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The anthelmintic efficacy of resorantel against Thysaniezia giardi and Avitellina spp. was tested in sheep at a dosage rate of 65 mg kg-1 live mass. The reduction obtained was 100% in at least 80% of the treated flock.
The growth, using freshly cultured Escherichia coli with ampicillin or heat-treated lyophilised E coli as a food source, of the larvae of the mouse nematode Nematospiroides dubius and the infectivity of resulting third stage larvae were determined. Concentrations of E coli between 0.5 and 1 mg dry weight ml-1 permitted optimal larval development for both N dubius and Trichostrongylus colubriformis. Development of larvae of susceptible and cambendazole-resistant strains of Haemonchus contortus in thiabendazole solutions showed clear differences between the strains and the larval development test was more sensitive than the egg hatch test. The test also detected a levamisole resistant strain of H contortus, although the degree of resistance could not be adequately measured. It is concluded that the test can be run with any anthelmintic to which resistance is suspected.
The new compounds CGP 6140 and CGP 20376 were tested for their anthelmintic activity against adult Paragonimus uterobilateralis in experimentally infected Sigmodon hispidus. Both drugs were effective at a dosage of 2 x 100 mg/kg b.w. given orally with an interval of six hours between the doses. This regimen killed 80% of the flukes collected on Days 7 and 11 after treatment with CGP 6140 and 100% of the flukes collected on Days 5, 7, and 11 after therapy with CGP 20376. Both compounds showed no effect at single doses of 25, 50 and 100 mg/kg or with 12.5 and 25 mg/kg/day given on four consecutive days.
Groups of very similar sheep (breed, sex, age, hemoglobin type, family) were immunised against H. contortus by repeated infections. Self-cure and immune reactions expelled parasites but some of them still remain in the gut of animals; they have been eliminated by dosage of anthelmintics. Animal were challenged; a discrepancy exists between numbers of eggs passed in each group (immune and dosed animals, immune and non-dosed animals and non-immune animals); the best fitting estimated equation on experimental values (or on moving average points) is used for statistical tests. Immunity vanishes partly (or totally) when animals have been dosed; a residual population of worms is thought to be responsible for immunity because of a permanent booster.
Toxicity and interaction of topical application of dichlorvoscrotoxyphos (D-C) insecticide and phenothiazine anthelmintic (PTZ) given in the diet were studied in 4 groups of 4-5 lambs each that had had prior drug exposure. In a study reported previously each lamb in groups 1 and 2 was sprayed with 3 biweekly topical applications of 1550 ml of 0.25% D-C emulsion. Groups 1 and 3 were treated with PTZ (12.5 g/sheep initially and 4 days later with 6.25 g every 3 days for 9 treatments). Group 4 was the control. Following termination of that study the animals were given a 30-day nonmedicated period and reused in the present study as described below. Each lamb in group 1 and 3 was challenged with PTZ given in the diet (1g/sheep/day for 3 days). On the third day of PTZ administration, each lamb in group 1 and 2 was sprayed with 1 gallon of 0.25% D-C emulsion. The 4th group served as a control. Following D-C spray, clinical signs of toxicosis were seen within 17 min in 56% of the exposed lambs regardless of concurrent PTZ treatment. The erythrocyte acetylcholinesterase (EACE) activities of the D-C exposed groups were significantly (P less than 0.05) depressed on post-treatment days (PTD) 1 and 3 regardless of the PTZ treatment. The base-line EACE values were reestablished on PTD 18. The PTZ alone was not toxic and did not inhibit EACE activity.(ABSTRACT TRUNCATED AT 250 WORDS)
When the anthelmintic Banminth 'Katze' was administered twice to ninety-two cats, the owners were questioned on the method by which the animals took this paste. Minor, if any, problems were observed in 94.5 per cent of the cats. Major problems occurred in 5.5 per cent of the animals. Significantly more adult than young cats had difficulties in taking the paste.
The anthelmintic efficacy of albendazole (methyl [5-(propylthio) - 1H - benzimidazole -2 -yl] carbamate) against immature and adult Fasciola hepatica and against standardised strains of benzimidazole resistant Haemonchus contortus and Trichostrongylus colubriformis was evaluated in experimentally infected sheep. A single intrarumenal treatment of dose rates of 3.8 and 7.6 mg/kg was ineffective against immature (six weeks old) F hepatica. Dose rates of 5.7 and 7.6 mg/kg reduced the number of mature (12 weeks old) F hepatica by 70 and 91 per cent respectively. Dose rates of 5.7 and 7.6 mg/kg removed 92 and 99 per cent of four-week-old, benzimidazole resistant H contortus and 89 and 99 per cent of four-week-old, benzimidazole resistant T colubriformis.
In mice, the electroconvulsant threshold was elevated after oral administration of 7 benzimidazole anthelmintics at a dose of 100 mg/kg. This effect was most pronounced with cambendazole which also showed an outstanding duration of action. None of the drugs tested elevated the pentetrazole seizure threshold.
Anthelmintic activities of the B1a fraction of avermectin were evaluated in a controlled experiment. Twenty 12-week-old calves artificially infected with gastrointestinal nematodes were allotted to four groups. Calves in group 1 were used as nonmedicated controls; other calves in groups 2, 3, and 4 were given (orally) B1a avermectin at dosage levels of 50, 100, and 200 microgram/kg of body weight, respectively. These treatments were given 35 days after calves were inoculated with infective nematode larvae. In groups 2, 3, and 4, overall reductions (based on geometric means) were 98.6%, 98.7%, and 98.4%, respectively. These reductions were highly significantly different (P less than 0.01) from the control calves. Nematodes in the calves were Haemonchus contortus. Ostertagia ostertagi, Trichostrongylus axei, T colubriformis, Cooperia oncophora, C punctata, and Oesophagostomum radiatum.
Anthelmintic trials were carried out to evaluate the efficacy of albendazole against helmi of 2,5 to 3,8 mg/kg administered orally, resulted in a 98,8 to 100% reduction of adult parasites of the genera Haemonchus, Ostertagia, Trichostrongylus, Nematodirus, Gaigeria, Oesophagostomum, Chabertia, Marshallagia and Cooperia. Against the immature stages of these genera, except for Marshallagia and Cooperia, which were not tested, a dose level of 2,5 to 3,8 mg/kg was 83,9-100% effective. Albendazole at 2,5 mg/kg was 99,0% effective against adult stages of Dictyocaulus; its activity at a dose of 3,8 mg/kg against the immature stages of D. filaria was 89,3%. In sheep naturally infested with Moniezia, 100% elimination was obtained at a dose level of 2,5 mg/kg. Dose levels of 3,8 mg/kg and higher were more than 76% effective against adult Fasciola hepatica, while a dose of 4,8 mg/kg was 63% effective against adult Fasciola gigantica.
In an experimental patent infection of Ancylostoma ceylanicum in golden hamsters the efficacy of seven anthelmintics was tested; bephenium hydroxynaphthoate, tetramisole, tetrachlorethylene, phenylene 1,4-diisothiocyanate, thiabendazole, parbendazole and mebendazole were studied. Mebendazole was the most effective, with parbendazole, phenylene 1,4-diisothiocyanate, thiabendazole and bephenium hydroxynaphthoate also satisfactory. Tetrachlorethylene and tetramisole were the least effective in our screen.
In vitro and in vivo experiments were employed in the screening of potential anthelmintic agents against Opisthorchis viverrini infection in hamsters. A few selected groups of compounds tested included those that are commercially available as well as those that are still being tested by various pharmaceutical firms. The compounds tested in the present study were praziquantel, amoscanate, albendazole, flubendazole, metrifonate, metronidazole and benzodiazepine derivatives. Results from both in vitro and in vivo experiments showed that at the dosages employed, praziquantel was the only one that gave complete cure, as judged from faecal egg examination and worm recovery at the time of sacrifice. It was therapeutically effective against different developmental stages of O. viverrini including the metacercariae. Moreover, the drug was also effective as a chemoprophylactic agent when given 6 to 12 hr prior to being exposed to infective metacercariae. Other compounds tested were considerably less active although some might have permanently damaged the fluke reproductive capacity, while others were able to suppress egg-laying capacity only temporarily. Together, results suggests that the ineffectiveness of most agents tested in this study is not related to their inability to attain concentrations high enough to kill or damage the flukes in the biliary system but is most likely due the inherent lack of capacity to kill the flukes.
The development of immunity against Ancylostoma caninum larval reinfection has been investigated in mice after the primary infection has been treated with an effective anthelmintics. Experimentally A, caninum larvae infected mice treated with levamisole (5 x 40 mg/kg), thiabendazole (5 x 200 mg/kg), oxfendazole (5 x 100 mg/kg), or albendazole (5 x 100 mg/kg) when challenged with A. caninum larvae showed 47.77 to 55.81% larval reduction from the challenge dose indicating thereby the development of partial immunity.
A number of 1,4-di-(3,4-disubstituted benzoyl)piperazines (3-6), 1-(3,4-disubstituted benzoyl)-4-(3,4-disubstituted phenyl)piperazines (9-11), 1,4-di-(2-carbalkoxyaminobenzimidazol-5(6)-yl-carbonyl)piperazines (12, 13), 1-(2-carbalkoxyaminobenzimidazol-5(6)- ylcarbonyl)-4-(2-carbalkoxyaminobenzimidazol-5(6)-yl) piperazines (14, 15) and 1-(2-carbalkoxyaminobenzimidazol-5(6)-yl)-4-(N,N- dicarbalkoxyamidino)piperazines (17, 18) have been synthesized and their anthelmintic activity is reported.
The effects of six anthelmintics on larval stages of Nematospiroides dubius in mice were assessed. Levamisole phosphate, at a dose of 100 mg/kg administered per os 6 days postlarval inoculation (PI), effected greater than 98% reduction in worm burdens. At dose rates one log2 higher, 50% mortality of the mice occurred. Ivermectin, given per os at a dose rate of 5 mg/kg, removed all of the worms when administered either on Day 3 or 6 PI. No toxicity was observed even at the highest dose tested (25 mg/kg). Albendazole, cambendazole, pyrantel pamoate, and fenbendazole, all given per os at a dose of 100 mg/kg on day 6 PI, allowed from 52 to 75% of the worms to develop to adulthood. Ivermectin emerged as the larvicidal drug of choice owing to its high efficacy and undetectable toxic side effects.
The anthelmintic efficacy of ivermectin administered by subcutaneous (SC) injection or orally via the drinking water was investigated in feeder pigs naturally infected with Ascaris suum and Trichuris suis. Group 1 pigs (n = 5) were given drinking water as a placebo, group 2 pigs (n = 5) were given ivermectin by SC injection (300 micrograms/kg of body weight), and group 3 pigs (n = 5) were given ivermectin in water also at a dosage rate of 300 micrograms/kg of body weight. At necropsy 11 days later, the mean worm counts in group 1 pigs were 4 for Ascaris and 50.2 for Trichuris. All adult and juvenile ascarids were removed from the intestine in groups 2 and 3 pigs. Compared with the number of Trichuris in group 1 pigs, the number of Trichuris was reduced by 91.2% and 78.1%, respectively, for the orally and SC treated pigs.
The persistent anthelmintic effect of ivermectin given subcutaneously at 200 mcg/kg was evaluated against induced infections of Haemonchus placei, Ostertagia ostertagi, Cooperia spp. (C. pectinata and C. punctata), Bunostomum phlebotomum and Oesophagostomum radiatum in cattle. Forty-four Friesian bull calves raised under worm-free conditions were restrictively randomized to one untreated control group and 3 ivermectin treated groups of equal size according to mass. Animals in the different treated groups were treated either 9, 7 or 5 d before infestation, which was induced in all animals on the same day. The results are presented as percentage reduction and Non Parametric claims. Nine days after treatment the effect of ivermectin was virtually undiminished against O. ostertagi and B. phlebotomum and 7 d after treatment against Cooperia spp. Counts of all worms were reduced by 99% or more following the treatment given 5 d before infection. According to the Non Parametric Method, "A" claims (i.e. 80% effective in 80% of the treated animals) were achieved against all 5 worms up to 7 d after treatment and against O. ostertagi and B. phlebotomum up to 9 d after treatment.
Anthelmintic activities of 22,23-dihydroavermectin B1 (comprised to greater than or equal to 95% 22,23-dihydroavermectin B1a and less than or equal to 5% 22,23-dihydroavermectin B1b) against gastrointestinal nematodes in calves were evaluated in 2 controlled experiments. Infective larvae of Haemonchus contortus, Ostertagia ostertagi, Trichostrongylus axei, T colubriformis, Cooperia oncophora, and C punctate were given to 11-week-old calves and Oesophagostomum radiatum had been given 21 days earlier to allow all larvae to attain adulthood at the same time. Each experiment had 4 groups of 5 calves each. Treatment was given to the calves at 14 weeks of age, and 7 to 8 days after treatment, the calves were necropsied. In experiment 1, group 1 control calves had a geometric mean of 11,054 nematodes; groups 2, 3, and 4 calves (at 14 weeks of age) given 22,23-dihydroavermectin B1 orally at doses of 50, 100, or 200 microgram/kg had reductions of 73.5%, 97.3%, and 99.7%, respectively. In experiment 2, group 5 control calves had a geometric mean of 18,897 nematodes; groups 6, 7, and 8 calves given 22,23-dihydroavermectin B1 subcutaneously at doses of 50, 100, or 200 microgram/kg had reductions of 74.6%, 95.3%, and 98.8%, respectively.