Mucosal IgA production and lymph cell traffic following prolonged low level infections of Ostertagia circumcincta in sheep

Some aspects of the local immune response to daily challenge with 2000 Ostertagia circumcincta larvae were studied by monitoring changes in the composition of gastric lymph of naive and previously infected sheep. The main changes in the naive group were increases in lymphoblast output and concentrations of pepsinogen whereas lymph albumin values decreased markedly and IgA concentrations were usually unchanged. In contrast, in the previously infected sheep, the continuous challenge stimulated only transient increases in lymphoblast and IgA containing cell traffic whereas lymph IgA and pepsinogen concentrations remained elevated throughout the experiment. By temporarily interrupting the challenge in a second group of previously infected sheep it was shown that elevated IgA and pepsinogen values were maintained only if larval intake was continuous.     

Further studies on the response to transplanted adult Ostertagia ostertagi in calves

Calves infected by surgical transplantation of adult Ostertagia ostertagi had raised levels of plasma pepsinogen and those in which the largest number of worms established also had elevated plasma gastrin concentrations. Despite the elevated plasma pepsinogen values, the abomasal pH of the animals did not change significantly, and there was no significant difference in the percentage establishment of adult parasites in calves previously infected with O ostertagi third stage larvae and those which had been maintained parasite-naive before transplant.     

Forms of bovine pepsinogen in plasma from cattle with three different 'syndromes' of Ostertagia ostertagi infection

Calves infected orally with third stage larvae of Ostertagia ostertagi or infected with adult O ostertagi by direct transplantation into the abomasum had raised plasma pepsinogen activity, as did four-year-old dairy cattle challenged with O ostertagi third stage larvae on five occasions. Using fast protein liquid chromatography two forms of pepsinogen; pepsinogen 1 (PG1) and pepsinogen 2 (PG2) were identified in each of the parasitic infection regimes.     

The distribution of pepsinogen within the abomasa of cattle and sheep infected with Ostertagia spp. and sheep infected with Haemonchus contortus.

The effect of nematode infections on the production of pepsinogen by ruminants was investigated immunohistochemically and biochemically. Abomasal tissues were collected from parasite-naive cattle and sheep, from sheep infected with predominantly Ostertagia circumcincta, sheep infected experimentally with Haemonchus contortus and cattle infected with Ostertagia ostertagi. Pepsinogen was also assayed biochemically in homogenates of fundic mucosae from sheep infected with predominantly O. circumcincta. Infection with Ostertagia spp. parasites was associated mainly with nodular hyperplasia, resulting in increased numbers of cells that produce both pepsinogen and mucus. Measured biochemically, nodules contained more pepsinogen than adjacent more normal mucosa (p < 0.05), and this effect was largely attributable to the greater mass of nodules. Infection of sheep with H. contortus was associated with generalised hyperplasia, characterised by increased numbers of mucopeptic cells and in at least one animal with reductions in parietal cell numbers. At the same time, the zymogen granule content of chief cells was reduced. Similar changes were occasionally seen in sheep infected predominantly with O. circumcincta. Generalised hyperplasia is likely to be indicative of the presence of ambulatory parasitic stages as opposed to those confined to nodules. The potential for the enhanced production of pepsinogen by increased numbers of cells with a joint mucous cell and zymogenic cell phenotype may offset decreases in the numbers of chief cells or reductions in chief cell activity.     

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.     

Serum pepsinogen concentrations in strongyle-free French dairy goats

Serum samples from 533 strongyle-free goats were analysed to assess the normal values of pepsinogen concentration. Results obtained from adult goats ( > 12 months) indicated higher values of pepsinogen compared with sheep and cattle, with more than 25% of the animals exceeding 1000 milliunits of released tyrosine (mU TYR). Weaned goats less than 6 months old had lower pepsinogen concentrations than the adult goats: 490 ± 175 mU TYR vs. 825 ± 414 mU TYR for the French Alpine breed and 397 ± 135 mU TYR vs. 709 ± 274 mU TYR for the Saanen breed. Saanen goats showed lower pepsinogen values than French Alpine goats. Additional sources of variation included farm and duration of lactation. Pepsinogen determinations were highly repeatable for 4.5 months, suggesting a pronounced stability of pepsinogen levels for the same non-infected animals.     

Abomasal secretion in sheep receiving adult Ostertagia circumcincta that are prevented from contact with the mucosa

AIMS: Both adult and larval Ostertagia circumcincta infections raise abomasal pH and serum gastrin and pepsinogen concentrations, either because of physical effects of the worms or from their chemical secretions. The study was designed to examine whether adult worms require contact with the gastric mucosa to effect changes in gastric secretion. METHODS: Abomasal pH and serum gastrin and pepsinogen concentrations were measured in four groups of sheep: Group A (n = 4): abomasal contents containing about 18,000 adult O. circumcincta were obtained from donor sheep, concentrated and infused into 5 microm mesh porous bags attached to surgically implanted abomasal cannulae. A second worm transplantation was carried out 1 week later to assess worm survival after 16 hours. Group B (n = 4): about 9000 adult worms, recovered after migration out of abomasal contents set in agar, were placed in small 5 microm mesh bags which were inserted through indwelling abomasal cannulae and left for 3 days. Group C (n = 2): about 3000 adult worms from the population recovered from agar were infused through abomasal cannulae which allowed. free movement in the abomasum. Group D (n = 3) was left uninfected. RESULTS: Worms transplanted directly into the abomasum (Group C) caused rapid and marked effects on abomasal secretion. Adult O. circumcincta died within 16 hours of transfer into the abomasum when they were restrained within porous bags. Nevertheless, in sheep receiving 18,000 worms, abomasal pH increased soon after new feed was presented on Days 1, 2 and 4 after worm transfer; serum gastrin was elevated in three sheep from 113 hours and serum pepsinogen increased in one animal. Sheep receiving 9000 worms showed similar trends but the results were equivocal. CONCLUSIONS: Adult O. circumcincta prevented from physical contact with the gastric mucosa by restraint in porous bags are able to raise abomasal pH. This study implicates parasite excretory-secretory products in mediating changes in gastric secretion caused by adult abomasal worms.     

The relationship between the number and size of nematodes in the abomasum and the concentration of pepsinogen in ovine plasma.

Six-month-old lambs that had been naturally infected with predominantly Teladorsagia (Ostertagia) circumcincta were tested for plasma pepsinogen concentrations because pepsinogen concentrations may reflect the extent of damage to the abomasum. The distribution of pepsinogen concentrations among these lambs was positively skewed with most individuals having relatively low concentrations. Pepsinogen concentrations were more strongly associated with variation in the mean length of the adult female worms than with variation in the number of nematodes present. Previous trials have suggested that genetic variation in the growth of lambs is strongly influenced by genetic variation in worm length. Together these results imply that variation among lambs in the pathogenic effects of T. circumcincta depends upon the mean size of the worms as well as the number of worms present.     

Effect of an antimuscarinic drug on the plasma pepsinogen activity of sheep infected with Ostertagia circumcincta

The antimuscarinic drug atropine caused a marked fall in plasma pepsinogen values of sheep with burdens of Ostertagia circumcincta and this response was greater in animals which had higher plasma pepsinogen values before administration of the drug. The response was shown to occur whether the elevated plasma pepsinogen values were a consequence of a larval infection in previously naive or exposed animals or of adult parasites directly transplanted into the abomasum of naive lambs.     

Blood gastrin and pepsinogen responses to subclinical infection with Ostertagia ostertagi in adult dairy cattle

Blood gastrin and pepsinogen responses to a single infection with 100,000 Ostertagia ostertagi infective larvae in lactating dairy cows were investigated. None of the infected cows showed signs of clinical ostertagiasis, nor was there any difference in live weight gain, milk yield or faecal egg count between groups. Pepsinogen levels of the infected group were significantly elevated between days 3 and 24 after infection (peak 1041 mU tyrosine; day 14). In contrast, there was no significant difference in blood gastrin levels between infected and control animals suggesting that few adult worms had become established in the former group. These data are compared with the increases in both gastrin and pepsinogen levels recorded in susceptible calves exposed to the same level, pattern and strain of ostertagia infection in a previous experiment. It is suggested that gastrin assay may be of value in adult cattle for indicating when elevated pepsinogen levels are merely associated with a rise in larval intake and not with the establishment of large adult worm burdens.     

Experiments on transmission of an unidentified Theileria sp. to small ruminants with Haemaphysalis qinghaiensis and Hyalomma anatolicum anatolicum

Experiments on the transmission of an unidentified Theileria sp. infective for small ruminants by Haemaphysalis qinghaiensis and Hyalomma anatolicum anatolicum were carried out. Three Theileria-free batches of adult, larvae, and nymphs of laboratory reared H. qinghaiensis and Hy. a. anatolicum ticks were infected by feeding them on sheep infected with Theileria sp. The Theileria sp. was originally isolated from adult ticks of H. qinghaiensis, by inoculation of blood stabilates or tick transmission. H. qinghaiensis has been shown to be capable of transmitting the Theileria sp. infective for small ruminants transstadially to sheep and goats. The nymphs developed from the larvae engorged on the sheep infected with the parasite transmitted the pathogen to splenectomized sheep with prepatent periods of 30, 31 days, respectively; but the subsequent adult ticks of H. qinghaiensis derived from the nymphs did not transmit the pathogen to sheep. However, adults developed from the nymphs engorged on the sheep infected with the parasite transmitted the pathogen to sheep with prepatent periods of 24-27 days. The larvae, nymphs and adult ticks derived from female H. qinghaiensis ticks engorged on infected sheep were not able to transmit the parasite transovarially. The same experiments were done with Hy. a. anatolicum, but examination for presence of piroplasma of Theileria sp. from all animals were negative, demonstrating that Hy. a. anatolicum could not transmit the organism to sheep or goats.     

Leucopenia in Trypanosoma vivax infection of sheep

Experimental Trypanosoma vivax infection of sheep produced a moderate leucopenia associated with a lymphopenia and eosinopenia. The total white blood cell counts of adult mice were not significantly depressed when inoculated with plasma from T. vivax-infected sheep. These observations suggested that the plasma of the infected sheep did not have a factor which could depress leucopoiesis in vivo.     

Gastrin and pepsinogen changes during an Ostertagia ostertagi challenge infection in calves

Daily changes in serum gastrin and pepsinogen concentration have been studied during two types of infection with Ostertagia ostertagi in calves. In a first experiment two calves were trickle infected (10 times 10,000 L3 Ostertagia) and two animals received a single infection of 100,000 L3 Ostertagia. Gastrin and pepsinogen changes are discussed in relation to adult wormburdens. The second experiment involved 8 calves and was designed to investigate pepsinogen and gastrin changes following a challenge infection in previously sensitized calves. The high dosed group was infected with 5,000 L3 O. ostertagi during 30 days, the low dosed group received 500 L3 O. ostertagi and group 3 served as uninfected control. At day 41 post infection all animals were treated with oxfendazole and on day 61 challenged with 100,000 L3 O. ostertagi. Only in the high dosed group a distinct pepsinogen and gastrin reaction was noticed. Both parameters dropped to almost preinfection levels after treatment. Two days post challenge a moderate rise (+/- 1,000 mU tyr) of the pepsinogen concentration was observed in the previously infected animals and gastrin showed a temporary slight increase in several animals 8 to 10 days post challenge. The effect of treatment and challenge infection is discussed in relation to gastrin and pepsinogen changes and immunity.     

A sequential study of the pathology associated with the infection of sheep with adult and larval Ostertagia circumcincta

Disturbances in the physiology of the abomasa of sheep infected with either adult Ostertagia circumcincta given via abomasal cannulae, or larvae (L3) given intraruminally were matched by pathological changes in tissues collected by repeated mucosal biopsy. Within 2-3 days of the transplant of adult worms, abomasal pH had increased markedly in five out of six animals, and there also had been rapid increases in serum gastrin and pepsinogen concentrations in all animals. Reductions in parietal cell number were recorded as early as 1 day after the transplant of adults and were associated with the rapid accumulation of many neutrophils and eosinophils. Mucosal hyperplasia, with increased numbers of cells closer in appearance to mucous/mucous neck cells, was a relatively late development, being most pronounced in the latter part of the infection. In sheep given larvae, changes in secretory physiology were again matched by a concurrent fall in parietal cell number and by the accumulation of inflammatory cells. Changes became maximal when most worms could be expected to be present as adults, confirming the role of adults in the natural disease. Some abnormalities were detected in biopsies collected from animals maintained free of parasites and, although milder in degree, there were similarities to those observed in parasitised tissues, there being fewer parietal cells, a modest degree of mucous cell hyperplasia and inflammatory infiltrates of predominantly neutrophils. These changes were the likely result of trauma to the tissues in the immediate vicinity of the cannula, due either to the presence of the cannula itself or to the frequent collection of biopsy material from areas close to it.     

The effects on merino lambs of chronic infection with Trichostrongylus rugatus

Four groups of six 5-month-old merino lambs were exposed to infection with 12,000 larvae of Trichostrongylus rugatus per week and one group was killed at each of 3, 6, 9 and 12 weeks. Numbers of adult worms increased in an approximately linear manner throughout the experiment; the percentage of larvae developing to adults remained between 35 and 25% throughout the course of the experiment. Sub-total villus atrophy was evident in the anterior small intestine of each group of infected sheep and significant reductions occurred in the plasma concentrations of albumin and phosphate. Serum globulin and calcium concentrations rose in infected animals. No clinical signs were observed in infected sheep, no alteration in bone histology was detected and no decrease in growth rate occurred.     

Preparation of suspensions of Hyalomma excavatum ticks infected with Theileria annulata

Partially engorged adult Hyalomma excavatum ticks infected with Theileria annulata were reared for the preparation of an infective suspension. About 6000 partially engorged infected adults were obtained from 420 non-infective adult ticks. The entire cycle required about 4 months. Six rabbits were used for the production of the fully engorged females. The larvae were fed on 180 gerbils, the nymphs on 17 infected calves and the partially fed adults on 22 goats, 7 sheep and 7 rabbits The adult ticks did not show any host preference.     

Diagnostic value of gastrin for clinical bovine ostertagiosis.

Gastrin values were evaluated in 130 parasite naive calves, in 61 first season grazing calves during six field trials and in 8 experimentally infected adult immune cows. The gastrin values were linked to pepsinogen levels and daily weight gain. Also the influence of an anthelmintic treatment on pepsinogen and gastrin values was assessed during a clinical outbreak of ostertagiosis in a group of first season grazing calves. Mean gastrin levels in parasite naive calves were 106 pg/ml. Results show that a group mean of 400 pg/ml gastrin in first season grazing calves indicates a reduced daily weight gain but with no obvious clinical signs. During clinical outbreaks mean gastrin levels frequently reached 1,000 pg/ml with a severe weight loss and a mean pepsinogen level of 5,000 mU tyr. The serum gastrin concentration was strongly reduced 4 days post treatment. No gastrin response was noted following an Ostertagia challenge in adult immune cows. The value of gastrin as a diagnostic aid for ostertagiosis is discussed in relation to pepsinogen, the adult worm burden, larval inhibition and the technique involved in assessing gastrin.     

Copper supplementation of sheep

The effect of 6 methods of copper supplementation on copper status was examined in Merino sheep at pasture. Plasma copper concentrations were not affected by any of the treatments. Liver copper concentrations in sheep given an oral dose of 3 g of oxidised copper wire particles were significantly greater than those of untreated sheep for the duration of the experiment of 80 weeks. Subcutaneous injections of 18 mg of copper as diethylamino cupro -oxyquinoline sulphonate produced small, transient increases in liver copper. Single oral doses of 150 mg of copper as copper sulphate or 30 mg of copper as copper oxychloride produced little or no detectable increase in liver copper. Liver copper concentrations of untreated sheep were lowest in winter, apparently associated with increased damage to the abomasum, as indicated by raised plasma pepsinogen activities.     

Survey of Gastric Lesions and Blood Pepsinogen Levels in Pigs in Burkina Faso

The purpose of the study was to investigate the prevalence of gastric lesions and to provide diagnostic values for serum pepsinogen in non-infected pigs and in pigs with gastric disease. In an abattoir survey, the pepsinogen concentrations were measured in the serum from 62 non-infected pigs, 33 pigs with gastric lesions and 17 pigs infected with Hyostrongylus rubidus, using a specific radioimmunoassay (RIA). The mean (±SE) pepsinogen concentrations in the serum of non-infected pigs, in pigs with gastric ulcers, and in pigs with a heavy H. rubidus infection were 630.8±39.2 ng/ml, 1084.5±166.2 ng/ml and 1095.2±102.3 ng/ml, respectively (p<0.05). Because of the higher concentrations of pepsinogen in the blood of pigs with gastric ulcers or parasitic infections, it is suggested that the measurement of serum pepsinogen by RIA may be an effective biochemical approach to the diagnosis of chronic gastric disorders in pigs.     

Uptake of albendazole and albendazole sulphoxide by Haemonchus contortus and Fasciola hepatica in sheep

The pattern of in vivo uptake of albendazole (ABZ) and its major metabolite, ABZ-sulphoxide (ABZSO), by Haemonchus contortus and Fasciola hepatica recovered from ABZ-treated sheep, was investigated. Concentration profiles of both compounds were simultaneously measured in target tissues/fluids from the same infected sheep. In addition, the proportion of the (+) and (-) ABZSO enantiomers was determined in plasma, bile and F. hepatica recovered from treated sheep. Sheep naturally infected with H. contortus were intraruminally (i.r.) treated with ABZ (micronized suspension, 7. 5mg/kg) and the plasma concentrations of ABZSO and ABZ-sulphone (ABZSO(2)) determined in addition to the concentration of ABZ and ABZSO in H. contortus, abomasal mucosa and fluid content samples. In addition, F. hepatica artificially infected sheep were treated i.r. with the same ABZ suspension (7.5mg/kg), and samples of blood, bile, liver tissue and adult flukes were collected and analysed by HPLC to determine the concentrations of ABZ and both enantiomers of ABZSO. ABZSO and ABZSO(2) were the analytes recovered in plasma with ABZ and ABZSO present in H. contortus. ABZ was the analyte recovered at the highest concentration in H. contortus and abomasal mucosa, whereas higher concentrations of ABZSO were measured in abomasal fluid content. Only low concentrations of ABZ were detected in F. hepatica and bile, but markedly higher concentrations of ABZ were measured in liver tissue. ABZSO was the main molecule recovered in F. hepatica, plasma and bile samples collected from ABZ-treated sheep. The (+) enantiomer of ABZSO was recovered at a higher proportion in plasma (75%), bile (78%) and F. hepatica (74%) after ABZ administration to infected sheep.