2 research outputs found
Spatial analysis of bluetongue cases and vaccination of Swiss cattle in 2008 and 2009
Bluetongue (BT) is a vector-borne viral disease of ruminants. The infection is widespread globally with major
implications for international animal trade and production. In 2006, BT virus serotype 8 (BTV-8) was encountered in Europe
for the first time, causing extensive production losses and death in susceptible livestock. Following the appearance of BTV-
8 in Switzerland in 2007, a compulsory vaccination programme was launched in the subsequent year. Due to social factors
and difficulties to reach animals on high pasture, the regional vaccination coverage varied across the country in both 2008
and 2009. In this study, the effect of vaccination on the spatial occurrence of BTV-8 and the associated relative disease risk
in Switzerland in 2008 and 2009 were investigated by a spatial Bayesian hierarchical approach. Bayesian posterior distributions
were obtained by integrated nested Laplace approximations, a promising alternative to commonly used Markov
chain Monte Carlo methods. The number of observed BTV-8 outbreaks in Switzerland decreased notably from 2008 to
2009. However, only a non-significant association between vaccination coverage and the probability of a spatial unit being
infected with BTV-8 was identified using the model developed for this study. The relative disease risk varied significantly
across the country, with a higher relative risk of BTV-8 infection in western and north-western Switzerland where environmental
conditions are more suitable for vector presence and viral transmission. Examination of the spatial correlation
between disease occurrence, control measures and associated ecological factors can be valuable in the evaluation and development
of disease control programmes, allowing prioritisation of areas with a high relative risk of diseas