Continuous feed medication with nitroscanate for the removal of Hymenolepis nana in naturally infected mice and rats.

In this study, the effects of nitroscanate were investigated in naturally acquired Hymenolepis nana infections in rats and mice. The natural infection was determined by centrifugal flotation technique of faeces. The infected rats and mice were divided into two treatment and two control groups (N = 10). Nitroscanate at the dose of 50 mg/kg per day was given in the diet for 4 days. The rats and mice of treatment groups were necropsied on 7th day after the last treatment together with those of control groups. Following necrospsy, in the treatment group a geometric mean of 1.07 Hymenolepis nana were recovered out of ten mice, compared with 8.14 in the control group. In the rat treatment group no Hymenolepis nana were found in ten rats, while the control group showed a geometric mean of 6.23. Nitroscanate was found to be effective 100% and 86.8% at the treatment of H. nana infection in rats and mice respectively.     

Efficacy of levamisole pour-on compared with levamisole subcutaneous injection against Dictyocaulus viviparus infection in calves.

The efficacy of levamisole pour-on against Dictyocaulus viviparus was compared to that of subcutaneous levamisole injection. Eighteen calves were raised individually and artifically infected with D. viviparus larvae. Faecal samples were collected 27 and 28 days later and larvae per gram (l.p.g.) determined. The animals were then divided into three comparable groups. Group 1 animals remained untreated as controls. Group 2 animals received levamisole 10% w/v subcutaneous injection at a dose of 5 mg kg-1 and Group 3 received levamisole pour-on 20% w/v at a rate of 10 mg kg-1 applied transdermally. Results of l.p.g. measurements from faecal samples taken 7 and 8 days post-treatment indicated a dramatic reduction in the worm burden of animals in both treatment groups. Necropsies at 14 days post-treatment revealed few adult worms in these groups, indicating a 99 and 98% kill rate for pouron and subcutaneous injection, respectively.     

Evaluation of a beef-based chewable formulation of pyrantel pamoate against induced and natural infections of hookworms and ascarids in dogs.

Pyrantel pamoate, formulated in a beef-based chewable tablet, was evaluated for efficacy in dogs against induced and natural infections of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Uncinaria stenocephala. Dose titration trials were conducted in Canada, the UK and Germany in dogs treated with pyrantel (as pamoate salt) at 0, 2.5, 5 or 10 mg kg-1 body weight. These studies showed that a dose rate of 2.5 mg kg-1, the efficacy of pyrantel against adult T. canis, T. leonina, U. stenocephala and A. caninum was 76.1, 85.6, 100 and 87.9%, respectively. Efficacy at 5 mg kg-1 against the same parasites was 94.2, 92.0, 93.5 and 93.8%, respectively, and at 10 mg kg-1 efficacy was 91.2, 97.6, 98.7 and 91.3%, respectively. No adverse effects due to treatment were seen in any of these trials.     

A comparison between the efficacy of thiabendazole and febantel on experimental trichinellosis in rats

Febantel at a dose level of 5 mg kg-1 had a lethal efficacy of 54.1% against the adult worm and 69.5% against the migrating larvae of Trichinella spiralis in rats. When administered at 15 mg kg-1, it demonstrated lethal effects of 94.4, 92.5 and 74.7% against adult, young and encysted larvae, respectively. Infected rats treated with 300 mg kg-1 died. Thiabendazole had efficiencies of 96.4 and 83.3% against intestinal and migrating early muscle phases, respectively, and was 42% effective against the encysting phase.     

The anthelmintic efficacy of netobimin against naturally acquired gastrointestinal nematodes in sheep

The broad-spectrum anthelmintic efficacy of netobimin (SCH 32481, Schering Corporation) was evaluated using 30 cross-bred spring lambs with naturally acquired infections of gastrointestinal nematodes. Three groups of 10 animals each were allotted into either control (given a tap water drench as a placebo) or 7.5 and 20 mg kg-1 dosage groups (given the netobimin as an oral drench). Seven to fourteen days post-treatment, animals were necropsied and nematodes recovered by standard techniques. Examination of fecal samples taken on dates of necropsy showed median egg production was reduced in treated animals (61.98% with 7.5 mg kg-1 and 100% with 20 mg kg-1). The compound was highly effective in removal of adult nematodes representing a number of genera and species of trichostrongyloids at the 7.5 and 20 mg kg-1 dose levels (shown, respectively, below). These included Ostertagia spp., with O. circumcincta, O. trifurcata, O. ostertagi and Teladorsagia davtiani (96.20%; 100%), Trichostrongylus spp., with T. axei, T. vitrinus and T. colubriformis (100%; 98.72%), Nematodirus spp., with N. spathiger, N. filicollis and N. battus (100% both levels) and Haemonchus contortus (100% both levels). High efficacies against other species of nematodes (at both dose levels) were not statistically significant (Cooperia spp., Chabertia ovina and Oesophagostomum venulosum). At 20 mg kg-1, netobimin significantly reduced populations of early and late fourth stage larvae of Ostertagia spp. by 100%. The overall efficacy (all life stages included) was 90.16% at 7.5 mg kg-1 and 98.77% at 20 mg kg-1 dose levels. No adverse reactions or signs of toxicosis were observed.     

Factors affecting the efficacy of ivermectin against Heligmosomoides polygyrus (Nematospiroides dubius) in mice

The efficacy of ivermectin against Heligmosomoides polygyrus was investigated in 5 mouse strains (CFLP, NIH, C57Bl10, BALB/c and CBA) using a variety of dose levels, and subcutaneous and oral administration. Heligmosomoides polygyrus were not completely eliminated when 5 mg kg-1 of ivermectin was given 6 days after infection, but 10 mg kg-1 was totally effective. Significant mouse-strain variation in drug efficacy was detected, NIH mice requiring treatment with higher doses than CFLP mice in order to bring about a comparable level of larvicidal activity. Ivermectin was more effective when given subcutaneously than when given orally, regardless of the dose administered or the strain of mouse tested. The anthelmintic effect of the treatment was more persistent in CFLP mice given 20 mg kg-1 subcutaneously than in NIH mice or in mice treated orally, and a 20-day interval between administration and infection was insufficient to prevent inhibition of parasite survival. Ivermectin was shown to be totally effective at 20 mg kg-1 given subcutaneously in killing immune arrested larvae of H. polygyrus.     

The effect of fenbendazole on nematode parasites in experimentally infected lambs.

Fenbendazole given orally to experimentally infected lambs at a dose rate of 5 mg per kg was found to be 100 per cent effective against three and 10-day larave and also against 20-day adults of H contortus, O circumcincta, N battus and T colubriformis. The same dose was also 100 per cent effective against 10-day, 17-day larvae and 27-day adult D filaria.     

Anthelmintic efficacy of febantel paste in naturally infected calves

The purpose of the present study was to verify results of the lowest dose (5 mg kg-1) of febantel evaluated in an earlier trial in which there were no differences in efficacies of three dose rates (5, 7.5 and 10 mg kg-1 body weight) against natural gastrointestinal nematode infections of cattle. Fourteen Angus calves (mean weight and age of 155 kg and 525 days, respectively), from the same farm, with relatively heavy (mean of 448 eggs g-1 feces (epg] parasite burdens were selected. After an adjustment period of 8 days in drylot, beginning on 25 July, seven calves were treated with a 45.5% paste formulation of febantel. On Day 7 post-treatment, calves were necropsied for determination of residual worms. Rectal fecal samples were obtained prior to adjustment, at treatment, 5 days post-treatment and at necropsy. On both Day 5 post-treatment and at necropsy a mean of less than 1 epg was recovered from treated calves compared with 765 and 1566 epg, respectively, in control calves. Worms counts at necropsy revealed an efficacy of 98.5% against all adult abomasal worms (Haemonchus placei, 100%, P less than 0.02; Trichostrongylus axei, 99.4%, P less than 0.0001; Ostertagia ostertagi, 90.5%, P less than 0.0002). Treatment was 100% efficacious against adult small and large intestinal worms. However, numbers of Bunostomum phlebotomum, O. radiatum and Trichuris spp. recovered in the control calves were too low to enable a reliable test of drug efficacy. Treatment was not effective against either mucosal or luminal fourth stage larvae of abomasal O. ostertagi.(ABSTRACT TRUNCATED AT 250 WORDS)     

Use of L4 larvae of Nippostrongylus brasiliensis for the in vivo screening of anthelmintic drugs.

Five groups of Wistar rats were subcutaneously infected with 5,000 L3 stage larvae of Nippostrongylus brasiliensis. Four groups were dosed orally with 5, 10, 15, and 20 mg/kg body weight of albendazole at 5 h postinfection, and one group served as an untreated control. The animals were euthanized and the intestines were dissected out 72 h postinfection and were incubated on a Baermann's apparatus to recover L4 stage larvae. No larvae were recovered from the 20 mg/kg albendazole-treated group, and means of 15, 33, and 175 L4 larvae were recovered from the 15, 10, and 5 mg/kg albendazole-treated groups, respectively. Levamisole and fenbendazole were also tested using the same procedure. Means of 100 and 1,887 L4 larvae were obtained from the 50 and 10 mg/kg of levamisole-treated groups respectively; while, 191 and 583 L4 larvae were recovered from rats treated with 50 and 10 mg/kg of fenbendazole, respectively. These results indicate that the L4 stage of N. brasiliensis could be useful for in vivo screening of new nematocide drugs.     

Efficacy of albendazole for treatment of naturally acquired nematode infections in Washington cattle.

Albendazole, methyl 5-propylthio-1H-benzimidazol-2-yl carbamate, was given as a bolus (7.68 to 8.18 mg/kg of body weight) to cattle naturally infected with gastrointestinal nematodes and lungworms in a controlled trial. Over 99% of adult Ostertagia ostertagi, Trichostrongylus longispicularis, Cooperia oncophora, Nematodirus helvetianus, and Dictyocaulus viviparus were removed by the treatment. Efficacy against immature O ostertagi, early fourth-stage O ostertagi, and Oesophagostomum radiatum was 95.2%, 86.6%, and 96.7%, respectively. In a field trial, the same compound administered in a paste formulation (at approximately 7.5 mg/kg) eliminated over 99% of strongylin and Moniezia eggs from feces of treated cattle.     

The anthelmintic efficacy of albendazole against Fasciola hepatica and benzimidazole resistant strains of Haemonchus contortus and Trichostrongylus colubriformis in sheep.

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.     

The effects of single and multiple doses of thiabendazole on growing and arrested stages of the rabbit stomach worm Obeliscoides cuniculi

Preliminary observations, using 5 rabbits carrying long-standing infections, indicated that single doses of thiabendazole were effective against adult O. cuniculi and that repeated doses may have had some effect on arrested larvae. A multiple dosing regime, consisting of 1 dose at 110 mg kg-1 body weight followed by 8 doses at 70 mg kg-1 body weight at 4-h intervals, was successful in removing 99.12% of developing worms and 86.04% of arrested larvae.     

国产三氯苯咪唑驱除山羊肝片形吸虫效果试验

以国产三氯苯咪唑对自然感染肝片形吸虫的山羊进行了驱虫试验，并以硝氯酚为药物对照。结果表明，三氯本咪唑5mg/kg体重的剂量对肝片形吸虫成虫和童虫的驱虫率分别为99.3%和92.9%，驱净率为75％；三氯苯咪唑10mg/kg体重的剂量对肝片形吸虫成虫和童虫的驱虫率均为100％，驱净率为100％；硝氯酚5mg/kg体重剂量对肝片形吸虫成虫驱虫率为100％，但对童虫的仅为74.3%，而驱净率仅为60％。在整个试验期间试验羊均无不良反应。     

Efficacy of moxidectin against an ivermectin-resistant strain of Haemonchus contortus in sheep.

The efficacy of moxidectin was determined against ivermectin-susceptible and resistant strains of Haemonchus contortus. At the onset of the trial, 40 lambs were each infected with 5000 third stage larvae of one of two strains of Haemonchus contortus. The lambs were randomly sorted into eight treatment groups 28 days post-infection and were treated as follows: Group 1, susceptible strain with no treatment; Group 2, resistant strain with no treatment; Group 3, susceptible strain treated with 0.2 mg moxidectin kg-1 body weight; Group 4, resistant strain treated with 0.2 mg moxidectin kg-1; Group 5, resistant strain treated with 0.4 mg moxidectin kg-1; Group 6, susceptible strain treated with 0.2 mg ivermectin kg-1; Group 7, resistant strain treated with 0.4 mg ivermectin kg-1; Group 8, resistant strain treated with 0.8 mg ivermectin kg-1. The lambs were killed 1 week post-treatment. Comparisons were made among groups based on the number of eggs per gram of feces on the day of treatment and the numbers of worms recovered from each lamb. Both moxidectin and ivermectin were effective in removing susceptible Haemonchus with efficacies of 100% and 99.7%, respectively. The efficacy of moxidectin against the resistant strain was 99.9% and 100% at 0.2 mg kg-1 and 0.4 mg kg-1, respectively, whereas there were only 38.8% and 53.1% efficacies in the lambs treated with 0.4 mg ivermectin kg-1 and 0.8 mg kg-1 body weight, respectively.     

Pharmacokinetics, urinary excretion and dosage regimen of diminazene in crossbred calves

The pharmacokinetics, urinary excretion and dosage regimen of diminazene were investigated in crossbred male calves following a single intramuscular dose (3.5 mg x kg-1). Following intramuscular administration, the pharmacokinetics of diminazene was described with a one-compartment open model. The absorption rate constant and absorption half-life were 9.86 +/- 3.06 h-1 and 0.121 +/- 0.40 h, respectively. The value of elimination half-life was 107.5 +/- 8.50 h. The apparent volume of distribution was 0.74 +/- 0.07 L x kg-1. Systemic availability following intramuscular administration was 91.7%. Approximately 65% of the administered dose of diminazene was eliminated in the urine within 24 h of its intramuscular administration. Diminazene was bound to plasma proteins to the extent of approximately 32%. The satisfactory intramuscular dosage regimen of diminazene for calves would be 2.24 mg x kg-1 followed by 1.5 mg x kg-1 at 7 days.     

Efficacy of paraherquamide against immature Trichostrongylus colubriformis in the gerbil (Meriones unguiculatus)

Paraherquamide was 98 to 100 per cent effective against six-day-old Trichostrongylus colubriformis infections in gerbils when given as single oral doses of 1.56 mg kg-1 and above. Doses of 0.78 or 0.39 mg kg-1 were 96 and 66 per cent effective, respectively. A single oral dose of 200 mg kg-1 was well tolerated.     

Anthelmintic efficacy of netobimin against naturally acquired gastrointestinal nematodes in yearling heifers

The efficacy of netobimin (Coded SCH 32481, Schering Corporation) in removing naturally acquired gastrointestinal nematode infections was evaluated in 10 treated and 10 untreated (control) yearling beef heifers. The anthelmintic was administered as an oral drench at a dose level of 7.5 mg kg-1 body weight. Fecal egg per gram (EPG) counts were reduced with netobimin by 98% (P less than or equal to 0.01) at both 1 and 2 weeks post-treatment (PT). The compound was highly effective in removing Oesophagostomum radiatum (100% at P less than or equal to 0.01), Cooperia spp. (97.66% at P less than or equal to 0.01) and Nematodirus helvetianus (100%, although not significant), but was ineffective against immature Ostertagia ostertagi (3.19%) and only moderately effective against adult forms (66.14% at P less than or equal to 0.05). The low efficacy against adult O. ostertagi was partially attributed to the maturation of fourth-stage larvae, not removed by the 7.5 mg kg-1 treatment, during the 14-day treatment-slaughter interval. Efficacy against Trichuris spp. could not be evaluated due to low levels and unequal numbers of worms recovered in the groups. The overall efficacy against adult species, excluding Trichuris spp., was 67.40% (P less than or equal to 0.05). No adverse reactions or signs of toxicosis were observed in heifers treated with netobimin.     

Relapses in dogs experimentally infected with Trypanosoma brucei and treated with diminazene aceturate or isometamidium chloride

Twenty dogs of mixed local East African breeds were used. Five of the dogs were uninfected controls and 15 were infected with T. brucei (ILRAD 273). Five of the infected dogs were untreated controls, five were treated with a high curative dose of diminazene aceturate, (7 mg kg-1 body weight (wt.), and five were given a subcurative dose of isometamidium chloride (1 mg kg-1 body wt.). The drugs, given at 8 days post infection (d.p.i..), led to apparent recovery. The antibody titres, however, remained high in both groups and at 42-49 d.p.i. there was at least one relapse in each treatment group. Parasite populations from relapsed animals were more resistant to the drugs than the original infecting populations. The implications of these findings are discussed.     

吸绦净和吡喹酮治疗小鼠微小膜壳绦虫病比较试验

本研究观察了吸绦净注射液对自然感染微小膜壳绦虫小鼠的治疗效果,同时与吡喹酮注射液进行了比较。将吸绦净和吡喹酮分别以０．７５ｇ／ｋｇ,０．５ｇ／ｋｇ和０．２５ｇ／ｋｇ体重剂量皮下注射,后间隔１小时粪检并于给药后３０分钟、１小时、２小时和３小时剖检,结果发现吸绦净用药组小鼠５小时￣８小时虫卵即转阴,而吡喹酮用药组２４小时转阴。剖检发现吸绦净对消化道中虫体有较明显损伤和破坏作用,而吡喹酮在相同剂量情况下     

Dynamics of the humoral immune response of calves infected and re-infected with Cooperia punctata

The dynamics of the humoral immune response of calves were analysed after primary infection and re-infection with the intestinal nematode Cooperia punctata. 12 male 5 month-old Holstein-Friesian calves were randomly divided into two groups A and B. At the beginning of the experiment Group A animals were each infected experimentally with a single oral dose of 130,000 infective third stage larvae (L3) of C. punctata. The animals of Group B were kept as non-infected controls. The two calves from Group A with the highest infections died of cooperiosis at 32 and 44 days after infection (DAI), respectively. On DAI 100 the calves were treated with the recommended dose of oxfendazole. On DAI 180 the remaining four calves of Group A and three animals of Group B (B1) were infected with 260,000 L3 of C. punctata, while the other three calves of Group B (B2) served as non-infected controls. Monitoring of the humoral immune response predominantly demonstrated an IgG1 response against both adult and L3 antigen of C. punctata. Moreover, re-infections increased the levels of these immunoglobulins. IgA levels were less increased than IgG1 and no significant increase was observed in IgG2 and IgM levels. Immunoblotting analysis showed that total IgG present in the serum of the primary infected animals mainly reacted against adult proteins of 12-14 and 17-20 kDa and against L3 proteins of 33 and 43 kDa. After re-infection total IgG reacted with the same adult proteins but also with an adult 29 kDa protein.