The presence of an early L4 larvae population in relation to the immune response of calves against Ostertagia ostertagi

Hilderson, Hans; Vercruysse, Jozef; Graaf, Dirk C. de; Bastiaensen, P.; Fransen, J.; Berghen, P.

doi:10.1016/0304-4017(93)90027-k

Cited by 22 publications

(16 citation statements)

References 22 publications

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“…The infection dynamics shown in Figure 1 match the findings of Roberts and Grenfell [7], and the trends echo empirical data [47]–[50], with peak parasite burdens within realistic bounds [30], [47], [53]. The model also reproduces the grazing behaviours empirically observed at multiple scales in livestock grazing systems [40], [17], [54], [23] At the start of the grazing season, infection is initiated through ingestion of infective larvae that have over-wintered on pasture.…”

Section: Discussionsupporting

confidence: 74%

“…Using values outlined in the main parameterisation section, the model successfully reproduces the parasite dynamics empirically observed in livestock grazing systems [7], [47]–[50]. The introduction of susceptible hosts onto contaminated pasture accounts for the rapid increase in ingested larvae and adult parasites in the host, and the subsequent acquisition of immunity accounts for the consequent decline in parasite burden (Figure 1).…”

Section: Resultsmentioning

confidence: 83%

“…The life expectancy of the adult parasites in the host is approximately 5 weeks [35] ( τ = 0.00002). With these parameter values, the model successfully reproduces the parasite dynamics empirically observed in livestock grazing systems [7], [47]–[50].…”

Section: Methodsmentioning

confidence: 76%

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Modelling Parasite Transmission in a Grazing System: The Importance of Host Behaviour and Immunity

et al. 2013

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Parasitic helminths present one of the most pervasive challenges to grazing herbivores. Many macro-parasite transmission models focus on host physiological defence strategies, omitting more complex interactions between hosts and their environments. This work represents the first model that integrates both the behavioural and physiological elements of gastro-intestinal nematode transmission dynamics in a managed grazing system. A spatially explicit, individual-based, stochastic model is developed, that incorporates both the hosts’ immunological responses to parasitism, and key grazing behaviours including faecal avoidance. The results demonstrate that grazing behaviour affects both the timing and intensity of parasite outbreaks, through generating spatial heterogeneity in parasite risk and nutritional resources, and changing the timing of exposure to the parasites’ free-living stages. The influence of grazing behaviour varies with the host-parasite combination, dependent on the development times of different parasite species and variations in host immune response. Our outputs include the counterintuitive finding that under certain conditions perceived parasite avoidance behaviours (faecal avoidance) can increase parasite risk, for certain host-parasite combinations. Through incorporating the two-way interaction between infection dynamics and grazing behaviour, the potential benefits of parasite-induced anorexia are also demonstrated. Hosts with phenotypic plasticity in grazing behaviour, that make grazing decisions dependent on current parasite burden, can reduce infection with minimal loss of intake over the grazing season. This paper explores how both host behaviours and immunity influence macro-parasite transmission in a spatially and temporally heterogeneous environment. The magnitude and timing of parasite outbreaks is influenced by host immunity and behaviour, and the interactions between them; the incorporation of both regulatory processes is required to fully understand transmission dynamics. Understanding of both physiological and behavioural defence strategies will aid the development of novel approaches for control.

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Section: Discussionsupporting

confidence: 74%

Section: Resultsmentioning

confidence: 83%

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Modelling Parasite Transmission in a Grazing System: The Importance of Host Behaviour and Immunity

et al. 2013

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“…Another possibility is that the young adults emerging from the abomasai glands (causing epithelial disruption and inflammation) provide the continuous antigenic stimulus necessary for development of immunity, rather than the arrested larvae per se. This could explain why in the present experiment a reduction in Ostertagia worm burden (although not significant) was only observed in calves which maintained elevated pepsinogen levels until the end of the primary infection period, while in the study of Hilderson et al (1993) worm burdens were not reduced after a decrease of pepsinogen levels from day 67 onwards.…”

Section: Discussioncontrasting

confidence: 70%

“…Therefore, the levels of antibodies and pepsinogen after the primary infection period could be used indirectly to predict whether or not animals had acquired immunity. In contrast, in an experiment with an identical infection schedule for 18 weeks (Hilderson et al, 1993), a decrease of pepsinogen levels from day 67 onwards, indicating that fewer worms reached the adult stage, was interpreted as a sign of developing immunity. This was not confirmed by a reduction in worm burdens after challenge, although a higher percentage of worms were inhibited L 4 larvae.…”

Section: Discussionmentioning

confidence: 88%

The effect of truncated infections with Ostertagia ostertagi on the development of acquired resistance in calves

Claerebout

Hilderson

Meeus

et al. 1996

Veterinary Parasitology

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The relative contribution of the third (L3), fourth (L4) and adult stages of Ostertagia ostertagi to the development of immunity was assessed in calves which were either continuously infected during 21 weeks or subjected to infections truncated by anthelmintic treatment at the L 3 or L 4 stage. A fourth group remained uninfected (control group). Faecal samples and blood samples were collected weekly for faecal egg counts and determination of pepsinogen and antibody levels. Only the continuously infected animals showed positive egg counts, which fell towards the end of the primary infection period. Pepsinogen and antibody levels remained high in the continuously infected group until the end of the primary infection period. At that time, they were significantly higher compared to the control calves, with intermediate values in the truncated infection groups. After the 21 weeks primary infection period all animals were dewormed. To evaluate the protection provided by the different immunisation protocols, all animals were challenged l week later with 156000 Ostertagia L 3, spread over 12 consecutive days. The marked reduction in egg counts following challenge infection indicated a certain degree of immunity in the continuously infected calves, which was confirmed at necropsy by the reduced worm burdens, the high percentage of inhibited early L 4 larvae, the reduced size of the adult worms and the higher numbers of mucosal mast cells in this group. Numbers of globule leucocytes and eosinophils were not significantly different from the control group. Infections truncated by anthelmintic treatment elicited poor development of immunity as shown by the egg output after the challenge infection Claerebout et al./ Veterinary Parasitology 66 (1996) 225-239 and the percentages of arrested larvae and the lengths of adult worms which were intermediate to those of the continuously infected calves and control animals.

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Antler asymmetry and immunity in reindeer

Lagesen¹,

Folstad²

1998

Behavioral Ecology and Sociobiology

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The presence of an early L4 larvae population in relation to the immune response of calves against Ostertagia ostertagi

Cited by 22 publications

References 22 publications

Modelling Parasite Transmission in a Grazing System: The Importance of Host Behaviour and Immunity

Modelling Parasite Transmission in a Grazing System: The Importance of Host Behaviour and Immunity

The effect of truncated infections with Ostertagia ostertagi on the development of acquired resistance in calves

Antler asymmetry and immunity in reindeer

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