Comparing two predictive risk models for nematodirosis in Great Britain

Abstract

Background: Nematodirus battus infection is a major health concern in lambs. Development and hatch of infective larvae on pastures is temperature dependent, making model‐based risk forecasting a useful tool for disease control. Methods: Air and 30 cm soil temperature‐based risk models were used to predict hatch dates using meteorological data from 2019 and compared to infection dates, estimated from the first appearance of N. battus eggs, on 18 sheep farms distributed across Great Britain. Results: The air temperature model was more accurate in its predictions than the soil temperature model on 12 of the 18 farms, but tended to predict late hatch dates in the early part of the season. Conclusion: Overall, the air temperature model appears the more appropriate choice for predicting N. battus peak hatch in the UK in terms of accuracy and practicality, but some adjustment might be needed to account for microclimatic variations at the soil–air interface.

Understanding the role of wild ruminants in anthelmintic resistance in livestock

“…For instance, Nematodirus battus is a highly pathogenic small intestine nematode for sheep which can also infect deer [ 74 , 75 ]. Well-validated air and soil temperature models are frequently used to predict infection in sheep [ 76 ], but as the nematode is not obviously pathogenic in wild ruminants, nor are wild ruminants thought to be significant sources of spill-over infections for livestock, there is little stimulus to use the model for wild hosts. With increasing AR, however, and the lack of information about transmission between wild and domestic hosts, expanding climate-driven helminth models for use in wildlife could be important.…”

Changing patterns of Nematodirus battus infection

“…Risk assessment programmes based on temperature data from weather stations around the UK (for example, https://www.scops.org.uk/forecasts/nematodirus-forecast/) have been developed to estimate the likelihood of nematodirosis occurrence in the spring at regional levels. The first models developed in the 1970s used mean soil temperatures, but later work has shown models that use air temperature to be more accurate in predicting the peak hatch of N. battus L3 (Hopkinson et al, 2021). These data, along with a history of grazing of the fields by young lambs during the previous year, are used to determine the need for and timing of anthelmintic treatments, but can lack sensitivity at individual farm level.…”

Forecasting the timing of N battus eggs hatching

“…I WAS interested to read the original research study by Hopkinson and others on the accuracy of forecasting nematodirus infection 1 . The ‘nematodirus forecast’ has been a valuable aid to sheep farmers and will increase in value as more accurate predictions are made.…”