Efficacy of closantel plus albendazole liquid suspension against natural infection of gastrointestinal parasites in camels.

Oral administration of closantel in a dose of 10 mg/kg plus albendazole in a dose of 5 mg/kg liquid suspension was studied in 75 camels naturally infected with various types of gastrointestinal parasites. The camels involved were 15 pregnant she-camels, 20 non-pregnant she-camels and 40 male camels of various ages. Each camel received a single oral dose of closantel (10 mg/kg) plus albendazole (5 mg/kg) orally. Two weeks later, 20 camels of this group were re-dosed again with the same dose of the anthelmintic. Fecal samples were collected per rectum from all camels at the time of treatment and again 14 and 42 days post treatment. Fecal egg counts and generic determination of third stage larvae was performed. Results indicated that six different species of gastrointestinal tract parasites were identified in camels. Single treatment of closantel plus albendazole mixture reduced egg counts in camels by 100%, 100%, 98% and 77% for Haemonchus longistipes, Ascaris spp., Monezia expansa and Fasciola hepatica, respectively. However, administration of the drug twice on the base of 2 weeks apart significantly raised the efficacy of the drug for clearance of the parasites from 92.5% to 100% in camels infected with various parasites. Camels were not adversely affected by treatment.     

Evaluation of prevalence and clinical implications of anthelmintic resistance in gastrointestinal nematodes in goats

OBJECTIVE: To determine prevalence of resistance to all anthelmintics that are commonly used to treat gastrointestinal nematodes (GINs) in goats. DESIGN: Prospective study. ANIMALS: 777 goats. PROCEDURE: On each farm, goats were assigned to 1 of 5 treatment groups: untreated controls, albendazole (20 mg/kg [9.0 mg/lb], p.o., once), ivermectin (0.4 mg/kg [0.18 mg/lb], p.o., once), levamisole (12 mg/kg [5.4 mg/lb], p.o., once), or moxidectin (0.4 mg/kg, p.o., once), except on 3 farms where albendazole was omitted. Fecal samples were collected 2 weeks after treatment for determination of fecal egg counts (FECs), and percentage reductions were calculated by comparing data from anthelmintic-treated and control groups. Nematode populations were categorized as susceptible, suspected resistant, or resistant by use of guidelines published by the World Association for the Advancement of Veterinary Parasitology. RESULTS: Resistance to albendazole was found on 14 of 15 farms, and resistance to ivermectin, levamisole, and moxidectin was found on 17, 6, and 1 of 18 farms, respectively. Suspected resistance to levamisole and moxidectin was found on 4 and 3 farms, respectively. Resistance to multiple anthelmintics (albendazole and ivermectin) was found on 14 of 15 farms and to albendazole, ivermectin, and levamisole on 5 of 15 farms. Mean overall FEC reduction percentages for albendazole, ivermectin, levamisole, and moxidectin were 67, 54, 94, and 99%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Anthelmintic resistance in GINs of goats is highly prevalent in the southern United States. The high prevalence of resistance to multiple anthelmintics emphasizes the need for reexamination of nematode control practices.     

Efficacy of three broad-spectrum anthelmintics against gastrointestinal nematode infections of goats

Groups of 10 goats, harbouring both naturally acquired and experimental infections of gastrointestinal nematodes, were drenched with either levamisole (5 mg kg-1), albendazole (3.8 mg kg-1) or parbendazole (15 mg kg-1), or remained untreated. Haemonchus contortus was the numerically dominant infection, with Strongyloides papillosus, Trichostrongylus colubriformis and Oesophagostomum columbianum also present. At 5-6 days post-treatment, goats were killed and necropsied. Post-mortem worm counts showed that the reduction in mean total worm burdens was 57.4% in levamisole-treated animals, 71.1% in the albendazole group and 85.1% in the parbendazole group. Reductions for H. contortus were 80.2, 87.9 and 83.9% in the levamisole-, albendazole- and parbendazole-treated groups, respectively. These data indicate that the anthelmintics in question are not being applied at an adequate dose rate for goats, and/or resistance to anthelmintics is occurring in the field in Pernambuco State, northeast Brazil.     

Metabolite concentrations in plasma following treatment of cattle with five anthelmintics

Plasma concentrations of anthelmintics and their metabolites were determined after cattle were treated at recommended dose rates and routes of administration. Fenbendazole, oxfendazole, febantel, albendazole and thiabendazole were given orally and oxfendazole was also administered with an intraruminal injector. After fenbendazole, oxfendazole and febantel were administered, fenbendazole, oxfendazole and fenbendazole sulphone were all detected in plasma in each case. However, there were marked differences between the three anthelmintics in the peak concentrations and areas under the plasma concentration/time curve (AUC) of these three metabolites. Intraruminal administration of oxfendazole produced higher AUC for fenbendazole and fenbendazole sulphone than did oral administration. Albendazole sulphoxide and sulphone were detected in cattle plasma after albendazole administration but no parent drug was present. These metabolites disappeared more rapidly in cattle than has been reported for sheep. Only 5(6)hydroxythiabendazole was detected in cattle plasma after thiabendazole treatment.     

Susceptibility assay of Haemonchus contortus to commonly used anthelmintics in Jimma, southwest Ethiopia

An experimental study to investigate the susceptibility pattern of Haemonchus contortus to commonly used anthelmintics (albendazole, tetramisole, ivermectin, and triclobendazole) was conducted between June and September 2009. Adult H. contortus parasites were collected from a total of 30 sheep slaughtered at Jimma municipal abattoir. The anthelmintics were assessed for egg hatch inhibition ability against H. contortus eggs. The eggs (500 eggs/ml) were incubated with different concentrations (0.25, 0.125, 0.0625, 0.03125, and 0.015625?μg/ml) at 26°C for 48?h. Egg hatching inhibition of different anthelmintics at different concentrations was recorded. The overall mean percent inhibition showed that there was a significant difference (p?相似文献   

The efficacy of fenbendazole and albendazole against immature and adult stages of benzimidazole-resistant sheep trichostrongylids

The efficacy of two recently introduced benzimidazole anthelmintics, albendazole and fenbendazole, was determined for six-day, 10-day and adult stages of resistant strains of Haemonchus contortus and Trichostrongylus colubriformis. Albendazole, at 3.8 mg/kg reduced H contortus worm counts by 92.4, 70.8 and 67.1 per cent while fenbendazole, at 5.0 mg/kg, reduced worm burdens by 51.7, 95.5 and 93.4 per cent against six-, 10- and 25-day-old parasites respectively. For T colubriformis, the corresponding reductions with albendazole were 97.7, 95.8 and 64.9 per cent and for fenbendazole 29.0, 66.3 and 33.4 per cent. Compared with susceptible strains of H contortus and T colubriformis, for which therapeutic doses of benzimidazole anthelmintics are generally highly active against all stages of development, the present results show that these drugs do not have a uniform level of activity against all developmental stages of resistant strains.     

Anthelmintic resistance in cattle nematodes in northwestern São Paulo State, Brazil

The present study was carried out in the northwestern region of S?o Paulo State, Brazil, to determine the anthelmintic resistance status in cattle naturally infected with gastrointestinal nematodes. The anthelmintics tested were levamisole phosphate (Ripercol, Fort Dodge), albendazole sulphoxide (Ricobendazole, Fort Dodge), ivermectin (Ivomec, Merial) and moxidectin (Cydectin, Fort Dodge), administered at the doses recommended by the manufacturers. From April 2002 to May 2004, 25 cattle farms were evaluated. On each farm, steers were divided into treatment and control (not treated) groups based on fecal egg counts (FEC). Between 7 and 10 days after the anthelmintics administration, fecal samples were collected from each animal for post-treatment FEC. Fecal cultures from each group were also prepared for larval identification. After treatment, mean FEC reduction (FECR) in treatment groups (compared with control groups) was assessed on each farm. FECR was lower than 90% on 23 farms after ivermectin treatment. On 19 farms, FECR of 100% was recorded following moxidectin treatment; on the remaining 6, FECR ranged from 90% to 97.2%. After albendazole treatment, FECR was higher than 90% on 20 farms and ranged from 47.4% to 84.6% on other 5. After levamisole treatment, FECR was higher than 90% on 23 farms and equal to 47.4% and 73.7% on other 2 farms. Results indicated the presence of resistant Cooperia spp. and Haemonchus spp., especially to ivermectin; on some farms, resistance to albendazole and levamisole was also observed.     

Prevalence of anthelmintic resistance on 62 beef cattle farms in the North Island of New Zealand

AIM: To establish the prevalence of anthelmintic resistance in parasitic nematodes on a random sample of beef cattle herds in the North Island of New Zealand. METHODS: A cross-sectional prevalence study was conducted using a standardised faecal nematode egg count (FEC) reduction (FECR) test (FECRT) for ivermectin, levamisole and albendazole on 60 calves on each of 62 farms in the North Island chosen at random from farms that conformed with the selection criteria. Resistance to an anthelmintic was inferred when there was <95% reduction in FEC 7-10 days after treatment. Larval cultures were performed for all control groups and for treated groups for which resistance was evident. RESULTS: Of the farms that completed the FECRT, 4/61 (7%) showed > or =95% reduction in FEC for all anthelmintics tested. Resistance to ivermectin was evident on 56/61 (92%) farms, to albendazole on 47/62 (76%) farms, and to both ivermectin and albendazole on 45/61 (74%) farms. Resistance to levamisole was evident on only 4/62 (6%) farms. The parasites most prevalent in resistant populations cultured were Cooperia spp. On 45/61 (74%) farms where Cooperia spp were present in sufficient numbers, resistance to both ivermectin and albendazole was evident. No cases of levamisole-resistant Cooperia spp were detected. Resistance of Ostertagia spp to ivermectin was evident on 4/45 (9%) farms, to albendazole on 15/46 (35%) farms, and to levamisole on 4/46 (9%) farms. CONCLUSION: Anthelmintic resistance in parasitic nematodes of cattle is common in the North Island of New Zealand. Beef farmers need to be aware of the risks posed by anthelmintic resistance, and routine FECR testing is recommended to ensure optimal productivity and to guide decision-making when purchasing anthelmintics to be used on-farm.     

Field evaluation of a mixture of albendazole sulphoxide and levamisole against Ostertagia and Trichostrongylus spp in sheep

The efficacy of a mixture of albendazole sulphoxide and levamisole, 3.6 and 8.25 mg/kg respectively, at single and double dose rates, was compared with the recommended dose rate of each anthelmintic alone. The comparison was conducted on groups of 6 to 14-week-old lambs on 22 farms, 16 of which had evidence of multiple resistance to benzimidazole and levamisole. A single dose of the mixture reduced mean egg counts by 95% on half the farms with multiple resistance and on all the remaining farms. Consequently, the mixture should be included in an assessment of effective anthelmintics on farms to determine its value for nematode control. A double dose rate of mixture was effective on all but 4 farms. Reductions caused by the mixture were due to the additive actions of the drugs on 18 of 22 farms; synergistic action was noted on only 3 farms. It was concluded that the mixture of albendazole sulphoxide and levamisole offered many farmers an effective anthelmintic for use in preventive control programs. Recommendations for such programs include annual rotation of effective anthelmintics as a means of delaying selection for drug resistance.     

Efficacy of albendazole and moxidectin and resistance to ivermectin against Libyostrongylus douglassii and Libyostrongylus dentatus in ostriches

Anthelmintic resistance has emerged globally as a problem amongst nematode of livestock and has been particularly well documented in equine and small ruminants. There are no studies regarding the efficacy of anthelmintics against the hematophagous nematodes in ostriches, Libyostrongylus dentatus; and just a few on L. douglassii. Here the efficacy of albendazole, ivermectin and moxidectin were evaluated against these two species in an ostrich farm in Minas Gerais state, Brazil. The feces were collected on the day of treatment and after 13days of an oral dose of albendazole (6mg/kg), or an injected dose (0.2mg/kg) of ivermectin or moxidectin. The fecal egg count reduction test and coprocultures were performed to determine possible resistance against the drugs used. An efficacy of 60% was found for ivermectin, while albendazole and moxidectin were 100% effective. Both worm species appeared to have reduced sensitivity to ivermectin.     

Prevalence of anthelmintic resistance on 62 beef cattle farms in the North Island of New Zealand

AIM: To establish the prevalence of anthelmintic resistance in parasitic nematodes on a random sample of beef cattle herds in the North Island of New Zealand.

METHODS: A cross-sectional prevalence study was conducted using a standardised faecal nematode egg count (FEC) reduction (FECR) test (FECRT) for ivermectin, levamisole and albendazole on 60 calves on each of 62 farms in the North Island chosen at random from farms that conformed with the selection criteria. Resistance to an anthelmintic was inferred when there was <95% reduction in FEC 7-10 days after treatment. Larval cultures were performed for all control groups and for treated groups for which resistance was evident.

RESULTS: Of the farms that completed the FECRT, 4/61 (7%) showed ≥95% reduction in FEC for all anthelmintics tested. Resistance to ivermectin was evident on 56/61 (92%) farms, to albendazole on 47/62 (76%) farms, and to both ivermectin and albendazole on 45/61 (74%) farms. Resistance to levamisole was evident on only 4/62 (6%) farms. The parasites most prevalent in resistant populations cultured were Cooperia spp. On 45/61 (74%) farms where Cooperia spp were present in suffi cient numbers, resistance to both ivermectin and albendazole was evident. No cases of levamisole-resistant Cooperia spp were detected. Resistance of Ostertagia spp to ivermectin was evident on 4/45 (9%) farms, to albendazole on 15/46 (35%) farms, and to levamisole on 4/46 (9%) farms.

CONCLUSION: Anthelmintic resistance in parasitic nematodes of cattle is common in the North Island of New Zealand. Beef farmers need to be aware of the risks posed by anthelmintic resistance, and routine FECR testing is recommended to ensure optimal productivity and to guide decision-making when purchasing anthelmintics to be used on-farm.     

Multiple anthelmintic resistance on a goat farm in Hawassa (southern Ethiopia)

A study was conducted to determine the presence of anthelmintic resistance on Hawassa University goat farm in southern Ethiopia. The 180 goats were stratified by age and sex and randomly assigned to treatment groups (albendazole, tetramisole and ivermectin and untreated control). Each treatment group included 15 goats and treatments were administered according to weight of each goat with 7.5 mg/kg bw albendazole, 22.5 mg/kg bw tetramisole and 0.2 mg/kg bw ivermectin dose rates recommended by scientists. Faecal samples were collected on day 0 before treatment, and again on day 12 post treatment. Efficacy of all the drugs was assessed on day 12 post treatment by faecal egg count reduction test (FECRT). Multiple anthelmintic resistance in Haemonchus spp. against albendazole, tetramisole and ivermectin was recorded in all age categories of the goats. Likewise, Trichostrongylus/Teladorsagia spp. showed resistance against ivermectin. Coprocultures from all pre- and post-treatments revealed the predominance of Haemonchus spp. Resistance against anthelmintics is attributed to the high frequency of treatment and low dosage of treatment practices on the farm. Large scale studies, however, are needed to assess the current status of anthelmintic resistance against the most commonly used anthelmintics in different agroecology, species of animals and management systems in Ethiopia.     

THE ISOLATION OF A FIELD STRAIN OF HAEMONCHUS CONTORTUS IN QUEENSLAND SHOWING MULTIPLE ANTHELMINTIC RESISTANCE

SUMMARY Following the apparent failure of levamisole to control infections of Haemonchus contortus in sheep at Lawes in south eastern Queensland, a strain of this parasite was isolated at the Animal Research Institute, Yeerongpilly. This strain was used to infect sheep at Yeerongpilly and the Merrindale Research Station, Victoria where four experiments to classify the resistance pattern of the parasite were carried out. Resistance to thiabendazole was first suspected in 1969, and these experiments confirmed that resistance to this drug was still present. They also showed that a strong degree of resistance had been developed to both levamisole and morantel tartrate. Other benzimidazole anthelmintics and also the organophosphorus compound naphthalophos were only moderately effective against the original isolate but rafoxanide, nitroxynil and phenothiazine were almost 100% effective. Other highly effective chemicals were disophenol and closantel. After passaging the strain for four generations with both levamisole and albendazole, resistance to both naphthalophos and the newer benzimidazole anthelmintics increased dramatically. This is the first report of a field strain of H. contortus exhibiting resistance to benzimidazole, non-benzimidazole and organophosphorus anthelmintics.     

Comparative Disposition Kinetics of Albendazole in Sheep Following Oral and Intraruminal Administration

The pharmacokinetics of albendazole was studied in sheep following single oral and intraruminal administration at nematocidal dose rates. The disposition curves of its metabolites indicated increased uptake of the drug in sheep following intraruminal as compared to oral dosing (p<0.05). The increased bioavailability of benzimidazole anthelmintics given by the intraruminal route could be exploited for optimizing the use of anthelmintic for sustained parasite control in small ruminants.     

The dose response of several benzimidazole anthelmintics against resistant strains of Haemonchus contortus and Trichostrongylus colubriformis selected with thiabendazole

Dose response lines for eight benzimidazole anthelmintics and thiophanate were determined, using standardised strains of thiabendazole selected and resistant Haemonchus contortus and Trichostrongylus colubriformis. Against H contortus, thiophanate, thiabendazole, parbendazole and oxibendazole were inactive. Mebendazole was inactive at dose rates of 6.26 and 12.5 mg/kg, although significant activity occurred at 25 mg/kg. Fenbendazole, cambendazole, oxfendazole and albendazole demonstrated significant activity at dose rates equal to or greater than the recommended therapeutic level. Thiophanate was inactive against resistant T colubriformis. The remaining compounds only showed significant activity when used at dose rates in excess of the recommended therapeutic level. These results show that a side resistance exists among the benzimidazole anthelmintics and suggests that changes in dose response lines could be expected to occur if resistant strains are selected with benzimidazoles other than thiabendazole.     

The disposition kinetics of albendazole following the administration of single and divided doses to cattle and buffalo

Concentrations of albendazole sulphoxide and its sulphone metabolite in plasma in cattle and buffalo were measured by high-performance liquid chromatography after single and divided intraruminal administration of albendazole at the recommended nematocidal and fasciolicidal dose rates of 7.5 and 15.0 mg/kg body weight, respectively. No significant differences in the plasma concentrations of the metabolites or their pharmacokinetic parameters were observed between cattle or buffalo at either dose rate. Pharmacokinetic analysis and the disposition curve of the metabolites indicated increased uptake of the drug in both cattle and buffalo when the same total amount of the drug was given in divided doses compared to a single dose (p<0.05). The divided dose schedules of administration could possibly be exploited to extend the life of the available benzimidazole anthelmintics.     

Prevalence of anthelmintic resistance on sheep farms in New Zealand

AIM: To establish the prevalence of anthelmintic resistance in parasitic nematodes on sheep farms in New Zealand. METHODS: A cross-sectional prevalence study was conducted, using a standardised faecal nematode egg count (FEC) reduction (FECR) test (FECRT) for ivermectin, at a full (0.2 mg/kg) and half (0.1 mg/kg) dose rate, and albendazole, levamisole and albendazole-levamisole in combination, on 60 lambs (n=10 per group) on farms selected from throughout New Zealand. Farms that conformed with selection criteria were chosen at random (n=80) or with a history of suspected resistance to macrocyclic lactone (ML) anthelmintics (n=32). Resistance to an anthelmintic was inferred when there was <95% reduction in FEC 7-10 days after treatment. Larval cultures were performed for all control groups and for treated groups for which resistance was evident. RESULTS: Of the farms randomly selected, 36% showed > or =95% FECR for all anthelmintics tested; resistance to ivermectin at 0.1 and 0.2 mg/kg liveweight was evident on 36% and 25% of these farms, respectively. Resistance to both ivermectin (0.2 mg/kg) and levamisole was evident on 8/80 (10%) farms, to ivermectin and albendazole on 10/80 (13%) farms, and to ivermectin, levamisole and albendazole on 6/80 (8%) farms. The prevalence of resistance to a half dose of ivermectin tended to be more prevalent on farms with a history of suspected ML resistance (p=0.06). Resistance to albendazole was seen across all the main parasite genera, and to levamisole in Nematodirus, Ostertagia (= Teladorsagia) and Trichostrongylus species. Resistance to ivermectin was dominated by Ostertagia spp, although Cooperia, Nematodirus and Trichostrongylus species were also implicated. CONCLUSION: Anthelmintic resistance in parasitic nematodes of sheep is common in New Zealand. Not only was resistance to albendazole and levamisole common, but resistance to the ML, ivermectin, was at a higher prevalence than expected. Sheep farmers and advisors in New Zealand need to re-evaluate the way they manage parasites, and more research is urgently needed if the steady decline in anthelmintic susceptibility is to be halted.     

Effect of single and divided dose administration on thepharmacokinetics of albendazole in sheep and goat

The pharmacokinetics of albendazole were studied in sheep and goats following single and divided doseadministration at nematocidal and flukicidal dose rates. The disposition curves of the metabolites indicated increased uptake of the drug both in sheep and goats at divided dose schedules compared to single dose administration (P<0.05). The increased bioavailability of benzimidazole anthelmintics in divided dose schedules could improve their efficacy and help in extending their lives.     

Implications of Fungicidal Effects of Benzimidazole Compounds on Duddingtonia flagrans in Integrated Nematode Parasite Management in Livestock

An in vitro trial with carbendazim fungicide on the growth profile of the predatory fungus Duddingtonia flagrans was undertaken and in vivo trials in sheep and buffaloes, fed on chlamydospores of D. flagrans and administered albendazole anthelmintic, were conducted. Although no growth inhibition was detected at a carbendazim concentration of 0.05 ppm, growth inhibition was recorded of 50% and above at concentrations of 0.25 and 1.00 ppm (p < 0.001) and of around 90% at concentrations of 2.00 to 5.00 ppm (p <0.0001). Scanty recovery of the fungus was made from faecal culture 48 h following a single dose of albendazole both in sheep and buffaloes. However, profuse fungal recovery was made from 96 h post dosing onwards. When the drug was used as an intraruminal slow-release capsule, no faecal fungal recovery could be made from day 3 after administration of the capsule, when the albendazole sulphoxide concentration was around 1.0 microg/ml. However, profuse and scanty fungal recovery could be made on days 1 and 2, respectively, after administration of the capsule, when the plasma albendazole sulphoxide concentration was around 0.4 and 0.9 microg/ml, respectively. The implications for use of a combination of anthelmintics and biological control in sustainable parasite control programmes are discussed.     

数种驱虫药和化学药物对体内外鸡蛔虫产卵和虫卵发育的影响

为鉴定男性不育药和有些驱虫药对寄生蠕虫的不育作用,对培养在试管内的鸡蛔虫和卵胚,以及人工感染蛔虫的鸡分别进行了体内和体外试验。棉酚和硝基呋喃类的呋喃唑酮、呋喃西林、S_(73031)和S_(72055)均无抑制产卵和卵胚发育的作用,苯并咪唑类的丙硫咪唑、甲苯咪唑和噻苯咪唑以及吩噻嗪均有抑制产卵和卵胚发育的作用,它们的EMIC_(50)分别为0.006,1.326,0.029和0.052ppm。抑制产卵所需浓度远大于抑制卵胚发育所需浓度。吡喹酮和硫双二氯酚也不具有抑制产卵和卵胚成熟的作用。放线菌酮仅对试管内蛔虫有抑制产卵作用,但对体内蛔虫却无影响。