Climate-driven changes to the spatio-temporal distribution of the parasitic nematode, Haemonchus contortus, in sheep in Europe.
Recent climate change has resulted in changes to the phenology and distribution of invertebrates worldwide. Where invertebrates are associated with disease, climate variability and changes in climate may also affect the spatio-temporal dynamics of disease. Due to its significant impact on sheep production and welfare, the recent increase in diagnoses of ovine haemonchosis caused by the nematode Haemonchus contortus in some temperate regions is particularly concerning. This study is the first to evaluate the impact of climate change on H. contortus at a continental scale. A model of the basic reproductive quotient of macroparasites, Q0 , adapted to H. contortus and extended to incorporate environmental stochasticity and parasite behaviour, was used to simulate Pan-European spatio-temporal changes in H. contortus infection pressure under scenarios of climate change. Baseline Q0 simulations, using historic climate observations, reflected the current distribution of H. contortus in Europe. In northern Europe, the distribution of H. contortus is currently limited by temperatures falling below the development threshold during the winter months and within-host arrested development is necessary for population persistence over winter. In southern Europe, H. contortus infection pressure is limited during the summer months by increased temperature and decreased moisture. Compared with this baseline, Q0 simulations driven by a climate model ensemble predicted an increase in H. contortus infection pressure by the 2080s. In northern Europe, a temporal range expansion was predicted as the mean period of transmission increased by 2-3 months. A bimodal seasonal pattern of infection pressure, similar to that currently observed in southern Europe, emerges in northern Europe due to increasing summer temperatures and decreasing moisture. The predicted patterns of change could alter the epidemiology of H. contortus in Europe, affect the future sustainability of contemporary control strategies, and potentially drive local adaptation to climate change in parasite populations.
School of Biological Sciences, Life Sciences Building, University of Bristol, Tyndall Avenue, Bristol, BS8 1TQ, UK.|School of Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol, BS40 5DU, UK.|Cabot Institute, University of Bristol, Cantocks Close, Bristol, BS8 1TS, UK.
Hannah
H
Rose
School of Environmental Sciences, University of Liverpool, Liverpool, UK.|Department of Epidemiology and Population Health, The Farr Institute @HeRC, University of Liverpool, Liverpool, L69 3GL, UK.
Cyril
C
Caminade
School of Biological Sciences, Life Sciences Building, University of Bristol, Tyndall Avenue, Bristol, BS8 1TQ, UK.|National Veterinary Research Institute, P.M.B. 01, Vom, Plateau State, Nigeria.
Muhammad Bashir
MB
Bolajoko
Animal & Grassland Research and Innovation Centre, Teagasc, Grange, Dunsanny, Co. Meath, Ireland.
Paul
P
Phelan
Department of Epidemiology and Population Health, Institute of Infection and Global Health, University of Liverpool, Leahurst, Neston, Cheshire, CH64 7TE, UK.
Jan
J
van Dijk
School of Environmental Sciences, University of Liverpool, Liverpool, UK.|Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Neston, UK.
Matthew
M
Baylis
Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Liverpool, L3 5RF, UK.
Diana
D
Williams
School of Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol, BS40 5DU, UK.|Cabot Institute, University of Bristol, Cantocks Close, Bristol, BS8 1TS, UK.
Eric R
ER
Morgan
D063147:Animal Distribution; D000822:Animal Husbandry; D000818:Animals; D050936:Basic Reproduction Number; D057231:Climate Change; D005060:Europe / Q000453:epidemiology; D006188:Haemonchiasis / Q000453:epidemiology* / Q000469:parasitology / Q000635:transmission / Q000662:veterinary*; D006189:Haemonchus / Q000502:physiology*; D008962:Models, Theoretical; D018570:Risk Assessment; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology* / Q000469:parasitology / Q000635:transmission; D013269:Stochastic Processes
Europe; Haemonchus contortus; Q0; adaptation; climate change; climate impact mitigation; distribution shift; gastrointestinal nematode; infection pressure