Med. Weter. 76 (2), 71-76, 2020

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WIESŁAW NIEDBALSKI, ANDRZEJ FITZNER
Recent changes in the global distribution of arboviral infections in ruminants
The aim of this paper is to present the recent changes in the global distribution of bluetongue (BT) and epizootic hemorrhagic disease (EHD) in the world. Both of these arboviral infections are widespread in the territory of many continents. BT is currently endemic in many tropical, sub-tropical and temperate regions of the world (Africa, southern Asia, Australia, the Middle East, and the Americas), between latitudes 50°N and 35°S, during times of the year that are optimal for vector activity. In Europe, BTV serotypes 1, 2, 4, 8 and 16 are currently circulating in many regions of continent. The range of EHDV lies approximately between latitudes 35°S and 49°N. EHDV infection of wild and domestic ruminants has been reported in the America, Africa, Asia, Australia, the Middle East as well as some islands of the Indian Ocean. Recently it has also been recorded in cattle in countries surrounding the Mediterranean Basin including: Israel, Turkey, and northern African countries such as Morocco, Algeria and Tunisia. So far there has been no report of EHDV being present in Europe, but there has been only limited surveillance for subclinical infections in wild cervids. The global range of BT and EHD and their aetiological agents have changed remarkably in recent years, most notably with the incursion to Europe of multiple virus serotypes. The enormous genetic diversity of these orbiviruses can lead to the emergence of viruses with unique biological properties, such as a capacity for horizontal and vertical transmission. Reassortment of the genes of invasive orbiviruses with those viruses already present in environment has facilitated the successful introduction and spread of novel reassortant progeny between episystems.
Keywords: bluetongue (BT), epizootic hemorrhagic disease (EHD), global distribution, ruminants