Different patterns of faecal egg output following infection of Scottish Blackface lambs with Ostertagia circumcincta

Stear, M. J.; Bairden, K.; Bishop, Stephen; Duncan, J.L.; Karimi, Syafruddin; McKellar, Quintin; Murray, M.

doi:10.1016/0304-4017(94)00720-w

Cited by 16 publications

(8 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While pepsinogen levels have previously been reported to be an indicator of ostertagiosis in lambs (Balic et al, 2000;Davies et al, 2005;Lawton et al, 1996), another study of within-breed differences in gastrointestinal nematode resistance found that it is not significantly different between lambs with consistently high FEC and those whose FEC was consistently low (Stear et al, 1995a). Therefore, plasma pepsinogen concentration alone may be an unreliable indicator of ostertagiosis in the individual animal (Lawton et al, 1996).…”

Section: Discussionmentioning

confidence: 91%

Response to Teladorsagia circumcincta infection in Scottish Blackface lambs with divergent phenotypes for nematode resistance

McRae

Good

Hanrahan

et al. 2014

Veterinary Parasitology

View full text Add to dashboard Cite

The objective of this study was to identify Scottish Blackface lambs that were at the extremes of the spectrum of resistance to gastrointestinal nematodes and characterise their response to an experimental nematode challenge. Lambs (n = 90) were monitored for faecal egg count (FEC) (2 samples from each of 2 independent natural infections). The most resistant (n = 10) and susceptible (n = 10) individuals were selected and challenged with 30,000 Teladorsagia circumcincta larvae (L3) at 9 months of age. Response to infection was monitored by measuring FEC, plasma pepsinogen, serum antibodies against nematode larval antigens and haematology profile, until necropsy at 71 days post infection. Worm burden, worm fecundity and the level of anti-nematode antibodies in abomasal mucosa were determined at necropsy.FEC was consistently higher in susceptible animals (P < 0.05), validating the selection method. Worm fecundity was significantly reduced in resistant animals (P = 0.03). There was also a significant correlation (r = 0.88; P < 0.001) between the number of adult worms and FEC at slaughter. There was no effect of phenotype (resistance/susceptibility) on plasma pepsinogen or on haematology profile.Phenotype had a significant effect on the level of anti-nematode IgA antibodies in serum (P < 0.01), reflecting a higher peak in resistant animals at day 7 post infection.It is concluded that significant variation in the response to gastrointestinal nematode challenge exists within the Scottish Blackface population with resistant animals displaying significantly lower FEC, lower worm fecundity and higher concentration of anti-nematode IgA antibodies in serum.-4 -

show abstract

Section: Discussionmentioning

confidence: 91%

Response to Teladorsagia circumcincta infection in Scottish Blackface lambs with divergent phenotypes for nematode resistance

McRae

Good

Hanrahan

et al. 2014

Veterinary Parasitology

View full text Add to dashboard Cite

show abstract

“…Herbage density, H , was given the value 1200 kg ha −1 (Waller et al 1981). For the parameters relating directly to the parasite, we used a value of 21 days for the development time from egg to infective stage, u (Urquhart et al 1996), and a value of 14 days for the pre-patent period, j (Stear et al 1995 a ). Stocking density is one parameter in the model that we consider free, in that it is not dictated by biological constraints but rather by farming practice.…”

Section: Methodsmentioning

confidence: 99%

“…A value of 35 lambs ha − 1 was used for the stocking density, D. Herbage density, H, was given the value 1200 kg ha − 1 (Waller et al 1981). For the parameters et al 1996), and a value of 14 days for the pre-patent period, j (Stear et al 1995a). Stocking density is one parameter in the model that we consider free, in that it is not dictated by biological constraints but rather by farming practice.…”

Section: Comparison With Observed Faecal Egg Countsmentioning

confidence: 99%

A mechanistic model of developing immunity to Teladorsagia circumcincta infection in lambs

2010

View full text Add to dashboard Cite

Acquired immunity influences the severity of parasitic disease, but modelling the effects of acquired immunity in helminth infections has proved challenging. This may be due to a lack of suitable immunological data, or to the perceived complexity of modelling the immune response. We have developed a model of T. circumcincta infection in domestic sheep that incorporates the effects of acquired immunity on parasite establishment and fecundity. A large data set from commercially managed populations of Scottish Blackface sheep was used, which included relationships between IgA activity and worm length, and between worm length and fecundity. Use was also made of a recently published meta-analysis of parasite establishment rates. This realistic but simple model of nematode infection emulates observed patterns of faecal egg counts. The end-of-season faecal egg counts are remarkably robust to perturbations in the majority of the parameters, possibly because of priming of the immune system early in the season, reducing parasite establishment and growth and, therefore, faecal egg counts. Lowering the amount of early infection leads to higher end-of-season egg counts. The periparturient rise in egg counts in ewes appears to have an important role in supplying infection for the priming of the immune response. This feedback in the immune priming suggests that nematode infections may be difficult to eliminate.

show abstract

“…The host immune system is thought to play an important role in mediating many types of density‐dependent mechanisms (Tallis & Leyton 1966; Woolhouse 1992; Stear et al . 1995; Paterson & Viney 2002).…”

Section: Methodsmentioning

confidence: 99%

Density dependence and the control of helminth parasites

Churcher

Filipe

Basáñez

2006

Journal of Animal Ecology

View full text Add to dashboard Cite

Summary 1.The transient dynamics and stability of a population are determined by the interplay between species density, its spatial distribution and the positive and negative densitydependent processes regulating population growth. 2. Using the human-helminth parasite system as an example, we propose that the life-stage upon which negative density dependence operates will influence the rate of host reinfection following anthelmintic chemotherapy, and the likely success of control programmes. 3. Simple deterministic models are developed which highlight how a parasite species whose population size is down-regulated by density-dependent establishment will reinfect a host population at a faster rate than a species with density-dependent parasite fecundity. 4. Different forms of density dependence can produce the same equilibrium behaviour but different transient dynamics. Under-representing the nature and magnitude of density-dependent mechanisms, and in particular those operating upon establishing life-stages, may cause the resilience of the parasite population to a control perturbation to be underestimated.

show abstract

Different patterns of faecal egg output following infection of Scottish Blackface lambs with Ostertagia circumcincta

Cited by 16 publications

References 14 publications

Response to Teladorsagia circumcincta infection in Scottish Blackface lambs with divergent phenotypes for nematode resistance

Response to Teladorsagia circumcincta infection in Scottish Blackface lambs with divergent phenotypes for nematode resistance

A mechanistic model of developing immunity to Teladorsagia circumcincta infection in lambs

Density dependence and the control of helminth parasites

Contact Info

Product

Resources

About