Selective culling and the potential persistence of lumpy skin disease in cattle herds: insights from a mechanistic transmission model

Résumé fourni par la source

The first epidemic of lumpy skin disease (LSD) in France was detected in June 2025, with a total of 117 outbreaks recorded by the end of the year. This fast-spreading vector-borne disease of cattle prompted the implementation of strict control measures, including total depopulation of affected herds, resulting in the culling of more than 3500 cattle. Over the course of the epidemic, this measure became increasingly unacceptable, leading to major protests. To contribute to this veterinary public health debate, we present a mathematical model, accounting for both cattle and vector populations, that compares within-herd transmission dynamics under selective or total depopulation strategies, and different vector control scenarios. The selective depopulation strategies are modelled based on a bi-daily test-and-cull approach implemented upon detection of the first clinical case in an unvaccinated herd, with imperfect diagnostic tests capable of detecting infection in asymptomatic cattle under different assumptions of test sensitivity and of time from infection to detectability. Our model shows that the selective culling strategy is insufficient to control the spread of the disease in the absence of vector population control, with the entire herd eventually becoming infected. In the best-case scenario with highly sensitive and timely diagnostic tests and an 80% reduction of the vector population, still 75% (95% simulation interval: 26, 100) of the herd becomes infected. Assuming more realistic diagnostic tests (30% sensitivity for detecting subclinical animals within 2-3 days before the onset of infectiousness), the model predicts that 94% of the herd (95% simulation interval: 44, 100) eventually becomes infected, representing only a marginal improvement over a total depopulation strategy.

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