Authors: Storms Julia, Wirth Anna, Vasiliadis Danae, Brodard Isabelle, Hamann-Thölken Antje, Ambros Christina, Moog Udo, Jores Jörg, Kuhnert Peter, Distl Ottmar
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Dichelobacter nodosus causes significant disease in sheep flocks across Germany, with carriers often showing no clinical signs—a finding that has important implications for biosecurity and flock management. This field study screened over 9,000 sheep from 207 German flocks using standardised footrot scoring and interdigital swab sampling analysed via real-time PCR to distinguish benign from virulent strains. Nearly 43% of individual animals tested positive for the pathogen, yet only 6.13% displayed clinical underrunning (scores 3–5); more striking still, almost half the flock showed clinically healthy feet despite harbouring the organism, with 1,117 such animals testing positive—predominantly (90.35%) for virulent strains. The predominance of virulent D. nodosus in asymptomatic carriers means visual inspection alone cannot reliably identify infected sheep, creating a reservoir for persistent flock infection and transmission. For practitioners managing footrot in German sheep populations, these results underscore the value of targeted PCR screening and strategic quarantine protocols, particularly when introducing stock or managing mixed-strain flocks, since relying on clinical assessment will miss the majority of infected animals.
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Practical Takeaways
- •Clinical inspection alone is insufficient for footrot diagnosis—nearly half of infected sheep showed no clinical signs; PCR testing is necessary for accurate detection
- •Virulent D. nodosus strains predominate in German flocks (90.35% of positive samples), indicating high risk for severe disease progression and flock spread
- •Implement flock-level screening and management protocols, as prevalence varies widely between flocks; biosecurity and early detection in clinically healthy animals are critical for disease control
Key Findings
- •Mean prevalence of D. nodosus was 42.93% in German sheep at animal level across 207 flocks
- •6.13% of sheep showed clinical signs of footrot (underrunning of hoof horn, scores 3-5), while 47.85% had clinically healthy feet
- •Of 1,117 swabs from clinically healthy sheep that tested positive for D. nodosus, 90.35% contained virulent strains
- •59 flocks were D. nodosus-negative, 115 flocks had only virulent strains, and 7 flocks tested positive for benign strains only