Transmission and control of African horse sickness in The Netherlands: a model analysis.
Authors: Backer Jantien A, Nodelijk Gonnie
Journal: PloS one
Summary
# African Horse Sickness Control: Lessons from Dutch Risk Modelling Backer and Nodlijk developed a vector-host transmission model to evaluate how African horse sickness (AHS) would establish and spread in the Netherlands, using bluetongue's recent arrival as a cautionary precedent and incorporating established knowledge of viral infection dynamics and Culicoides biology. The model revealed that introduction timing relative to the midge season is critical, but the vector-to-host ratio—which varies considerably across regions—emerges as the dominant factor determining epidemic severity, with temperature acceleration and horse density also playing significant roles. Encouragingly, AHS presents a more controllable epidemiological profile than bluetongue due to its shorter infectious period in horses (approximately 7–10 days), distinctive clinical signs enabling rapid identification, and the presence of naturally refractory equine populations. The authors advocate for a tiered control strategy centred on culling clinically affected horses, targeted midge suppression in affected premises, bite protection for neighbouring herds, and strategic vaccination of more distant operations—provided strict transport biosecurity prevents mechanical spread. However, the critical evidence gap remains the vector competence and host preference of temperate Culicoides species, knowledge essential for refining control protocols and predicting whether AHS would sustain transmission in northern European conditions.
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Practical Takeaways
- •Monitor Culicoides vector populations and midge activity seasonally—introduction timing during peak vector season dramatically increases disease spread risk
- •Implement midge-exclusion practices (shelter, netting) in neighboring herds when cases are detected, as this is more feasible than controlling vectors across large areas
- •Coordinate with veterinary authorities on rapid vaccination strategies for distant herds before disease establishes, since early detection window is your advantage over bluetongue
Key Findings
- •Vector-to-host ratio is the most critical factor determining AHS spread, with high variability across geographic regions
- •Higher ambient temperature accelerates epidemic progression while higher horse density increases epidemic extent
- •AHS is expected to spread less easily than bluetongue due to short infectious period in horses and obvious clinical signs allowing early detection
- •Early detection enables targeted control measures including euthanasia of severely affected horses, vector control, and strategic vaccination