Bluetongue: Vector Surveillance in Austria
After major outbreaks in the Netherlands, Germany and Belgium in 2006, bluetongue disease (BTD), which had long since been known from South Africa and the Mediterranean region, became an important issue in Central Europe. This infectious disease is caused by the bluetongue virus (BTV) and afflicts ruminants, mainly sheep and cattle, but also goats and wild ruminants. The virus itself needs biting midges (Diptera, Ceratopogonidae) of the genus Culicoides as vectors. About fifty Culicoides species worldwide are known to transmit various diseases.
During June 2007 and June 2010, a project on vector surveillance was commissioned and funded by the Federal Ministry of Health (Bundesministerium für Gesundheit, BMG). It was carried out by the Austrian Agency for Health and Food Safety (Österreichische Agentur für Gesundheit und Ernährungssicherheit, AGES) and the Natural History Museum Vienna (NHM) with the objective of investigating distributional and seasonal patterns of Culicoides in Austria.
In order to assure a homogeneous distribution of sampling sites in Austria, we sampled a grid pattern of 40 km x 40 km, with one sampling site for each grid cell. Sampling sites were chosen according to the following criteria:
- minimum stock of 10 animals (cattle, sheep or goats)
- moderate altitude (alpine regions above 1200 m were excluded)
- ready cooperation of farmer
Grid cells in alpine regions and those that only partly cover Austrian territory were not considered.
Sampling was carried out using blacklight traps from sunset to sunrise once a week. Traps were set up in weather-sheltered areas in close vicinity to the stables. In addition, meteorological data, such as minimum and maximum temperature, wind force and precipitation, were collected.
In the course of the study (June 2007 to June 2010), about 7,500 samples with 12.6 m specimens of 30 Culicoides species were analysed; 19 identified species represented new records for Austria. When adding historical data (from literature and the NHM collection) to this number, there is a total of 32 species of Culicoides currently known from Austria.
In 2008 and 2009, we recorded the highest abundance (average specimens per sample) from Styria and Burgenland and the lowest from Vorarlberg. Avaritia was the dominant subgenus in most of the samples; only in some districts of Lower Austria species of the subgenus Culicoides were equally abundant. In Burgenland (esp. Neusiedl am See), a surprisingly high number of species of the subgenus Monoculicoides was recorded.