By Rick van der Heijden
Abstract:
The past ten years an increase of zoonotic diseases (diseases caused by infectious agents that can be transmitted between animals and humans) occurred in Europe. Bluetongue disease is an infectious, non-contiguous, arthropod-borne viral disease, mostly of sheep, but also of other ruminants. An important factor in the distribution of BlueTongue Virus (BTV) worldwide is the availability of suitable vectors, usually biting midges of the species Culicoides. Wherever the required vectors are present, BTV can become endemic.
The objective of this thesis is to make a spatial risk analysis for Bluetongue in the Netherlands, determining which areas are susceptible for new epidemics. Literature research is used to identify vector species and host species occurring in the Netherlands. A spatial model, using vectorial capacity, is used to identify the areas in the Netherlands where sheep and other cattle live closely to populations of bluetongue vectors. Data on weather, the natural habitat of the bluetongue vectors, as well as data on different animal farms will be used.
Six species of Culicoides are identified as potential vectors. Ovine and bovine hosts are omnipresent in the Netherlands.
Temperature is a key factor in the process of Bluetongue development. A rise in temperature will lead to higher risks. During May till October temperature is high enough to cause a risk for Bluetongue outbreaks, with a peak in August.
Besides temperature few other factors can have a raising effect on the vectorial. The presence of peat vegetation and of pig farms can both heighten the risk of Bluetongue.