increase in GGT was observed in any of the groups challenged with F. gigantica. The white blood cell response to F. hepatica infection was biphasic with the initial peak at 4 wpi and a second peak at 9 wpi, corresponding to the period of migration of juvenile fluke in the liver and the time when adult flukes are migrating into the bile duct, respectively. This biphasic response was also evident in the changes in the eosinophil counts and serum haemoglobin levels. There was a trend toward higher parasite-specific IgG2 titres in sheep infected with lower worm burdens, suggesting that higher F. gigantica or F. hepatica burdens suppress IgG2 responses. The findings of this study suggest that, in early infection in a permissive host, F. hepatica appears to be more pathogenic than F. gigantica because of its rapid increase in size and the speed of its progression through the migratory phases of its life cycle.     

Determination of the effective dose of an experimental fasciolicide in naturally and experimentally infected cattle

The aim of the present study was to determine the effective dose of an experimental fasciolicide called compound alpha or 5-chloro-2-methylthio-6-(1-napthyloxy)1H-benzimidazole in experimentally and naturally infected cattle. In the first experiment, 24 fluke-free heifers were each infected with 800 metacercariae of Fasciola hepatica and re-infected on day 45 with other 600 cysts per animal. On day 75, when the animals had 4- and 10-week-old flukes respectively, they were divided into four groups (G) of six animals each according to fluke egg counts. Groups 1-3 received compound alpha at 10, 12 and 14 mg/kg/p.o., respectively. G4 remained as an untreated control. Twenty days after treatment, the animals were sacrificed for the recovery of flukes. Efficacy was assessed as a percentage of egg or fluke reduction relative to the untreated control. In the second experiment (naturally infected cattle), 24-year-old steers positive to F. hepatica eggs were blocked into four groups of five animals each. Groups 1-3 received compound alpha at 10, 12 and 14 mg/kg/p.o., respectively. Group 4 served as a non-treated control. All procedures to determine efficacy were carried out as mentioned in the first experiment. The results in the first study showed a percentage on egg reduction of 97.3, 100 and 100 and overall fluke reduction of 94.3, 100 and 100 for Groups 1-3, respectively. In the second study, the percentage of egg reduction was of 87.5, 99.1 and 100 and overall efficacy regarding fluke reduction was of 84.2, 99.6, and 100 for Groups 1-3, respectively. It is concluded that the effective dose selected for compound alpha was of 12 mg/kg/p.o. in cattle having an induced or natural F. hepatica infection.     

Pharmacokinetics and efficacy of triclabendazole in goats with induced fascioliasis

The pharmacokinetics of triclabendazole were evaluated in normal goats and in goats artificially infected with Fasciola hepatica. Triclabendazole and its metabolites were determined using a novel high performance liquid chromatographic method with fluorimetric detection after solid-phase extraction. In normal goats triclabendazole given orally was metabolized rapidly to its sulphoxide and sulphone derivatives. The maximum plasma concentrations for the sulphoxide and sulphone were similar ranging from 9 to 19 micrograms/ml and these were attained at an average 12.8 and 25.6 h, respectively, after administration. Both metabolites were eliminated slowly from plasma with elimination half-lives of 22.4 h for the sulphoxide and 19.4 h for the sulphone. They persisted at measurable concentrations in plasma for up to seven days. In milk, the two metabolites occurred in low concentrations and none of them was detectable (sulphoxide less than 0.04 microgram/ml, sulphone less than 0.02 microgram/ml) after seven days. The pharmacokinetic behaviour of triclabendazole was not altered in animals with fascioliasis. Efficacy of the drug against immature (six-week) F. hepatica was 100%.