The Reproductive Potential of Five Species of Coccidia of the Chicken as Demonstrated by Oocyst Production

Brackett, Sterling; Bliznick, Alexander

doi:10.2307/3273831

Cited by 53 publications

(31 citation statements)

References 3 publications

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“…The most remarkable result is the striking similarity between the model-derived graph in figure 3a and the results as published by Williams (2001), but also shown by others (Brackett and Bliznick 1952;Johnston et al 2001), who observed a crowding effect with increasing oocyst dose (figure 2). Two possible mechanisms have been suggested to cause the crowding effect: reduction in the availability of epithelial cells and acquired immunity (Williams 1998;Johnston et al 2001).…”

Section: (A) Biological Implicationssupporting

confidence: 84%

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A simple model for the within-host dynamics of a protozoan parasite

Klinkenberg

Heesterbeek

2005

Proc. R. Soc. B.

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The dynamics of parasite-host systems can be complicated if the parasite life cycle contains an obligatory environmental stage and if the hosts' immunity increases upon re-infection. The dynamics then greatly depend on the relation between infection history and parasite uptake and excretion of individual hosts. In an effort to better understand such systems, we study Eimeria spp. in chickens as our model. In this paper we take a first step and study the within-host dynamics of Eimeria spp., transmitted through oocysts in the environment, with a mathematical model for the parasite life cycle in discrete time, interacting with a single variable describing the immune response. The model can explain various types of oocyst input-output behaviour as described in previous experiments, in particular the characteristic crowding effect, which causes a decreasing oocyst production with increasing single dose oocyst uptake. Oocyst excretion during constant oocyst uptake (trickle infection) and the immunizing effect of single and trickle infections also appears in accordance with published experiments. The model seems a good description of oocyst input-output behaviour in individual hosts; it provides a solid basis for the study of between-host dynamics, where individuals interact in a common environment, thereby affecting their own and each other's infection pattern.

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Section: (A) Biological Implicationssupporting

confidence: 84%

“…If the immune effector function f were a negative exponential instead of a hyperbolic function, the graph would decrease much faster, which is not supported by experimental data (Brackett & Bliznick 1952;Johnston et al 2001;Williams 2001).…”

Section: Model Analysismentioning

confidence: 79%

A simple model for the within-host dynamics of a protozoan parasite

Klinkenberg

Heesterbeek

2005

Proc. R. Soc. B.

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“…Cross resistance between polyether ionophores is well documented (Weppelman et al, 1977;Voeten, 1989). Nonetheless, caution must be exercised when using oocyst counts as a means of evaluating anticoccidial efficacy (Reid, 1975) as factors such as initial infection level, Eimeria species involved, reproduction potential, crowding effect and acquired immunity influence the oocyst output (Brackett & Bliznick, 1952;Williams, 1973;Henken et al, 1994;Graat et al, 1996;Williams, 2001). …”

Section: Discussionmentioning

confidence: 99%

Coccidial infections in commercial broilers: epidemiological aspects and comparison ofEimeriaspecies identification by morphometric and polymerase chain reaction techniques

et al. 2008

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The objective of this study was to add to existing knowledge of the epidemiology and the aetiology of coccidial infections in commercial broiler flocks. Polymerase chain reaction (PCR) and morphometric identification of the Eimeria species were compared as means of differentiation in the field samples of faeces and litter. For morphometry, the Eimeria species were categorized into three groups based on lengths of the oocysts. Two random samples of commercial broilers were studied, one during 2000/01 and the other during 2003/04. The prophylactic regime (in-feed narasin), husbandry and methods applied were broadly the same for both subpopulations. Coccidial infection prevalence increased from approximately 45% to approximately 75% during this period, but infection levels (oocysts per gram of faeces) did not significantly change. There were substantial geographical differences in both prevalence and infection levels. A change in Eimeria species profile occurred during the study period. Five Eimeria species were identified at slaughter, by PCR targeting the ITS-1 region of the genome; Eimeria acervulina (100%), Eimeria tenella (77%), Eimeria maxima (25%), Eimeria praecox (10%) and Eimeria necatrix (2%). PCR and morphometric tentative identification were in complete agreement in only 49% of the cases.

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“…The different infection patterns of the two intracellular parasites may reflect the response of the host immune system to co-infection. As C. parvum tends to be highly immunogenic and prolific (2 auto-infective stages), high levels of infection in lambs in 2001 may have suppressed levels of Eimeria species oocyst shedding either due to immuno-cross-reactivity (Lorenzo et al 1998) or as a result of the so called ' crowding effect ' as demonstrated in Eimeria infection in chickens where very high levels of infection result in a decrease in oocyst output due to a combination of competition between and within species and sloughing off of epithelial cells (Brackett and Bliznick, 1952 ;Williams, 1973).…”

Section: Associations With Yearmentioning

confidence: 99%

Epidemiology of parasitic protozoan infections in Soay sheep (Ovis ariesL.) on St Kilda

et al. 2006

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The feral Soay sheep (Ovis aries L.) population on Hirta, St Kilda, is host to a diverse component parasite community, but previous parasitological studies of the population have only focussed on the metazoan species. This paper reports the first epidemiological study of the protozoan species comprising Cryptosporidium parvum, Giardia duodenalis and 11 species of Eimeria in Soay sheep across 3 years of varying host population density. Prevalence and intensity of almost all species of protozoa significantly decreased with host age, with the exception of E. granulosa, which increased in prevalence with host age. The prevalence of C. parvum appeared to vary positively with host population density but that of G. duodenalis did not vary significantly with density. Most species of Eimeria showed a distinct lag in infection level following the host population crash of 2002, taking up to 2 years to decrease. Mixed Eimeria species intensity and diversity were highest in 2002, a year of low host density. Parasite diversity decreased with host age and was higher in males. There were 5 positive pair-wise associations between protozoa species in terms of prevalence. The results of this study highlight the potential for protozoal infection to shape the evolution of parasite resistance in wild host populations harbouring diverse parasite species.

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The Reproductive Potential of Five Species of Coccidia of the Chicken as Demonstrated by Oocyst Production

Cited by 53 publications

References 3 publications

A simple model for the within-host dynamics of a protozoan parasite

A simple model for the within-host dynamics of a protozoan parasite

Coccidial infections in commercial broilers: epidemiological aspects and comparison ofEimeriaspecies identification by morphometric and polymerase chain reaction techniques

Epidemiology of parasitic protozoan infections in Soay sheep (Ovis ariesL.) on St Kilda

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