SCREENING FOR CRIMEAN-CONGO HEMORRHAGIC FEVER VIRUS IN TICKS COLLECTED IN SARDINIA (ITALY) AND TUNISIA

Climate change is promoting the spread of ticks and tick-borne viruses, leading to the diffusion of new pathogens such as the Crimean-Congo hemorrhagic fever virus (CCHFV). In the last decade, CCHFV has colonized Southwest Europe, as evidenced by human cases reported in Spain and the detection of CCHFV in ticks collected in Southern France and Corsica. In Italy, sporadic detection of CCHFV-positive ticks has been reported only in those collected from migratory birds. Sardinia, an Italian island close to Corsica, is a site of intense passage for birds migrating along major routes between Africa and Europe, thus representing a location potentially exposed to the risk of CCHFV introduction. Similarly, Tunisia, located on the Mediterranean Sea, represents a key area for migratory bird stopovers. There is evidence of CCHFV circulation in camels in Tunisia, but viral RNA was detected just one time in a Hyalomma impeltatum tick detached by a camel [1]. This study was designed to determine the presence of CCHFV in ticks collected in Sardinia and Tunisia and evaluate the potential phylogenetic correlations. A total of 227 ticks were collected from different districts of Sardinia and 242 ticks from various areas of Tunisia. Ticks were collected from domestic animals, wild mammals, and vegetation in Sardinia, and from camels in Tunisia. Morphological identification of ticks was performed using taxonomic keys. Each tick was homogenized, and nucleic acids were extracted using the Maxwell® RSC48 Instrument (Promega). One aliquot was subject to one-step real-time RT-PCR for the detection of CCHFV, using AgPath-ID™ One-Step RT-PCR Kit (Thermo Scientific). Results did not show the presence of CCHFV in ticks from Sardinia, while 5 Hyalomma spp ticks from Tunisia collected from two camels were positive. Most of the CCHFV S segment sequences showed 91-98% identity to reported sequences of Orthonairovirus haemorrhagiae (CCHFV) strain ARD407551 segment S nucleoprotein gene (GenBank: PP894731.1) detected in Hyalomma impeltatum from Senegal. Although no CCHFV-positive ticks were detected in Sardinia, considering the rapid expansion of CCHFV in European countries over the last decade and the presence of the virus in ticks collected in Tunisia, a key territory for bird migratory routes, surveillance activity should be performed to identified new sites of virus circulation in order to adopt appropriate public health measures.