Spatial analysis of BSE cases in the Netherlands.
BACKGROUND
In many of the European countries affected by Bovine Spongiform Encephalopathy (BSE), case clustering patterns have been observed. Most of these patterns have been interpreted in terms of heterogeneities in exposure of cattle to the BSE agent. Here we investigate whether spatial clustering is present in the Dutch BSE case data.


RESULTS
We have found three spatial case clusters in the Dutch BSE epidemic. The clusters are geographically distinct and each cluster appears in a different birth cohort. When testing all birth cohorts together, only one significant cluster was detected. The fact that we found stronger spatial clustering when using a cohort-based analysis, is consistent with the evidence that most BSE infections occur in animals less than 12 or 18 months old.


CONCLUSIONS
Significant spatial case clustering is present in the Dutch BSE epidemic. The spatial clusters of BSE cases are most likely due to time-dependent heterogeneities in exposure related to feed production.
Heres
Lourens
L
Department of Bacteriology and TSEs, Central Veterinary Institute of Wageningen UR, Lelystad, The Netherlands. lourens.heres@vionfood.nl
Brus
Dick J
DJ
Hagenaars
Thomas J
TJ
D000821:Animal Feed; D000818:Animals; D002417:Cattle; D016000:Cluster Analysis; D016643:Encephalopathy, Bovine Spongiform / Q000453:epidemiology*; D009426:Netherlands; D013997:Time Factors