Control of parasitic gastroenteritis in goats.
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The pattern of infection with gastro-intestinal nematodes in young fattening lambs at pasture.
The pattern of infection with gastrointestinal nematodes in young fattening lambs was determined during the period 1965-69 in 10 counties of the UK. On 25 farms with a history Nematodirus disease, 193 lambs were killed, mostly in pairs, at intervals of three weeks from the end of April to mid-July. In three of the seasons similar studies were extended to mid-September on 33 farms which had a history of parasitic gastroenteritis. Worms were counted 361 parasitic gastroenteritis. Worms were counted in 361 lambs killed at intervals of four weeks. The degree of infection and incidence of different genera covering the same period were identical in both series. The division into Nematodirus and parasitic gastroenteritis farms proved artificial and the results were combined to obtain an overall picture based on average worm burdens during weekly periods from the last week in April to the second week in September. An average total of 2500 worms was present in four-week-old lambs at the end of April and this rose steadily to a peak of 10, 000 during the first week in June. A gradual fall to 5500 in mid-July was followed by a rapid rise which had reached 22, 000 at the end of observations in mid-September. The first wave of infection up to mid-July consisted almost entirely of Nematodirus and Ostertagia in the approximate proportions 3;1, 2:1 and 1-5:1 midway through the months of May, June and July respectively. The second rise from mid-July onwards consisted principally of Ostertagia and Trichostrongylus. Nematodirus worm numbers remained at a lower level while a few Cooperia and Haemonchus had appeared. Unidentified third and fourth stage larvae in the abomasum and small intestine reflected the prevalence of Ostertagia and Nematodirus respectively. The significance of this infection pattern, which was common to all geopgraphical areas, in relation to the epidemiology of parasitic infections in lambs is discussed.
Abomasum↗
Seasonal variations in the gastro-intestinal nematode populations of Scottish hil sheep.
In each of two consecutive years, groups of breeding ewes were removed from a hill farm in the west of Scotland on four occasions, namely late pregnancy, early lactation, autumn and early winter. At slaughter the major nematode genus present in the alimentary tract was Ostertagia, with O circumcincta the predominant species but three species previously found in Scottish hill sheep, Bunostomum trigonocephalum, Strongyloides papillosis and Chabertia ovina were absent. An absolute increase in total nematode burden and faecal egg count was apparent in the ewes commencing in late pregnancy, reaching a maximum during lactation and falling again in autumn and early winter. This peri-parturient increase in the nematode population could not be solely attributed to the maturation of previously inhibited larval stages but was primarily the result of the development of recently ingested infection; the latter situation thought to be due to a temporary relaxation of immunological response by the ewe at parturition or early lactation. Serum pepsinogen values in ewes remained elevated throughout the grazing season and were always higher than those of their lambs, suggesting that the ewe, although allowing few parasites to become established, was under considerable challenge in the autumn. The worm burdens of the lambs were always low in autumn and early winter with Ostertagia spp being the major genus present during the autumn and Trichostrongylus spp being the predominant genus during the early winter.
Abomasum↗
The anthelmintic efficacy of fenbendazole against a mixed nematode infection in sheep.
Fenbendazole (methyl-5-(phenylthio)-2-benzimidazole carbamate) at dose rates of 5 mg/kg and above was 100 per cent effective in eliminating a naturally acquired Dictyocaulus filaria infection in sheep. The drug was 100 per cent effective in eliminating concurrent infections of adult Trichostrongylus axei, Haemonchus contortus, Haemonchus placei, Ostertagia circumcincta, Ostertagia ostertagii, Cooperia oncophora, Cooperia mcmasterii, Nematodirus spathiger, Neumatodirus filcollis, Oesophagostomum venulosum and Chabertia ovina. Fenbendazole was 93 per cent and 97 per cent effective at doses of 5 and 10 mg/kg respectively in removing infection with adult T colubriformis, and post-treatment worm-egg production was completely suppressed in surviving female worms. No adverse side-effects were observed in treated sheep at either of the two dose rates used.
Animals↗
Age group interaction of Haemonchus contortus in premunized lambs.
Lambs premunized with a relatively less pathogenic (RLP) isolate of Haemonchus contortus were challenge exposed each day with 500 3rd-stage larvae (L3) of a normally pathogenic isolate of the same worm, starting on day 9 of the premunition-induced infection. In 6-month-old lambs, there was a fourfold decrease in egg production by the premunizing RLP isolate with challenge exposure compared with egg production in lambs given only the premunizing RLP isolate and not challenge exposed. Premunized lambs were able to carry larger worm burdens with less hemoglobin loss than were nonpremunized challenge-exposed control lambs. Although challenge exposure had affected parasitic egg production by the 9-day-old premunizing RLP worms, the same young infective isolates were able to survive and protect lambs against the additional parasitism.
Abomasum↗
The use of disophenol in studies of the pathogenicity of the arrested fourth-stage larvae of Haemonchus contortus in the sheep.
Disphenol was administered to sheep infected with Haemonchus contortus in order to prevent the development of populations of adult worms, and studies were made of the pathogenicity of the arrested fourth-stage larvae which remained. The treated sheep showed elevated plasma pepsinogen and abomasal pH, predominantly negative dry-matter balance, and evidence of greater fluid loss, including plasma, into the gastro-intestinal tract. It was concluded that arrested larvae may cause damage to the abomasal mucosa.
Abomasum↗
Clinical evaluation of anaemia in sheep: early trials.
Trials were conducted on a farm in Mpumalanga Province in South Africa to test the possibility of grading the colour of the ocular mucous membranes of sheep as an indication of the extent to which the animals are affected by Haemonchus contortus infection. The range of observed colour shades were classified into five categories, from red, through red-pink, pink and pink-white to white. Over a period of 125 days routine drenching of a flock of 388 sheep on irrigated kikuyu (Pennisetum clandestinum) pasture was terminated. During this time the animals were examined at practically weekly intervals and haematocrit determinations done for all the sheep with pale conjunctivae. Only those sheep having a haematocrit of 15% or lower were treated. Compared to a previous drenching tempo of close to every 3 weeks during the Haemonchus season on the farm, drenching was reduced by approximately 90%, as 70% of the sheep did not require salvage drenching and only 10% of the flock had to be given more than one salvage treatment. At the time of the trial the five clinical classifications were not related to predetermined haematocrit categories. However, when compared to categories that were set in later trials, 94% of the clinical estimates in the present trial were either in the correct haematocrit category, or, if not, the sheep were probably not disadvantaged by the errors. In 2.6% of cases the incorrect estimate may have placed the sheep concerned in jeopardy, as the haematocrit values were so low that salvage drenching was required, while the sheep were not regarded as anaemic. Changes in the mean haematocrit values of drenched and undrenched sheep were mirrored reciprocally by the changes in clinical colour estimates. Lactating ewes were by far the most susceptible class of sheep, as only 44.6% of them were able to manage without drenching, compared to 83% of dry, and 70.6% of pregnant ewes. Correlations between the haematocrits and clinical estimates were highly significant, although the associations were not high enough to give reasonable surety that the haematocrit values of individual animals could be predicted with confidence from their clinical classifications. Exceptionally large numbers of worms were recovered from seven of the 14 sheep that were culled because of age at the end of the trial, but these were reflected neither in their faecal worm egg counts, nor, with one exception only, in clinical signs.
Anemia↗
Potency of three Haemonchus contortus antigens in the diagnosis of ovine haemonchosis.
One hundred faecal specimens and corresponding blood samples were evaluated for Haemonchus contortus infection in sheep by ELISA utilizing somatic, circulating and coproantigens. Results proved that coproantigen was more potent than the others in diagnosis of sheep haemonchosis. SDS-polyacrylamide gel electrophoresis demonstrated that the three antigens are structurally related. Immunoblot analysis revealed that somatic antigen contained 6 polypeptides of molecular weights 234, 205, 178, 83, 48 and 14 kDa, while, coproantigen showed 4 immunogenic polypeptides of 234, 205, 85 and 45 kDa. In circulating antigen only 2 polypeptides of molecular weights 165 and 99 kDa were immunoreactive. The potency of coproantigen may be attributed partially to one polypeptide of molecular weight 45 kDa. This low molecular weight polypeptide was only expressed in coproantigen as an immunogen, probably increases the immunogenicity, and may have potential diagnostic and protective values.
Animals↗
Efficacy of Fenbendazole against gastrointestinal parasites of sheep.
Lambs severely parasitized by Haemonchus, Ostertagia, Trichostrongylus, Cooperia, Oesophagostomum, and Nematodirus were treated with fenbendazole (methyl 5-(phenylthio)-2-benzimidazolecarbamate) given at 3 dose levels: 3.5, 5.0, and 7.5 mg/kg of body weight. Efficacies against these genera, except Haemonchus and Nematodirus, were 100% at the 3 dose levels. Efficacies for the 3 doses against Haemonchus were 93.4, 95.3, and 99.8%, respectively, and against Nematodirus, 99.5, 99.6, and 100%. Efficacies for the doses against Trichuris were 69.1, 83.6, and 98.2%. Toxicosis due to the durg was not seen in these lambs, although they were severely debilitated.
Animals↗
A survey on anthelmintic resistance in nematode parasites of sheep in Lusaka, Zambia.
While surveys in Southern Africa indicate anthelmintic resistance of gastrointestinal nematodes to be common in small ruminants in South Africa, Kenya and Zimbabwe there have been no reports of resistance in Zambia. The objective of this study was to determine whether anthelmintic resistance occurs in Zambia, and to obtain information on nematode control practices in the country. During the rainy season six commercial sheep farms were selected in and around Lusaka and Chisamba. Worm control practices were gauged by means of a questionnaire, and the Faecal Egg Count Reduction Test was performed for assessing anthelmintic efficacy of albendazole, levamisole and ivermectin. On all farms anthelmintic treatment was the only approach used to control nematode infections. Frequency of treatment varied from twice a year to every 6 weeks and drugs of different anthelmintic groups were alternated within the same year. There was a wide range in faecal egg counts of individual sheep before treatment, with some individual counts of up to 87000. Larval identification showed that Haemonchus was almost the only genus recovered from the faecal cultures before and after treatment. Albendazole resistance was found on five of the six farms. On each of the four farms where ivermectin gave less than 95% reduction in egg counts, there was resistance to albendazole as well. Levamisole showed an efficacy of 95% or higher on all six farms.
Albendazole↗
The resistance of a field strain of Haemonchus contortus to five benzimidazole anthelmintics in current use.
Using artificially infected sheep, the response of a laboratory strain of Haemonchus contortus, which had not been subjected to anthelmintics for three years, was compared with that exhibited by a parbendazole resistant field strain following treatment with each of seven anthelmintics, the laboratory strain proved fully susceptable to thiabendazole, parbendazole, cambendazole, mebendazole, fenbandazole, levamisole and haloxon, in contrast to the field strain which showed a moderate to marked resistance to all five benzimidazoles, but was fully susceptible to levamisole and haloxon.
Animals↗
Helminth parasitisms among intermingling insular populations of white-tailed deer, feral cattle, and feral swine.
Helminth infections among free-ranging, intermingling populations of white-tailed deer (Odocoileus virginianus), cattle (Bos taurus), and swine (Sus scrofa) on an island off the Georgia coast were studied. Of 39 species of helminths collected, 19 were found in deer, 17 in cattle, and 13 in swine. Of 28 species of helminths recovered from ruminants, 8, viz, Capillaria bovis, Cooperia punctata, Dictyocaulus viviparus, Gongylonema pulchrum, G verrucosum, Haemonchus contortus, Moniezia benedeni, and Trichostrongylus axei, occurred in both deer and cattle. Common liver flukes (Fasciola hepatica) infected cattle and swine but not deer. Only 1 helminth, G pulchrum, infected deer, cattle, and swine. The findings suggested that helminths harbored by the host species are distinct, with little exchange occurring.
Animals↗
Occurrence of gastrointestinal parasites in Georgia cattle.
A survey of gastrointestinal nematodes in Georgia cattle was conducted from 1968 through 1973 from actual worm counts from viscera of 145 slaughtered beef cattle or from egg counts made from fecal samples from 3,273 beef and 100 dairy cattle. Beef cattle were grouped as calves, yearlings, and cows. Dairy cattle were grouped as calves, replacement heifers, and cows. Results of fecal examinations positive; 99.5, 99.3, 99.6, and 41.2% of the calves, yearlings, drylot calves, and cows, respectively, were infected with nematodes. Seventy-four percent of the eggs counted were of the Cooperia-Ostertagia - Trichostrongylus complex (C-O-T) and 21% were of the Haemonchus-Oesophagostomum complex (H-O). Sixty-nine percent of the infective larvae recovered from coprocultures made from composite samples were of Ostertagia ostertagi. Moniezia (tapeworm) eggs were seen in 16% of all the samples, more predominantly in the calves (24%) and less in the cows (smaller than 1%). Oocysts of Eimeria spp were detected in 61% of the cattle, more predominantly in younger cattle. All cattle necropsied were infected with O ostertagi. Other nematodes present, in order of decreasing frequency, were Trichostrongylus axei (97%), Haemonchus placei (66%), Cooperia punctata (63%), Cooperia oncophora (61%), Oesophagostomum radiatum (61%), Bunostomum phlebotomum (55%), Trichostrongylus colubriformis (36%), Cooperia pectinata (28%), Trichuris spp (17%), Nematodirus spathiger (9%), and Capillaria bovis (4%). Tapeworms were also recovered from 19% of the cattle at necropsy. Seventy-eight percent of the dairy cattle were positive; 98% of the calves, 80% of the heifers, and 58% of the cows. Cooperia-Ostertagia-Trichostrongylus eggs were detected in 78% and H-O eggs in 38% of the cattle. Eimeria oocysts were detected in 71% of all the dairy cattle, and Moniezia eggs were in 10% of the calves and 7% of the heifers.
Animals↗
Relationship of pasture rotation to acquisition of gastrointestinal nematodes by sheep.
In a study of the relationship between pasture rotation in Illinois and acquisition of nematodes (mostly Haemonchus contortus) and body weight gains by lambs grazing with their ewes, 2 pasture rotation systems were tested. (1) Lambs and ewes were rotated through a series of 12 alfalfa-bromegrass-lespedeza pastures, each pasture being grazed for 3 to 4 days and rested for 5.5 weeks; 4 complete rotations were done during a 168-day grazing season. (2) Lambs and ewes were moved every 2 days, and 3 complete rotations of 50, 42, and 54 days, respectively, were done during the 146-day grazing season. The lambs under rotation had more nematodes and gained less weight than nonrotated control lambs, although rotation increased the amount of pasturage. Rotation is not recommended to control nematode parasitism of sheep in Illinois.
Animals↗
[Changes in the serum proteins in lambs experimentally infected with Haemonches contortus].
Infected were experimentally eight lambs with larvae of Haemonchus contortus. The test lambs were divided into two groups and were given each, by groups, 2500 and 5000 H. contortus larvae. Prior to infection and on the 10th, 20th, 30th, 40th and 50th day following it electrophoretic studies on the blood serum were performed. Results showed that certain quantitative changes in the protein fractions took place. They consist in the drop of the albumin and the rise of the globulin fractions.
Animals↗
Nematode parasitism in cattle.
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Age Factors↗
The efficacy of thiabendazole against the arrested larvae of some Trichostrongylidae and Chabertia ovina in sheep.
The activity of thiabendazole at 100 mg/kg was tested against the arrested larvae of Ostertagia spp, Haemonchus contortus, Trichostrongylus axei, Nematodirus spp and Chabertia ovina in natural infections, in 10-month-old lambs. The result, assessed by means of worm counts, showed the treatment to be very effective.
Animals↗
Freezing of sheep faeces invalidates Haemonchus contortus faecal egg counts by the McMaster technique.
Faecal pellets from a sheep that was artificially infected with a monoculture of Haemonchus contortus were collected over a 2-h period in the morning. In the laboratory the faeces were thoroughly mixed by hand and 48 by 1 g aliquots of the pellets were sealed in plastic bags, from which the air had gently been expressed. The faecal worm egg count of the sheep was about 14,000 g(-1). Varying numbers of the bags were either processed for faecal worm egg counting (FEC) by the McMaster technique on day 0, or were stored at one of the following temperatures: about 4 degrees C, -10 degrees C or -170 degrees C before processing. The faecal aliquots that were frozen were thawed at room temperature after having been frozen for either 2 h or 7 days, and processing of aliquots maintained at 4 degrees C proceeded shortly after the samples had been removed from the refrigerator. A dramatic reduction in egg numbers was found in all the aliquots that were frozen at -170 degrees C before faecal worm egg counts were done, as well as in those frozen for 7 days at about -10 degrees C. Numerous empty, or partially empty, egg shells were observed when performing the counts in faeces that had been frozen. In contrast, there was no significant reduction in the numbers of eggs in aliquots maintained for 7 days in a refrigerator at +/- 4 degrees C before examination, when compared with others examined shortly after collection of the faeces. Since H. contortus eggs in faeces are damaged by freezing, some methods that can be used for short term preservation are outlined. It is concluded that all nematode egg counts from cryopreserved faeces (whether in a freezer at -10 degrees C or in liquid nitrogen) should possibly be regarded as being inaccurate, unless the contrary can be demonstrated for different worm genera. However, exceptions are expected for the more rugged ova, such as those of the ascarids and Trichuris spp.
Animals↗