Rintal颗粒剂对绵羊消化道寄生虫的驱虫效果试验

用Rintal颗粒剂对绵羊进行了消化道线虫驱虫试验。结果表明当前剂量为5.0mg/kg体重时，Rintal颗粒剂对绵羊食道口线虫、细颈属线虫、毛圆线虫、夏伯特线虫、奥斯特线虫以及肺丝虫等虫卵减少率，虫卵转阴率、虫卵孵化第3期幼虫减少率和第3期幼虫转阴率均为100%，而且安全，使用方便，易于保管运输。     

放牧绵羊主要寄生虫病药物防治技术试验与示范效果观察

为评价伊维菌素注射剂的驱虫效果与对放牧绵羊线虫病及外寄生虫病的防治示范效果,选择1.5岁感染线虫和部分外寄生虫的绵羊150只,设伊维菌素注射剂0.1,0.2和0.3mg/kg体重剂量组和伊维菌素片剂对照组,进行驱虫效果评价;在冬季应用伊维菌素注射剂按0.2mg/kg体重剂量对放牧绵羊进行规模防治技术示范,检查防治效果和考核防治效益。结果:药效试验中伊维菌素注射剂0.2mg/kg对绵羊消化道线虫虫卵转阴率和减少率分别为93.3%,99.3%,对原圆科线虫幼虫转阴率和减少率分别为90.0%和96.1%;0.3mg/kg剂量对消化道线虫虫卵及原圆科线虫幼虫转阴率和减少率均为100.0%;0.1mg/kg剂量对消化道线虫虫卵转阴率和减少率分别为76.7%,88.6%,原圆科线虫幼虫转阴率和减少率分别为66.7%和86.1%。防治示范群绵羊消化道线虫虫卵转阴率为93.3%,虫卵减少率为96.8%;对原圆科线虫幼虫转阴率和减少率分别为90.0%和96.2%。同期检查未防治对照组虫卵EPG和幼虫数略有增加。技术示范群比未示范群每只成年羊平均多增重5.47kg、幼年羊成活率平均提高2.1个百分点。结果表明该防治技术对放牧绵羊主要寄生虫病高效安全,效益显著。     

爱普利注射剂对放牧绵羊体内外寄生虫的驱虫试验

应用爱普利注射剂,选择自然感染线虫和体外寄生虫的1.5岁放牧藏系绵羊100只,分别按0.1、0.2、0.3 mg/kg.b w剂量皮下注射给药,同时设伊维菌素注射剂药物对照组和阳性对照组,评价驱除放牧绵羊体内线虫与体外寄生虫的效果。结果显示:爱普利注射剂0.2、0.3 mg/kg剂量对放牧绵羊消化道线虫虫卵转阴率分别为95.0%和100.0%,减少率分别为98.4%和100.0%;网尾线虫幼虫转阴率和减少率均达100.0%,原圆科线虫幼虫转阴率分别为90.0%和100.0%,减少率分别为96.1%和100.0%;对主要线虫虫卵(幼虫)的平均有效率分别达98.0%和100.0%;第7d对绵羊颚虱、足颚虱的转阴率、杀虫率均达100%;对羊蜱蝇的转阴率分别为90.0%和100.0%,杀虫率分别达92.3%和100%;均达到了高效。爱普利注射剂0.1 mg/kg剂量对线虫虫卵(幼虫)的转阴率、减少率及对体外寄生虫的杀虫率均次于0.2、0.3 mg/kg剂量组。对照药物伊维菌素注射剂0.2 mg/kg剂量消化道线虫虫卵转阴率、减少率分别为95.0%和97.8%;网尾线虫幼虫转阴率和减少率均达100.0%,原圆科线虫幼虫转阴率、减少率分别为85.0%和94.3%;第7d绵羊颚虱、足颚虱的转阴率、杀虫率均达100%;羊蜱蝇转阴率、杀虫率分别为80.0%和90%。阳性对照组线虫虫卵(幼虫)与给药前无明显变化、3种体外寄生虫感染情况较给药前略有增加。绵羊皮下注射3个剂量爱普利注射剂,未出现任何异常反应。试验证明爱普利注射剂3个剂量对藏系绵羊线虫虫卵(幼虫)、3种体外寄生虫均有效,其中0.2 mg/kg剂量驱除放牧绵羊线虫高效安全经济。     

放牧绵羊主要寄生虫病高效低残留防治技术试验示范

为评价埃谱利诺菌素注射剂的驱虫药效与对放牧绵羊线虫病及外寄生虫病的防治示范应用效果,选择1.5岁感染线虫和部分外寄生虫的绵羊150只,设埃谱利诺菌素注射剂0.1,0.2和0.3 mg/kg体重剂量组和埃谱利诺菌素原料药对照组,进行驱虫效果评价,按0.2 mg/kg体重剂量进行规模防治技术示范,检查防治效果和考核防治效益。结果:药效试验中埃谱利诺菌素注射剂0.2 mg/kg剂量对绵羊消化道线虫虫卵转阴率和减少率分别为96.7%和99.3%,对原圆科线虫幼虫转阴率和减少率分别为90.0%和97.5%;0.3 mg/kg剂量对消化道线虫虫卵及原圆科线虫幼虫转阴率和减少率均为100.0%;0.1mg/kg剂量对消化道线虫虫卵转阴率和减少率分别为83.3%和90.4%,原圆科线虫幼虫转阴率和减少率分别为76.7%和88.9%。在冬季应用埃谱利诺菌素注射剂按0.2 mg/kg体重剂量对放牧绵羊进行规模防治技术示范,防治示范群绵羊消化道线虫虫卵转阴率和减少率分别为96.7%和97.7%;对原圆科线虫幼虫转阴率和减少率分别为93.3%和97.6%。同期检查未防治对照组绵羊虫卵EPG和幼虫数略有增加。埃谱利诺菌素注射剂0.2mg/kg剂量试验组给药后第1d绵羊体表的绵羊颚虱、足颚虱、羊蜱蝇活力旺盛;第3d绵羊颚虱、足颚虱大部分死亡干瘪,部分虫体移行到被毛表面,处于麻痹状态,活力较差;第7d检查对足颚虱的杀虫率达100%;绵羊颚虱全部死亡干瘪,杀虫率达100%;对羊蜱蝇的转阴率为83.3%。0.1mg/kg剂量,第3、7d检查杀灭效果次于上述剂量。未防治的对照组绵羊上述外寄生虫活力旺盛,感染情况与给药前无明显变化。同期检查技术示范群比未示范群每只成年羊平均少减重5.96kg、幼年羊成活率平均提高2.35个百分点。结果表明该防治技术对放牧绵羊主要寄生虫病高效安全,效益显著。     

奥芬达唑干混悬剂对黄牛线虫的驱除试验

应用奥芬达唑干混悬剂分别按5、10、15mg／kg．bw剂量1：2服给药，驱除黄牛自然感染线虫，投药后14d粪检结果：15mg／kg剂量试验组虫卵(幼虫)转阴率、减少率均为100％；10mg／kg剂量对消化道线虫虫卵转阴率909／5，减少率99．9％，原圆科线虫幼虫转阴率909／5，减少率94．6％；5mg／kg剂量对消化道线虫虫卵转阴率80％，减少率99．2％，对原圆科线虫幼虫转阴率70％，减少率91．1％；而对照组同期检查虫卵(幼虫)给药前后无明显变化。第21d剖检结果：15mg／kg、10mg／kg、5mg／kg剂量总计驱虫率分别达99．2％、97．4％和95．7％。均达到了高效。     

伊维菌素干混悬剂驱除绵羊寄生虫的扩大试验

应用伊维菌素干混悬剂,驱除绵羊体内线虫和体外寄生虫。结果:0.2mg/kg体重剂量对消化道主要线虫及网尾线虫的虫卵(幼虫)转阴率、减少率均为100%,原圆科线虫幼虫转阴率和减少率分别为91.3%、91.8%,对线虫的总计驱虫率98.9%:对绵羊颚虱的杀虫率为100%。结果证明:伊维菌素干混悬剂0.2mg/kg剂量一次用药,驱除绵羊主要线虫和虱等寄生虫,高效安全。     

伊维菌素浇泼剂防治绵羊寄生虫病的效果观察

应用伊维菌素浇泼剂,驱除绵羊体内线虫和体外寄生虫,结果表明,0．5mg／kg体重剂量对主要7属消化道线虫和网尾线虫的虫卵（幼虫）转阴率、减少率均为100％,对原圆科线虫幼虫转阴率、减少率分别为87．59／6和91．3％,对线虫的总计驱虫率为99．04％;对绵羊颚虱的杀虫率达100％。表明伊维菌素浇泼剂0．5mg／kg剂量一次用药,驱除绵羊体内线虫和体外绵羊颚虱等寄生虫,高效安全。     

倍克虫复合制剂对放牧绵羊线虫的驱虫效果

应用不同剂量倍克虫复合制剂(伊维菌素,丙硫苯咪唑),对放牧绵羊胃肠道线虫,肺线虫等进行驱除试验,结果表明：中剂量组(伊维菌素0．2mg／kg,丙硫苯咪唑10mg／kg)绵羊的消化道线虫虫卵转阴率达100％,减少率达100％,原圆科线虫幼虫转阴率达70％,减少率为77．35％。     

埃谱利诺菌素注射剂对藏羊线虫与寄生期幼虫的驱虫效果

应用埃谱利诺菌素注射剂,选择自然感染线虫的1岁藏系绵羊150只,分别按0.1、0.2、0.3 mg/kg体重剂量皮下注射给药,驱除藏羊线虫,同时设伊维菌素注射剂药物对照组和阳性对照组。结果显示:①埃谱利诺菌素注射剂0.2、0.3 mg/kg体重剂量对藏羊消化道线虫虫卵转阴率分别为93.3%和100.0%,减少率分别为99.18%和100.0%;对网尾线虫幼虫转阴率和减少率均达100.0%,原圆科线虫幼虫转阴率分别为90.0%、100.0%,减少率分别为95.79%和100.0%;对线虫成虫的总计驱虫率分别为98.83%和99.96%,对线虫寄生阶段幼虫的总计驱虫率分别为96.42%和99.17%。②0.1 mg/kg剂量对线虫虫卵(幼虫)的转阴率、减少率、驱虫率均次于0.2、0.3 mg/kg体重剂量组。③对照药物伊维菌素注射剂0.2 mg/kg体重剂量对消化道线虫、原圆科线虫幼虫转阴率和减少率、对线虫成虫及其寄生阶段幼虫的总计驱虫率与同剂量埃谱利诺菌素注射剂基本一致。④藏羊皮下注射试验剂量未出现任何异常反应。试验证明埃谱利诺菌素注射剂0.2 mg/kg体重剂量驱除线虫高效安全。     

伊维菌素注射剂对绵羊主要寄生虫病的防治试验

应用伊维菌素注射剂按0.2mg/kg体重剂量一次皮下注射给药,采用粪检法和体表检查法,进行放牧绵羊主要寄生虫病防治示范.结果:对绵羊主要消化道线虫虫卵转阴率、减少率分别为96.7％和99.1％,对原圆科线虫幼虫转阴率、减少率分别为89.5％和91.6％,对绵羊颚虱的杀虫率达100％.全部防治绵羊投药后未发生异常反应.应用效果证明:伊维菌素注射剂防治绵羊主要寄生虫病高效、安全、经济.     

Feasibility of genus-specific real-time PCR for the differentiation of larvae from gastrointestinal nematodes of naturally infected sheep

Results of real-time PCR analysis of coproculture third stage larvae (L3) using genus specific TaqMan minor groove binder probes were compared with the results of morphological differentiation of L3 after coprocultured and direct morphological worm differentiation from gastrointestinal samples of eight sheep with naturally acquired nematodes infections. Faecal egg counts prior to postmortem confirmed infections with trichostrongyles with a geometric mean count of 4828 eggs per gram for all sheep. Individual egg counts correlated positively with total worm counts (correlation coefficient 0.794). Five different nematode species and one genus were found in the abomasi and small intestines: Cooperia curticei, Haemonchus contortus, Nematodirus spp., Teladorsagia (Ostertagia) circumcincta, Trichostrongylus axei and Trichostrongylus colubriformis. Coproculture of faecal eggs yielded five of these, Cooperia spp., Haemonchus spp., Ostertagia/Teladorsagia spp. and Trichostrongylus spp. Comparison between morphological L3 and worm differentiation data showed high congruence (94%). The agreement between PCR analysis of L3 after coproculture and direct morphological worm differentiation was 84%. Thus, real-time PCR was found to be suitable as a speedy and reliable diagnostic tool for the assessment of gastrointestinal nematode infections of ruminants in the field.     

Observations on the free-living stages of cattle gastrointestinal nematodes

A 4-year study on the free-living stages of cattle gastrointestinal nematodes was conducted to determine (a) the development time from egg to infective larvae (L3) inside the faecal pats, (b) the pasture infectivity levels over time, and (c) the survival of L3 on pasture. Naturally infected calves were allowed to contaminate 16 plots on monthly basis. Weekly monitoring of eggs per gram of faeces (epg) values and faecal cultures from these animals provided data for the contamination patterns and the relative nematode population composition. At the same time, faecal pats were shaped and deposited monthly onto herbage and sampled weekly to determine the development time from egg to L3. Herbage samples were collected fortnightly over a 16-month period after deposition to evaluate the pasture larval infectivity and survival of L3 over time. The development time from egg to L3 was 1-2 weeks in summer, 3-5 weeks in autumn, 4-6 weeks in winter, and 1-4 weeks in spring. The levels of contamination and pasture infectivity showed a clear seasonality during autumn-winter and spring, whilst a high mortality of larvae on pasture occurred in summer. Ostertagia spp., Cooperia spp. and Trichostrongylus spp. were predominant and a survival of L3 on pasture over a 1-year period was recorded in this study.     

EFFECTS OF A PREVENTIVE AND SUPPRESSIVE CONTROL SCHEME ON THE DEVELOPMENT OF THIABENDAZOLE-RESISTANCE IN OSTERTAGIA SPP

SUMMARY Three years after the start of an experiment to assess the merits of thiabendazole (TBZ) treatment of trichostrongylid parasites in weaner sheep, field isolates of Ostertagia spp and Trichostrongylus spp were made from weaner sheep treated under one of three treatment schemes. Treatment frequencies were “nil”, “planned” (5 or 6/year) and “regular” (every 3 weeks). In addition an isolate was taken from a group of “tracer” sheep drenched with TBZ every 10 days. Resistance to TBZ was assessed using an in vitro egg hatch assay, pre- and post-treatment faecal egg counts and a controlled anthelmintic efficiency test. Pre- and post-treatment egg counts revealed the presence of TBZ-resistance in field isolates of mixed species. Egg hatch assays indicated a level of resistance for Ostertagia spp which was proportional to the frequency of TBZ treatment. The “planned”, “regular” and “tracer” strains of Ostertagia spp had resistance ratios for eggs of 4, 13 and 15 respectively when compared to the “nil” strain. In the anthelmintic efficiency assay treatment with 44 mg kg-1 and 88 mg kg-1 of TBZ removed 82 and 96% respectively of the total Ostertagia burden (adults and larvae) from the “nil” strain and 30 and 75% respectively from the “planned” strain. The same dose rates against the “regular” and “tracer” strains and additional rates of 132 or 176 mg kg-1 against the “tracer” strain failed to reduce the Ostertagia burden significantly. Intestinal Trichostrongylus spp from all isolates were fully susceptible to TBZ at 44 mg kg-1. Levamisole at 7.0 mg kg-1 was highly effective (99% reduction) against the “tracer” strain of Ostertagia.     

The epidemiology of nematode and fluke infections in cattle in the Red River Delta in Vietnam

Over a period of 13 months, faecal samples were collected monthly from approximately 45 cattle over 3 months of age. Additionally, 74 calves of 1-2 months were sampled to determine the presence of Toxocara vitulorum eggs. Individual egg counts and infective strongyle larvae from pooled faecal samples were examined. Post-mortem worm counts were carried out on six groups of tracer calves (n=12) that had been kept for 4 weeks on pasture in and around the village studied. The following helminths were identified: T. vitulorum, Cooperia punctata, C. pectinata, C. oncophora, Oesophagostomum radiatum, Trichostrongylus axei, T. colubriformis, Haemonchus spp., Fasciola spp. and Paramphistomum spp. In 8% of the samples collected from young calves, individual egg counts for T. vitulorum were found indicative for pathogenic worm burdens. Strongyle egg counts and worm counts indicated that transmission is low without a distinct seasonality. In animals of 3-9 months old, a strongyle egg count peak can be demonstrated which at a higher age steadily and significantly decreased. In faecal cultures Cooperia spp. were most prominent in all age groups throughout the year with the exception of the period September-November when Haemonchus spp. and Oesophagostomum spp. were most prevalent. Fasciola spp. eggs were found in 22% of the collected faecal samples and the egg counts were low indicating that the intensity of Fasciola spp. infection is mild. Based on the present data, regular anthelmintic treatments seem not to be justified, except for a single treatment at the age of 2 weeks against toxocariosis.     

Efficacy of milbemycin oxime against fourth-stage larvae and adults of Ancylostoma tubaeforme in experimentally infected cats

The efficacy of milbemycin oxime against fourth-stage (L4) larvae and adults of Ancylostoma tubaeforme was investigated in a trial involving 24 young domestic shorthair cats. The animals were inoculated with approximately 300 infective stage three (L3) larvae and divided into three groups. After 12 days, eight cats (group 1) were treated with medicated tablets containing 4 mg milbemycin and 10 mg praziquantel to test the efficacy against L4 larvae; eight cats in group 2 were treated with the same tablets after 33 days to test the efficacy against adult worms; and eight cats in group 3 were treated with a placebo tablet. Faecal egg counts were determined periodically in each cat and after 40 or 41 days the number of worms in each animal was determined postmortem. The egg count reduction was determined by comparing the geometric mean numbers of eggs per gram of faeces in the placebo and medicated groups, and the worm reduction by comparing the geometric mean numbers of worms. The egg count reduction was more than 99 per cent in both treated groups, while the number of worms in groups 1 and 2 were reduced by 94.7 per cent and 99.2 per cent, respectively.     

Anthelmintic Activity of Extracts of Spondias mombin Against Gastrointestinal Nematodes of Sheep: Studies In Vitro and In Vivo

This study was carried out to validate the efficacy of Spondias mombin, used locally as an anthelmintic, and to standardize the effective dose of the plant extract required for worm control in livestock. In vitro and in vivo studies were conducted to determine the direct anthelmintic effect of ethanolic and aqueous extracts of S. mombin towards different ovine gastrointestinal nematodes. A larval development assay (LDA) was used to investigate the in vitro effect of extracts on strongyle larvae. Another study was conducted in vivo to evaluate the therapeutic efficacy of the extracts administered orally at dose rates of 125, 250, 500 mg/kg to sheep naturally infected with gastrointestinal nematodes. Twenty sheep were selected on the basis of positive faecal egg counts (750 epg). The sheep were allocated randomly to a non-medicated control group (A) or to groups given 125 mg/kg (B), 250 mg/kg (C) or 500 mg/kg (D) of extract, respectively. Sheep in groups B-D were given extracts orally on two days. Individual faecal egg counts were performed on days 0, 3, 6, 9 and 12. The presence of S. mombin extracts in in vitro cultures of larvae decreased the survival of L3 larvae. The LC50 of the aqueous extract of S. mombin was 0.907 mg/ml, while the LC50 of the ethanolic extract was 0.456 mg/ml. This difference in LC50 was statistically significant (p > 0.05). The mean percentage faecal egg reduction of sheep drenched with 500 mg/kg S. mombin extracts was 15.0%, 27.5%, 65.0%, 65.0%, 100.0% against Haenmonchus spp., Trichostrongylus spp., Oesophagostomunm spp., Strongyloides spp. and Trichuris spp. respectively, on day 12. Extracts of S. mombin could find application in the control of helminths in livestock.     

STUDIES ON NEMATODE INFECTIONS OF BEEF CATTLE IN NEW SOUTH WALES

The occurrence and seasonal trends of nematode parasite infections in beef cattle on the Tablelands and North Coast regions of New South Wales are described, based on worm counts from 627 spring-born steers slaughtered at 2-monthly intervals from 6 to 24 months of age. The predominant parasites were Ostertagia ostertagi, Trichostrongylus axei and Cooperia spp. Large burdens of adult Ostertagia were seen in 12-month-old animals in late winter and early spring, and later in 18- to 20-month-old cattle in the following late summer and autumn. These infections often resulted in outbreaks of clinical parasitism. Massive numbers of inhibited early fourth stage larvae (EL4) also accumulated in the yearlings during their first spring, reached peaks in mid-summer and then declined. The possibility of their resumption of development to mature worms in the late summer and autumn period is discussed. Adult T. axei showed a similar seasonal trend to Ostertagia and may have increased the severity of outbreaks of clinical disease. Cooperia populations of EL4 and adult worms were highest in weaners during winter, but lower numbers thereafter indicated a strong resistance to re-infection. In addition, Haemonchus placei occurred frequently on the North Coast both as EL4 and adults in cattle of all ages up to 20 months. Of the other cattle nematodes, Oesophagostomum radiatum and Trichuris spp occurred in low numbers, mainly in weaners. Bunstomum phlebotomum and H. contortus occurred sporadically on the North Coast and Tablelands respectively. Intestinal Trichostronglyus spp, Oesophagostomum venulosum and Dictyocaulus viviparus were seen occasionally and Nematodirus spp were not seen. There was a poor relationship between worm counts and faecal egg counts. Cooperia spp dominated the egg counts, while those for other genera were generally low and did not reflect the relative abundance or seasonal changes in worm numbers.     

Prevalence of gastro-intestinal nematode infection in the dromedary camel (Camelus dromedarius) in the Butana plains, Sudan.

The prevalence and intensity of gastro-intestinal nematode infection in their relation to season and rainfall were investigated from 429 female dromedary camels at Tambul market in the Butana plains (Sudan), during 1985-1986. The investigation revealed a similar seasonal pattern in the prevalence as well as the intensity of egg output. The seasonality is mainly brought about by Haemonchus spp. and Impalaia spp. while Trichostrongylus spp. seem to be present as adults throughout the year. There is a good correlation between high egg counts and rainfall ensuring optimal development of preparasitic stages.     

Anthelmintic resistance survey in New Zealand

The prevalence and level of thiabendazole resistance of sheep nematodes in the North Island of New Zealand was investigated by means of an in vitro egg-hatch technique; samples from sheep on 52 properties in six country areas were examined. Resistance of Haemonchus contortus and Trichostrongylus spp. was identified on the basis of egg hatch in 0.1 ppm thiabendazole. Evidence of resistance was obtained on 11(21.2%) of the properties. LD 50's and resistance ratios were calculated for the resistant nematode populations found.