engleski

Entomological surveillance of vectors of Bluetongue virus in Croatia

Objectives: Bluetongue disease was reported in sheep in Croatian Mediterranean region (Dubrovnik-Neretva County) for the first time in 2001. Since then Culicoides has been regularly monitored. The aim of this study is to analyze vectors and to assess the vector distribution and seasonal abundance as factors in predicting disease incidence and spread. Material and methods: Samples were collected at 26 sites in nine Croatian counties, with special focus on the population of vectors in the Mediterranean region. Vector abundance was determined by light traps on selected farms. Culicoides species were morphologically identified. The distribution and seasonal abundance of Culicoides were also analysed. Results: 46.709 adult insects of the Culicoides genus were identified, out of which 40.21 % belonged to the Obsoletus group and 51.50 % to the Pulicaris group. Female adults predominated in both groups. The highest rate of nulliparous (more than 70 %) and the lowest rate of gravid females (les than 1 %) was recorded in both groups. Out of all vector risk areas, the highest number of both vectors was found in the Mediterranean region. In summer, significantly higher number of vectors of the Obsoletus group (9.16 %, CI 95 % 6.72-11.68 % per sample) than of the Pulicaris group (3.66 %, CI 95 %, 1.90 - 5.43 % per sample) was found, while in autmn Pulicaris vector was dominant (39.72 %, CI 95 %, 29.64–49.90 % per sample). Culicoides immicola was not identified at any study sites. Conclusions: In Croatia, bluetongue virus can be transmitted by multiple Culicoides vectors, belonging to the Obsoletus group and the Pulicaris group. Significant differences in seasonal abudance were found. Relevance: The results can serve as input data for creating a national targeted surveillance program taking into consideration both spatial and temporal distribution of vectors.

Culicoides, age granding, distribution, seasonal abundance, Croatia

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