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1.
Strongyle infections in ponies. II. Reinfection of treated animals.   总被引：1，自引：1，他引：0       下载免费PDF全文
Five of seven ponies whose strongyle worm burdens had previously been removed or markedly reduced by repeated thiabendazole treatments were reinfected with doses ranging from 100,000 to 500,000 small strongyle infective larvae. Reinfection of ponies resulted in the development of clinical signs characterized by abnormal feces, marked loss of weight and delayed shedding of winter hair coats. An abrupt increase in circulating eosinophils occurred during the first three weeks following reinfection. Patent infections developed in all ponies with worm eggs appearing in the feces from 12 to 15 weeks after receiving infective larvae. Worm egg outputs followed a cyclic pattern with approximately four to five peaks in egg output per year. There was an abrupt drop in the high worm egg counts in two untreated ponies approximately two and a half years after reinfection. No worms were recovered in the feces of these animals when they were subsequently treated, suggesting that a depletion in the number of inhibited larvae present in these ponies might have occurred.  相似文献   

2.
Oxibendazole (OBZ; 10 mg/kg of body weight) was administered to ponies at 8-week intervals to control strongylosis in a breeding band of Shetland-type ponies (n = 29 to 50) from October 1978 through September 1984. A similar use of cambendazole (CBZ; 20 mg/kg of body weight) in this band of ponies during the preceding 4-year period resulted in the survival of a CBZ-resistant population (S) of small strongyles. Effectiveness of OBZ treatments was monitored by pre- and posttreatment counts of the number of strongyle eggs per gram of feces (epg) and of the number of strongyle larvae per gram of feces (lpg). For the first 4 years of the 6-year period, epg and lpg counts were determined for 3 to 5 of the OBZ treatments; during the last 2 years, counts were determined for each treatment. For the 1st year, the mean reduction in epg was 96%. During the 2nd and 3rd years, mean reductions in epg were 80% and 81%, respectively. For the 4th and 5th years, mean reductions in epg were 69% and 43%, respectively. For the 6th year, the mean reduction in epg was 37%. Statistical analyses of the epg data, using the linear plateau method, indicated a significant increase in residual (surviving) strongyle infections after the periodic OBZ treatments, with a mean annual increase in survival of 10.3% for the 6 years. Changes in lpg were variable, but an overall loss of effectiveness of the OBZ treatments was evident. Only infective larvae of small strongyles were observed in the cultures; larvae of 2 species of large strongyles, Strongylus vulgaris and Strongylus edentatus, were conspicuously absent.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

3.
To determine the efficacy of a formulation of milbemycins in treating patent infection with Toxocara canis, 8 male and 7 female, 10-week-old, ascarid-free Beagles each were given 125 embryonated eggs of T canis. All dogs developed patent infection within 56 days. On post-infection day 70, the dogs were assigned to 1 of 3 groups of 5 dogs each; members of 1 group were given a placebo, while dogs of the other 2 groups were given either 5.68 or 34.08 mg of the milbemycin formulation, respectively. In both groups of dogs given the drug, the number of eggs passed per gram of feces decreased precipitously. However, a few eggs still were found in the feces of several dogs of each group on the day of necropsy (postinfection day 75). Worms or fragments of worms were passed by the treated dogs from the day of treatment until the day on which necropsy was performed; however, most worms were passed during the first 2 days after treatment. At necropsy, only dogs of the control group were found to harbor adult T canis.  相似文献   

4.
Two groups of 21 mixed-breed heifers were wintered on separate permanent pastures. Each heifer from one group was administered a sustained-release morantel bolus on October 7 (day 0), and the other group remained as untreated controls. Body weights were determined and fecal samples were taken at 28-day intervals. At the onset of the trail and at every 56 days, 6 heifers were removed from each group for slaughter to determine the developmental stages and the number of gastrointestinal nematodes. In addition, 3 tracer calves that were free of gastrointestinal nematodes were released on each pasture for 28 days at the beginning of the trail and after the last experimental-group calves had been removed. The 6 calves slaughtered on day 0 of the trail had a mean of 5,544 gastrointestinal nematodes. Tracer calves released on day 0 and removed on day 28 of the trial acquired 31,143 and 30,530 gastrointestinal nematodes from the pastures containing the treated and control heifers, respectively. Throughout the trial, the number of nematodes in the control calves increased at each sampling date (mean, 126,168 worms), whereas the mean number of worms in the treated heifers was 45,458. Tracer calves placed in the pastures after the 168-day trail acquired significantly more worms (9,632 vs 2,899; P less than 0.05) from grazing the pastures with control heifers than from grazing the pastures with treated heifers. Counts of eggs per gram of feces were significantly different (P less than 0.01) between the 2 groups from day 28 through day 112.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
A group of seven ponies naturally infected with large numbers of small strongyles and raised under conditions to minimize reinfection were treated periodically over a three year span with thiabendazole at the rate of 44 mg/kg body weight. Based on the absence of worm eggs in the feces following each treatment, thiabendazole removed the adult strongyles present with a new population subsequently developing by maturation of inhibited larvae. It took as many as four or five treatments to eliminate or reduce significantly the worm burdens present in the ponies under the conditions of this study. Strongyle eggs started to reappear in the feces about six weeks after treatment and following the first treatment the mean egg counts rose to the pretreatment level. On successive treatments the interval for worm eggs to appear in the feces lengthened and mean egg counts never rose quite as high as immediate pretreatment levels. Hematological changes were not marked, although a small steady increase in the mean hemoglobin values and an equivalent small decrease in the mean eosinophil counts occurred in all ponies following each successive treatment. The study supports the rationale of regular anthelmintic treatment of horses in that even in the absence of reinfection, new burdens of adult worms develop following treatment.  相似文献   

6.
Twenty-six mixed-breed (14 males, 12 females) dogs were used in a double-blind study to evaluate the effect of milbemycin oxime against naturally acquired infection with Ancylostoma caninum. Dogs were ranked and paired, on the basis of number of hookworm eggs/g of feces, and treatment was randomly assigned. Each dog was given either the study drug or placebo (1 tablet/11.4 kg [0.5 mg/kg] of body weight). Eggs per gram of feces enumeration was done on days 3 and 7 after treatment, and dogs were euthanatized on day 7. On day 3, 5 of the 13 dogs in the milbemycin-treated group had hookworm eggs in the feces (results of the McMaster test). In these dogs, mean number of eggs per gram of feces had decreased markedly (from 5,289 to 452) and, by day 7, was 114. At necropsy, 16 A caninum adults were recovered from 2 of the milbemycin-treated dogs. On day 3, 12 of the 13 dogs in the placebo-treated group had hookworm eggs in the feces. Mean number of eggs per gram of feces in these dogs decreased slightly (from 5,243 to 2,646), but did not decrease further by day 7. A mean number of 54.4 A caninum adults was recovered from 12 of the 13 placebo-treated dogs at necropsy. Milbemycin oxime had 97.8% efficacy against A caninum. Results also indicated that milbemycin oxime may be effective against Trichuris vulpis, but not against Dipylidium caninum.  相似文献   

7.
Three of six ponies, 9 and 10 years of age, were each given in excess of 300 000 infective Trichonema larvae experimentally. Although all six ponies had both natural and experimental infections previously, they were virtually parasite-free during the 18-month period immediately preceding experimental reinfection.Appreciable resistance to Trichonema infections was indicated in these mature ponies by a longer prepatency and significantly smaller worm egg outputs than that which occurred when these animals were given comparable infections at a much younger age. Patent infections only developed in two of the three ponies beginning between 17 and 18 weeks post-reinfection with peak egg counts between 200 and 400 eggs per gram (epg) in one and 100 to 150 epg in the other. Within 10 days of reinfection, an abrupt rise in mean circulating eosinophils and an appreciable mean weight loss, which persisted for 2 years, occured in the reinfected but not the control ponies.The findings, particularly of unthriftiness characterized by persistent loss of weight in the reinfected but not the control ponies, demonstrated the pathogenesis of inhibited Trichonema larvae.  相似文献   

8.
The clinical pathology of Schistosoma curassoni infection in sheep and goats was studied for 22 weeks following experimental infection with 7000 and 4000 cercariae, respectively. Excretion of eggs began at week 7 after infection: in goats the numbers increased to 30 to 50 eggs per gram faeces (epg) at weeks 8 to 18, followed by a reduction. In a pregnant goat, epg values increased markedly before and after parturition. The mean faecal egg counts in sheep were lower than in goats, increasing to a maximum level of 30 epg at weeks 16 and 17 after infection. Infected sheep maintained growth rates roughly comparable with controls, whereas infected goats failed to gain as much weight as the controls. Infected goats and sheep produced eosinophil counts of about 3 x 10(3) mm-3, five and eight weeks after infection, respectively. Sheep developed a progressive anaemia from week 11 after infection, in goats blood values remained within normal limits. Differences in serum protein concentration were observed between infected and uninfected goats about nine weeks after infection, but not in sheep. Increased total protein values, hyperglobulinaemia and lowered albumin to globulin ratios were features of infected goats. Serum glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, gamma-glutamyl transferase, total lactate dehydrogenase and bilirubin were not significantly changed. The mean recovery in sheep was 608 worms, in goats 428 worms, but the total tissue egg counts were higher in the latter. Of the total eggs deposited in the goats 92 per cent were found in the liver with 51.5 per cent in the ovine liver. The histopathological changes were studied.  相似文献   

9.
A clinical trial was conducted with 2- to 3-year-old ponies to determine the effectiveness against strongyles of 2.64 mg pyrantel tartrate/kg body weight administered in the daily ration throughout a pasture season in Canada. Ten ponies were given the anthelmintic, and 10 were not treated and served as controls. Each group of ponies was on a separate pasture. The mean strongyle eggs/g of feces for each group, before treatment and turnout to pasture, was greater than 2,200. Thereafter, the mean eggs/g feces for the untreated group remained high (1,405−2,294) and those for the treated group decreased markedly to, and remained at, very low levels (0.2−16.8). Strongyle larval counts for the pasture with the untreated ponies rose to 26,790 larvae/kg dry herbage in August, whereas that for the treated group was 610 larvae/kg dry herbage. At the end of the season, two ponies from each group were isolated for 6 weeks and necropsied. The mean number of strongyles in the untreated and treated ponies was 69,288 and 8,452.5, respectively. In the untreated ponies, 21 species of strongyles were found, and approximately 84% of them were from eight species of cyathostomes. In the treated ponies, 14 species of strongyles were found, and approximately 77% were from one species, Cylicostephanus minutus (52.0%), and immature cythostomes (25%). Adverse reactions were not observed in any of the treated ponies. Pyrantel tartrate was highly effective in significantly reducing the strongyle egg and pasture larval counts and the transmission of strongyles during a pasture season.  相似文献   

10.
捻转血矛线虫重组H11抗原山羊免疫保护性试验   总被引：1，自引：0，他引：1  
以重组H11-1、H11-2及H11-1与H11-2混合物分别免疫山羊后,ELISA检测发现血清抗体均在首次免疫后14 d达到较高水平,在第2次免疫后10 d达到高峰。用10 000只捻转血矛线虫第3期幼虫攻击山羊后,对不同免疫组山羊排出虫卵数、虫卵孵化率和成虫数的统计分析结果表明,免疫组与对照组间差异不显著,但免疫组雌虫数显著少于对照组,这对防治捻转血矛线虫病可能会起一定的作用。  相似文献   

11.
Epidemiology and control of equine strongylosis at Newmarket   总被引：1，自引：0，他引：1  
Seasonal rises in mean faecal egg output were observed in grazing ponies in spring (578 eggs per gram) and in summer (930 epg) on 30 April and 2 September, respectively, in untreated ponies. Pasture infectivity reached a peak of 18,486 third stage larvae (L3)/kg on 17 September, two weeks after peak egg counts, coincidental with abundant September rainfall (103.0 mm). Differentiation of infective larvae from pasture showed the cyathostomes (small strongyles) to be predominant, but Trichostrongylus axei assumed major importance from late August to October. The large strongyles were rarely detected: Strongylus vulgaris was found only once and S edentatus only twice. The most effective parasite prophylaxis was achieved by twice weekly removal of faeces. In this group, concentrations of infective L3 on pasture reached a maximum of 1000 L3/kg, compared to 18,486 L3/kg for a control group and 4850 to 10,210 L3/kg for anthelmintic treatment groups. The removal of faeces increased the grazing area by about 50 per cent, by eliminating the characteristic separation of horse pasture into roughs and lawns. Spring and summer anthelmintic treatments of mature ponies with oxibendazole were effective in reducing the late season rise in pasture infectivity to 4850 L3/kg, but treatment of young ponies (mainly yearlings) with ivermectin every eight weeks or oxibendazole every four weeks resulted in pasture infectivity as high as 10,000 L3/kg. There was evidence of cyathostome resistance to benzimidazole drugs.  相似文献   

12.
Observations were completed over an 18-year period (1966 through 1983) in Thoroughbred mares (15/year) and yearlings (11 to 24/year) on a farm where benzimidazole-resistant small strongyles had emerged previously (1962 to 1965). This farm was operated as a closed, nonboarding type, which included a racing stable for its home-bred foals. At 2-week intervals, counts of worm eggs per gram of feces (EPG) and larvae per gram of feces were done to monitor strongyle infections and efficacies of bimonthly (every 8 weeks) antiparasitic treatments that were administered by stomach tube or were fed (dichlorvos pellets) to 1 group of yearlings during a 7-year period (1970 through 1976). The study included several drugs or mixtures, including thiabendazole (TBZ), phenothiazine (PTZ) + piperazine (PPZ)-carbon disulfide (CS2) complex, PTZ + PPZ + trichlorfon (TCF), dichlorvos, and pyrantel pamoate. These were used selectively in treated subgroups (usually 3/year) of mares and yearlings. The horses in drug treatment subgroups grazed together on common pastures; thus, efficacy comparisons between drugs were limited or nullified. However, annual mean EPG and larvae per gram of feces counts of mares and yearlings tended to increase over time, and for the yearlings treated with TBZ + PPZ and PTZ + PPZ-CS2, the buildup of these mean counts was statistically significant (P less than 0.05 for regression coefficients).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

13.
绵羊与牛片形吸虫病的粪便检测新技术   总被引：11，自引：2，他引：9  
本文应用廖党金 (1 996)的方法 [9] ,并对粪便的不同稀释度和采样量进行处理来检测绵羊和牛片形吸虫病。选 2只绵羊 ,每羊分别称取 1 g、3g、5g、8g、1 1 g和 1 4g粪便样品 ,每个样品沉淀液分别做 5～ 1 0 m L/g的稀释 ;选 3头黄牛 ,每牛分别称取 3个 1 0 g粪便样品 ,样品沉淀液分别做 3～5m L/g、5～ 7m L /g和 5～ 8m L /g稀释度 ,然后计数其片形吸虫虫卵 ,结果表明每 g羊粪便沉淀液稀释 5～ 1 0 m L和每 g牛粪便沉淀液稀释 3～ 7m L较佳。对片形吸虫虫卵在牛和羊粪便中分布的均匀性测定 :在 6只绵羊 ,从每只绵羊一次排出粪便的 6个不同部位各取一个 2 g重的小样品 ,分别对这 6个小样品处理、计片形吸虫虫卵数 ,求出其 EPG值 ;在 4头黄牛 ,从每头黄牛一次排出的粪便的 5个不同部位各取 1 0 g重的小样品 ,分别对这 5个小样品处理、计片形吸虫虫卵数 ,求出其 EPG值。然后用数学方法分别处理其 EPG值 ,结果表明用本检测方法检查绵羊片形吸虫病所需的粪便采样量每只羊应在 4.7g以上 ,检查牛片形吸虫病所需的粪便采样量每头牛应在 2 7.5g以上  相似文献   

14.
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.  相似文献   

15.
One hundred-twenty horses and ponies ranging in age from 142 days to 23 years were used to assess the efficacy and acceptability of ivermectin liquid for horses when given as an oral drench or by nasogastric intubation. Prior to treatment, animals in this study were found to have eggs in the feces of one or more of the following: strongyle type, Parascaris equorum, and Strongyloides westeri. While egg parasite per gram (EPG) numbers from 30 untreated controls remained consistently positive over a 14 day period, parasite EPG numbers from animals treated on Day 0 were reduced to 0 by day 14 as determined by a modified McMaster technique.  相似文献   

16.
The efficacy of a beef-based, chewable formulation of ivermectin against a mixed infection of Ancylostoma braziliense and A tubaeforme was determined in cats. Ivermectin administered orally at approximately 24 micrograms/kg of body weight was 92.8% effective against adult A braziliense and 90.7% effective against adult A tubaeforme. The number of eggs per gram of feces had decreased 98.1% by 7 days after treatment. Clinical signs of hookworm disease also decreased after treatment. Location of adult parasites within the small intestine, percentage of infecting larvae that developed to the adult stage, and egg size in cats with infections of A braziliense and A tubaeforme were similar to those reported for cats with separate infections of either species.  相似文献   

17.
Immunologic and hematologic responses were examined in 4 ponies with experimentally induced Strongylus vulgaris infection and in 5 helminth-free ponies. Two ponies were inoculated with 200 larvae and 2 were inoculated with 700 larvae of S vulgaris and then were reinoculated with the same numbers of larvae 34 weeks later. Initial response of the ponies inoculated with S vulgaris was S vulgaris antigen-induced lymphocyte response that developed 1.5 to 3 weeks after inoculation and did not persist. Development of antigen-reactive lymphocytes was followed sequentially by a biphasic complement-fixing antibody response, then biphasic eosinophilia. Antibody titer to S vulgaris antigen was higher in ponies inoculated with 700 larvae, compared with that in ponies given 200 larvae of S vulgaris. Also, the second peak in antibody titer and in absolute number of eosinophils was observed earlier in ponies inoculated with 700 larvae, compared with ponies inoculated with 200 S vulgaris larvae, and subsided before or from about 24 weeks after inoculation. The prepatent period for S vulgaris infection was 24 to 25 weeks. After reinoculation with S vulgaris, a degree of increased lymphocyte responsiveness was apparent but, by 17 weeks after reinoculation, only the primary peak in the absolute number of eosinophils indicated an anamnestic response. Essentially, antibody was not detectable after reinoculation.  相似文献   

18.
Elk infected with the meningeal worm, Parelaphostrongylus tenuis (Protostrongylidae), do not consistently excrete larvae in feces, making the current method of diagnosing live animals using the Baermann fecal technique unreliable. Serological diagnosis could prove more useful in diagnosing field-infected animals but depends on the identification and availability of good quality antigen. To mimic field infections, 2 elk were inoculated with 6 infective L3 larvae of P. tenuis, and another 2 with 20 L3 larvae. Fecal samples were examined for nematode larvae using the Baermann technique and serum samples taken were tested for anti-P. tenuis antibody with ELISAs by using the excretory-secretory (ES) products of L3, and sonicated adult worms as antigens. One animal passed first-stage larvae in its feces 202 days postinoculation, but passed none thereafter. The remaining 3 inoculated animals did not pass larvae. In contrast to parasite detection, antibodies against larval ES products were detected in all animals starting from 14 to 28 days postinoculation and persisted until the termination of the experiment on day 243 in 2 animals that harbored adult worms. Antibodies against somatic antigens of the adult worm were not detected until day 56 but also persisted until the end of the experiment in the animals with adult worms. In 2 elk that had no adult worms at necropsy, anti-ES antibodies were detected transiently in both, while anti-adult worm antibodies were present transiently in one. These findings confirm the superiority of P. tenuis larval ES products over somatic adult worm antigens as serodiagnostic antigens, as previously observed in studies of infected white-tailed deer, and extend the application of the newly developed ELISA test in diagnosing and monitoring cervids experimentally infected with P. tenuis.  相似文献   

19.
An outbreak of ascaridiasis occurred in 10-wk-old guinea fowl (Numida meleagris) on a commercial farm. Birds had exhibited elevated mortality (11.66%) in the previous week, as well as increased water consumption, weakness, anorexia, and stunted growth. Numerous nematodes, occasionally occluding the intestinal lumen, were present in the jejunum and ileum and were identified as Ascaridia numidae based on microscopic morphology. Ribosomal DNA 18S and 28S D3 sequences of the nematode were deposited into GenBank and found to be most similar to Ascaridia galli and Toxocara vitulorum, respectively; sequences for A. numidae had not been previously reported. Treatment with piperazine sulfate significantly reduced the number of adult worms in the intestines, greatly decreased eggs per gram of feces, relieved clinical signs in the flock, and returned the flock mortality back to expected levels. All findings implicate A. numidae as the cause of elevated mortality in this flock.  相似文献   

20.
A controlled test was done in 30 naturally infected ponies to evaluate the antiparasitic activity of the dienbendazole analog VET 220-S given alone or with trichlorfon (TCF) by nasogastric intubation. Six ponies were nontreated; 6 were given VET 220-S (5.0 mg/kg); 6 were given TCF (40 mg/kg); 6 were given VET 220-S (2.5 mg/kg) and TCF (40 mg/kg); and 6 were given VET 220-S (5.0 mg/kg) and TCF (40 mg/kg). All ponies were euthanatized and necropsied 7 or 8 days after treatment. Draschia megastoma, Oxyuris equi, Strongylus vulgaris, S edentatus, and small strongyles were removed efficaciously by all doses of VET 220-S. Habronema muscae and microfilariae of Onchocerca cervicalis were not removed by VET 220-S or TCF. Gasterophilus intestinalis was 97.9% removed by TCF. Pregnant mares in all groups were not adversely affected by treatment, except for 1 mare that had diarrhea after TCF treatment. Parasite eggs per gram and larval culture data agreed with necropsy data.  相似文献   

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