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PubMed1988

Evaluation of abomasal enzyme and hormone levels in the diagnosis of ostertagiasis.

Pathophysiological changes in the ruminant abomasum caused by Ostertagia infections include changes in the activity and concentration of gastrointestinal enzymes and hormones. Under certain circumstances, increases in concentration also occur in the bloodstream and, as such, are detectable. Determination of serum pepsinogen levels is useful in evaluating the risk or presence of ostertagiasis Type I in a herd. It seems less reliable when used to diagnose (pre) ostertagiasis in individual animals. Measurement of the concentration of other zymogens is not useful. The variations in methodology to determine pepsinogen levels (e.g. biochemical and immunological measurements) are discussed. Serum gastrin levels are, generally, increased in animals with ostertagiasis. At present, gastrin is mainly determined by RIA assays using human gastrin antibodies, but few baseline data are available on normal levels in ruminants. The use of gastrin determination as a diagnostic tool in Ostertagia-infected ruminants is limited.

Abomasum↗
PubMed1988

Epidemiology and control of bovine ostertagiasis in South America.

Gastrointestinal parasitism has been recognized by practitioners as the most common disease in beef cattle, mainly in weaning calves and fattening steers. Among the different genera, Ostertagia ostertagi is the predominant parasite in the temperate climate, in which the major beef and dairy cattle area of South America is situated. Outbreaks of Type I ostertagiasis are usually seen after weaning time (autumn-winter) when larvae counts are high and food availability is low. The development of the disease is rapidly established and 15-30 kg are lost in 30-50 days. Epidemiological studies have demonstrated a fast evolution of parasite eggs to larvae (L3) in summer (1 week or less), evolution being 30-45 days during winter. Inhibition O. ostertagi occurs during spring (September-December) and development resumes in late summer and early autumn. The production effect is seen as a significant reduction in body weight gain and occasionally clinical Type II ostertagiasis appears. A similar epidemiological pattern of inhibition of Ostertagia sp. has been recorded in Uruguay and temperate areas in southern Brazil.

Animals↗
PubMed1988

Sequential histopathologic changes of type I, pre-type II and type II ostertagiasis in cattle.

Yearling cattle in Louisiana were examined at monthly intervals for abomasal nematode burdens and histological lesions over a year. Tracer calves were grazed for 3 to 4 weeks and removed from pasture for 2 to 3 weeks, then slaughtered; a few animals were killed in extremis shortly after removal from pasture. Histological changes were correlated with worm burdens and characterized according to the type of Ostertagia ostertagi infection present. In cattle with acute Type I ostertagiasis, changes varied from eosinophil infiltration to glandular dilation and slight mucous cell hyperplasia with submucosal edema. During the summer months the cattle had worm burdens that were primarily early 4th stage larvae (EL4), with changes characterized by minimal glandular dilation and mucous cell metaplasia and moderate lymphoid cell proliferation and with intramucosal migration of EL4. In the autumn, the maturation of EL4 produced the Type II syndrome with severe glandular changes, prominent mucosal hyperplasia and marked lymphoid cell accumulation. With increased duration of the pre-Type II interval, there was greater development of the subepithelial lymphoid tissue and increased frequency of epithelial globule leukocytes. The lymphoproliferation which occurred during the prolonged pre-Type II interval appeared to be related to the increased severity and mortality seen with the Type II ostertagiasis syndrome.

Abomasum↗
PubMed1993

Evaluation of pepsinogen, gastrin and antibody response in diagnosing ostertagiasis.

Ostertagia ostertagi is widely distributed and is one of the most important parasites affecting young bovine livestock. There is, therefore, a substantial need for sensitive and specific parameters in support of diagnosis of ostertagiasis, especially for subclinical disease related to production losses. In this review, the value and application of pepsinogen, gastrin and antibody response as diagnostic tools are discussed. These three parameters are useful and comparable for confirming clinical disease in calves during their first grazing season. However, their value for detecting subclinical parasitism is questionable. Differences in the course of gastrin and pepsinogen late in the grazing season can be correlated with larval inhibition and the possibility of ostertagiasis Type II. Relatively few serological methods have been developed for the immunodiagnosis of Ostertagia and until now the indirect antibody-detecting enzyme-linked immunosorbent assay (ELISA) has been the method of choice. Antibody measuring methods have several disadvantages, most notably a lack of sensitivity and specificity, which limits their use in longitudinal epidemiological studies. Considering the necessity of cost effectiveness and ease of use, it is anticipated that additional work will result in the enhancement and quality of current immunodiagnostic methods.

Animals↗
PubMed1993

Ostertagiasis in the cow and weaned calf in the northeastern USA.

Most gastrointestinal nematode infections of cattle in the northeast USA are combinations of Ostertagia ostertagi and Cooperia oncophora. These infections are usually of little consequence in adult cattle because of immunity and consequent low levels of infection. Some work has been done on the effects of infection on milk production but the results are equivocal. Clinical ostertagiasis in calves can lead to mortality. Such outbreaks are often associated with situations where calves are pastured at an early age onto special calf pastures that are used consistently for this purpose. Subclinical ostertagiasis is more usual in this region where light infections become established in calves with no obvious clinical signs. Such infections exact a toll on productivity in the form of decreased weight gains, decreased carcass quality, reduced nitrogen balance and negative effects on post-absorptive protein metabolism. Subclinical infections can also cause transient suppression of cell-mediated immune responses in calves. Increases in fecal worm egg counts of cows have been shown to occur during the spring months and these may contribute to increased contamination of pastures. Ostertagia infective larvae overwinter successfully on pasture and can persist until midsummer. Typical egg production patterns in calves involve a prepatent period, after introduction to pasture in mid to late May, of approximately 3 weeks. Peak egg production occurs at about 6-8 weeks and is followed by a gradual decline in egg counts into the fall. Hypobiosis is very apparent in this region and is most pronounced in late fall (October-November).(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1979

Bovine ostertagiasis: a changing epidemiological pattern?

An unusual epidemiological pattern in bovine ostertagiasis is described in which clinical ostertagiasis occurred in calves grazed on a silage aftermath from late July. The calves were treated with the anthelmintic levamisole prior to grazing the aftermath and the latter had not been grazed since the previous autumn. Analysis of the herbage larval counts suggests that delayed emergence of overwintered Ostertagia ostertagi L3 from the soil was the most likely source of the infection.

Animals↗
PubMed1979

Observations on ostertagiasis in young cattle over two grazing seasons with special reference to plasma pepsinogen levels.

The epidemiology of ostertagiasis in south west Scotland was studied in groups of cattle grazed through two successive grazing seasons separated by a period of winter housing. Towards the end of the first grazing season (September) the numbers of infective larvae (L3) on the pasture had increased to high levels (up to 24,000 L3 per kg) which resulted in high faecal egg counts, worm burdens, plasma pepsinogen levels and the occurrence of clinical ostertagiasis in the calves. By late spring (May) at the onset of the second grazing season, there was an almost complete mortality of the overwintered L3 on the pasture followed by the appearance of moderately high numbers of a new population of L3 in September (up to 9000 L3 per kg). The latter increase in the numbers of L3 was reflected by negligible faecal egg counts, low worm burdens and a moderate elevation of plasma pepsinogens in the second year animals. It therefore seems that although young cattle acquire a good immunity to Ostertagia ostertagi after one season at grass the small infections established in the early part of the second season are capable of contaminating the pasture to levels which could be dangerous for susceptible stock. An allergic reaction in the abomasal mucosa could be the basis of the elevated pepsinogens present in the second year animals.

Animals↗
PubMed1976

Type II ostertagiasis in adult cattle.

During the spring of 1975 outbreaks of ostertagiasis affecting adult cattle were recorded from several beef herds. Two of these outbreaks, one involving an autumn calving herd and the other spring calving, were investigated in detail. The clinical, biochemical, haematological, parasitological and pathological findings are described and were similar to those characteristic of type II ostertagiasis in immature cattle.

Animals↗
PubMed1984

Leukokinesis in bovine ostertagiasis: stimulation of leukocyte migration by Ostertagia.

A blind-well chemotaxis chamber method was used to indicate migration stimulation of bovine neutrophil and eosinophil polymorphonuclear leukocytes and macrophages as related to ostertagiasis. Live exsheathed Ostertagia ostertagi 3rd-stage larvae (L3) and soluble L3 antigen (SLA), prepared by freeze thawing and sonic disruption of L3, enhanced cellular migration for eosinophils, but not for neutrophils and macrophages. Products of lymphocytes cultured with SLA for 3 to 6 hours were also examined, using lymphocytes from peripheral blood of helminth-free cattle and cattle infected with O ostertagi or Trichostrongylus axei. Lymphokines that enhanced cellular migration of neutrophils, eosinophils, and macrophages were present in culture supernatants of SLA-stimulated lymphocytes from O ostertagi-infected cattle, but not from cattle infected with T axei or helminth-free cattle. Seemingly, L3 and SLA were stimulants of eosinophil migration. Further, neutrophil, eosinophil, and macrophage migration was modulated by lymphokines produced by SLA-stimulated lymphocytes from cattle with ostertagiasis.

Animals↗
PubMed1986

The sequential development of type I and type II ostertagiasis in young cattle with special reference to biochemical and serological changes.

The sequential development of Type I and Type II ostertagiasis over a 2-year period in the same naturally infected cattle is described for the first time. Particular reference is made to biochemical and serological changes. Positive relationships were demonstrated between the clinical signs of both Type I and Type II disease, and marked increases in the levels of plasma pepsinogen, plasma gastrin and antibody titres to adult Ostertagia antigen. At necropsy, there were significant relationships between the combined total of adult and developing 5th stage larvae of Ostertagia spp. and the levels of both plasma pepsinogen and gastrin. By the end of the second grazing season the cattle had acquired an immunity to infection with Ostertagia spp. and had very low burdens of this parasite at necropsy. However some of these cattle maintained elevated plasma pepsinogen levels when under natural challenge by Ostertagia spp. larvae and the aetiology of these changes and the problems of diagnosis using this parameter are discussed. Similar trends of infection were observed for Cooperia oncophora, although resistance to the parasite developed more rapidly.

Abomasum↗
PubMed1987

The effects of late turnout on the epidemiology and control of ostertagiasis in calves.

The main purpose of this experiment was to study the importance of time of turnout on the epidemiology and impact of ostertagiasis in calves pastured for the first time. When time of turnout onto permanent pasture was postponed from mid-May to mid-June, fewer overwintered larvae were picked up and re-contamination of pastures was markedly diminished. Consequently, the acquisition of loss-producing parasite burdens in the late part of the season was significantly reduced. Late turnout as a control strategy is discussed in relation to other preventive measures.

Animals↗
PubMed1988

The epidemiology of bovine ostertagiasis in the north temperate regions of North America.

Ostertagia ostertagi is widely distributed and is the most pathogenic of the parasitic nematodes affecting cattle in this region. Clinical ostertagiasis is seen mainly in calves and yearlings but outbreaks tend to be sporadic; the subclinical disease is of greater importance. Studies on the population dynamics of the free-living stages have shown that infective larvae can survive on pasture over the relatively severe winter conditions encountered in this region but that such pasture contamination declines during the succeeding grazing season and is lost by midsummer. In the host there is gradual acquisition of worms from pasture over the summer period, with relatively high burdens accumulating in the autumn. A dramatic shift in the proportion of adult to immature worms occurs during the autumn (October). By the time calves are housed, the proportion of larvae (mainly L4) is greater than 80%. This relative distribution of adults to larvae continues through the winter months until early spring when there appears to be a shift to a higher proportion of adults, presumably due to resumption of development of the L4. These persistent L4 stages are considered to be undergoing hypobiosis. Spring infections of calves appear to be mainly acquired from larvae that have successfully overwintered on pasture, and availability of these larvae is drastically reduced by midsummer. There appears to be negligible development of the eggs that result from the spring infections until late summer and early autumn. At this time because of favorable climatic conditions there is rapid larval development which can result in heavy infections in susceptible calves in the autumn.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Control strategies for ostertagiasis.

There are currently four major options for control of ostertagiasis and other ruminant gastrointestinal parasites. These are the traditional, suppressive, integrated and strategic approaches. Strategic dosing is the most realistic and beneficial approach for most regions of the world, including the U.S.A. It is effective, practical, labor-saving and can yield big economic returns. Today this approach is even more appropriate because of important advances in the technology of controlled release and pulse-release devices. Top priority in worm control programs should be given to dairy replacement heifers in their first year at pasture and to beef calves in the immediate post-weaning period. This is preferable to recommendations for blanket treatment of all beef and dairy cattle, regardless of age, immune status or pasture infectivity. An anthelmintic overkill is both wasteful and potentially harmful in that it increases the selection pressure for drug resistance. It is suggested that better dissemination of information is needed to make producers aware of the benefits of strategic dosing programs. This would eliminate much of the confusion about parasite control and focus attention on simple and effective programs that could significantly reduce current losses to the livestock industries.

Animals↗
PubMed1988

Preliminary report: immunodiagnosis of pre-type II ostertagiasis.

Ostertagia ostertagi soluble antigens were prepared by gel electrophoresis and electrophoretic transfer onto nitrocellulose for enzyme-linked immunosorbent assays with serum probes. Serologic responses to L3-derived antigen of approximately 32 kDa may be unique and diagnostic for cattle harboring inhibited larvae, or pre-Type II ostertagiasis. Specificity was evaluated by comparing sera from pre-Type II cattle to sera from Type I, uninfected, Fascioloides magna infected, Fasciola hepatica infected or Cooperia oncophora infected cattle.

Animals↗
PubMed1993

Current and future prospects for control of ostertagiasis in northern Europe--examples from Denmark.

This review primarily discusses the status and prospects for control of bovine ostertagiasis in northern Europe, with examples from Denmark. There are different ongoing developments in agricultural systems and practices, and methods and possibilities for practical control depend on the intensity and specialisation of these; the modern dairy farm remains at highest risk of parasitism, owing to increasing stocking densities and limited natural control elements at hand. Epidemiology and course of infections are significantly influenced by the gradual build-up of acquired immunity, which usually contributes to prevent loss-producing effects in second season and older animals. It may be of doubtful value to exaggerate worm control in first season animals, because this may reduce development of immunity with the risk of translocating parasite problems from the young to the older, economically more important age categories of animals. A number of reasons for adopting an overall consideration on worm control and performance throughout adolescence is emphasised. Control by management relies on a fairly detailed insight into local transmission factors of Ostertagia ostertagi and related trichostrongyles. No doubt future investigations will provide important additional knowledge in this area. Anthelmintics will continue to constitute a major control measure, but it is unlikely that there will be any acceleration in the rate of commercial release of new compounds. However, ongoing modifications and new formulations of existing anthelmintics will continue to be produced, and implementation at the farm level of the proper use of anthelmintics and other control measures will be one of the important tasks of the coming century. Until now, the development of anthelmintic resistance in cattle has been negligible, but it may possibly pose a potential risk over the coming decades. With regard to some new anthelmintics that have environmental concerns related to their faecal excretion, this should be carefully examined in the future. Control in the form of vaccination or biological control by microfungi or others would be attractive alternatives that should be given a high research priority. Yet, at present it is not easy to predict which of these may lead to feasible, practical control.

Agriculture↗
PubMed1987

Population biology of Ostertagia ostertagi and anthelmintic strategies against ostertagiasis in calves.

Five chemoprophylactic or chemotherapeutic strategies against bovine ostertagiasis are compared using a mathematical model of the population biology of Ostertagia ostertagi. The model offers a means of screening novel strategies prior to their further investigation in the field. Under conditions of climate and management typical of many regions in Northern temperate Europe, the model indicates that all of the tested prophylactic strategies will result in a profound reduction in the intensity of infection in grazing beef calves when compared with an untreated control group or the simple therapeutic protocol. Not all of those strategies which caused diminution in the scale of the midsummer rise in pasture larval contamination resulted in progressively less contaminated pastures in subsequent years. Moreover, the reproductive potential of the parasite is so great that the principal advantage of the 'pasture cleaning' effect that is the consequence of some protocols is not that the pasture may eventually be used to graze untreated calves but that the treated animals are subjected to a progressively smaller parasitic challenge with the concomitant pay-off in production gains.

Animals↗
PubMed1979

A prediction model for bovine ostertagiasis.

A mathematical model based on development and mortality rates, and incorporating data on the infectivity, fecundity and migratory behaviour of Ostertagia ostertagi, was used to predict the level of pasture contamination and the occurrence of clinical ostertagiasis in grazing calves during 1975 and 1976. A comparison of the predicted and observed events showed a good correlation.

Animals↗
PubMed1981

Studies on the control of bovine ostertagiasis using a morantel sustained release bolus.

The efficacy of a morantel sustained release bolus to control ostertagiasis in grazing calves was assessed. Administration of the bolus into the rumen of calves immediately before turnout on to spring pasture in May substantially reduced the level of pasture contamination with infective larvae later in the season. Compared with controls there was a 71 per cent reduction in worm burdens acquired over the entire grazing season with a mean improvement in weight gain of 24 kg. When administration was delayed until midsummer (July) a good anthelmintic effect was obtained but there was little reduction in pasture contamination levels. Worm burdens acquired over the grazing season were reduced by only 48 per cent with a mean weight gain advantage of only 9 kg compared with controls. The control obtained against Dictyocaulus viviparus by both treatments was not absolute, failing to prevent the development of mild parasitic bronchitis.

Animals↗