Forecasting the incidence of parasitic gastroenteritis in lambs in England and Wales

Ollerenshaw, C. B.; Graham, EG; Smith, LP

doi:10.1136/vr.103.21.461

Cited by 13 publications

(4 citation statements)

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“…Fourth, although there is a tendency to explain the dynamical behaviour of parasite populations in livestock almost wholly in terms of the weather (Gettinby, Bairden, Armour & Benitez-Usher, 1979;Ollerenshaw, Graham & Smith, 1978), year to year fluctuations in parasite numbers are at least partially explicable in terms of natural regulatory processes (for example, the effect of the host response to infection on parasite survival and fecundity).…”

Section: Discussionmentioning

confidence: 99%

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

et al. 1987

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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.

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Section: Discussionmentioning

confidence: 99%

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

et al. 1987

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“…Moisture is emphasized for Fasciola hepatica Leimbacher, 1978;Hope Cawdery, Gettingby and Grainger, 1978;Ross, 1978;WiUiamson and Wilson, 1978). Temperature is emphasized for Nematodirus balms (Gibson and Smith, 1978;Ollerenshaw, 1974, Ollerenshaw andSmith, 1966;Ollerenshaw, Graham and Smith, 1978;Thomas, 1974Thomas, , 1978Thomas and Starr, 1978).…”

Section: Moisture and Temperaturementioning

confidence: 98%

Weather and the ecology of bursate nematodes

Levine

1980

Int J Biometeorol

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ABSTRACT. --The fr6e-living stages of bursate nematodes are affected in different ways by meteorological factors. The eggs and 1st and 2nd stage larvae live in the feces, and these factors act on them through the feces. The embryo in the egg is protected by the eggshell. The 1st and 2rid stage larvae feed on micro-organisms, and are affected by the species of microorganisms and their metabolic products. The 3rd stage, infective larvae do not feed but leave the feces and migrate onto the vegetation, where they are more directly affected by meteorological factors than the earlier stages. They are partially protected by their sheath. The degree day concept can be used to predict the length of time required for development to the infective stage. Under constant conditions at 100% relative humidity and 20-35 ° C, Trichos}rongylus colubriformis requires 90-115 degree days (temperature times number of days) to reach the infective stage, and Haemonchus contortus requires 95-144 degree days. The great majority of eggs dies within the 1st day after reaching pasture, altho most of them would develop to the infective stage in the laboratory. Only 0.03% of H. contortusand T. colubriformis eggs placed on pasture were recovered from the vegetation as infective larvae. When larvae of 1t. contortus were placed on pasture, 1.6% (about 50 times as many but still only aout 1/30 of their potential) were later recovered. The cause of this die-off is unknown. Two types of potential worm burden prediction must be made-general and specific. The former can be made on the basis of temperature and moisture, but the latter requires information on many modifying factors.

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“…Several such indices (for several parasite species) were created and tested (e.g. 30, 38, 39, 63, 64), but the Mt index was perhaps the most influential. It was simply rainfall less evapo-transpiration, multiplied by the number of rain days calculated for May, June and July (together with a simple adjustment for location).…”

Section: Why Build Models At All?mentioning

confidence: 99%

Models of macroparasitic infections in domestic ruminants: a conceptual review and critique

Smith¹

2011

Rev. Sci. Tech. OIE

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Summary A mathematical model is just a means of representing and manipulating something that would not otherwise be accessible. Decision theorists argue that a right decision is one that makes the best use of the available information and using mathematical models of infectious and parasitic disease can help make sure the decision-makers do just that. Seen in this light, models are simply aids to thought – and thus, by definition, good models are useful. This paper deals with the history of mathematical models of parasitic infections of domestic ruminants. It is argued that the early simple forecasting models were very successful, and, although the more complicated models that were constructed to improve the resolution of the forecasts were mostly failures, the experience gained generated a slew of useful, robust models that are still valuable decision-making tools.

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Forecasting the incidence of parasitic gastroenteritis in lambs in England and Wales

Cited by 13 publications

References 0 publications

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

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

Weather and the ecology of bursate nematodes

Models of macroparasitic infections in domestic ruminants: a conceptual review and critique

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