Field study on the epidemiology and pathogenicity of different isolates of bovine Ostertagia spp

Saqur, I. Al; Armour, J.; Bairden, K.; Dunn, A. M.; Jennings, F. W.; Murray, M.

doi:10.1016/s0034-5288(18)32308-7

Cited by 6 publications

(2 citation statements)

References 8 publications

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“…However, the net impact on PC levels can be considered to be small due to counteracting mechanisms. For example, heavy rainfall increases larval mortality and accelerates the passage of larvae from pasture downward into the soil reservoir (Al Saqur et al 1982 ; Gruner et al 1982 ; Grenfell et al 1986 ), whilst increased moisture helps the transmission of larvae from fecal pats to herbage by translocation and by splash dispersal (Grønvold and Høgh-Schmidt, 1989 ; Stromberg, 1997 ). Only temperature was accounted for in the model, as being the most influential climatological feature on PC levels (Stromberg, 1997 ).…”

Section: Discussionmentioning

confidence: 99%

A stochastic model to investigate the effects of control strategies on calves exposed toOstertagia ostertagi

et al. 2016

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SUMMARYPredicting the effectiveness of parasite control strategies requires accounting for the responses of individual hosts and the epidemiology of parasite supra- and infra-populations. The first objective was to develop a stochastic model that predicted the parasitological interactions within a group of first season grazing calves challenged by Ostertagia ostertagi, by considering phenotypic variation amongst the calves and variation in parasite infra-population. Model behaviour was assessed using variations in parasite supra-population and calf stocking rate. The model showed the initial pasture infection level to have little impact on parasitological output traits, such as worm burdens and FEC, or overall performance of calves, whereas increasing stocking rate had a disproportionately large effect on both parasitological and performance traits. Model predictions were compared with published data taken from experiments on common control strategies, such as reducing stocking rates, the ‘dose and move’ strategy and strategic treatment with anthelmintic at specific times. Model predictions showed in most cases reasonable agreement with observations, supporting model robustness. The stochastic model developed is flexible, with the potential to predict the consequences of other nematode control strategies, such as targeted selective treatments on groups of grazing calves.

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Section: Discussionmentioning

confidence: 99%

A stochastic model to investigate the effects of control strategies on calves exposed toOstertagia ostertagi

et al. 2016

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“…Ostertagia mossi has yet to be reported from sheep or cattle; however, it could be easily mistaken for 0. leptospicularis. This latter species is considered pathogenic in Cervus elaphus L. (see Dunn, 1983) and has been implicated in ostertagiasis in cattle in the United Kingdom and New Zealand (Al Saqur et al, 1982a, 1982b, 1984Sulger Btiel et al, 1984;Bisset et al, 1984). Although disease has not been associated with infections of O. leptospicularis in Oregon or Montana, reports from the United Kingdom suggest the potential for ostertagiasis due to this species.…”

Section: Discussionmentioning

confidence: 99%

Comparative morphology of Ostertagia mossi and Ostertagia dikmansi (trichostrongylidae) from Odocoileus virginianus and comments on other Ostertagia spp. from the Cervidae

1993

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The synlophes of Ostertagia mossi Dikmans, 1931 and O. dikmansi Becklund &Walker, 1968 were found to be identical supporting recognition of these as the major and minor morphotypes, respectively, of a putative species pair within the Ostertagiinae. The cervical synlophe included three narrowly spaced, continuous, parallel ridges laterally and three parallel but more widely spaced ridges in the dorsal and ventral fields (Type II and Type A patterns, respectively). The disposition of the synlophe in conjunction with a long oesophageo-intestinal valve, and attributes of the genital cone and spicules are characteristics shared among other Ostertagia spp. from cervids in the Holarctic region that allow recognition of a species group morphologically distinct from the Ostertagiinae of domestic ruminants. The morphological similarity of O. mossi/O, dikmansi, O. leptospicularis Assadov, 1953/O. kolchida Popova, 1937 and O. gruehneri Skrjabin, 1929/O. arctica Mitzkewitsch, 1929 is substantial, but these species can be differentiated by small but constant differences in the synlophe and genital complex of males; females cannot be easily distinguished. The morphological similarity of this cryptic complex of species and their relatively restricted distribution among cervids suggests a coevolutionary history for hosts and parasites in the Holarctic region.

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Experimental studies on the interaction between infections ofOstertagia leptospicularis and other bovineOstertagia species

et al. 1984

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Experimental infections of calves were carried out with either isolates of predominantly Ostertagia ostertagi, pure O. leptospicularis or a mixed isolate of equal numbers of both these species. The total worms established on day 21 for the mixed species from a total inoculum of 100 000 infective larvae, was 1.2 times greater than from 100 000 larvae of the O. ostertagi isolate and 3.3 times that of the pure O. leptospicularis isolate. The increased establishment in the mixed inoculum referred to both O. ostertagi and O. leptospicularis (days 17 and 21). These differences were both highly significant (P less than 0.01). The severity of the pathological changes was also greater in the mixed infections. It is suggested that these findings must be taken into account when control measures involving alternate grazing of sheep and cattle are being employed.

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Field study on the epidemiology and pathogenicity of different isolates of bovine Ostertagia spp

Cited by 6 publications

References 8 publications

A stochastic model to investigate the effects of control strategies on calves exposed toOstertagia ostertagi

A stochastic model to investigate the effects of control strategies on calves exposed toOstertagia ostertagi

Comparative morphology of Ostertagia mossi and Ostertagia dikmansi (trichostrongylidae) from Odocoileus virginianus and comments on other Ostertagia spp. from the Cervidae

Experimental studies on the interaction between infections ofOstertagia leptospicularis and other bovineOstertagia species

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