Crimean-Congo hemorrhagic fever cases in the North of Iran have three distinct origins.

An on-going surveillance program on Crimean-Congo haemorrhagic fever virus (CCHFV) in Iran has been launched since 2000. An outbreak of CCHF occurred in northern Iran between June and July 2015. Three cases were involved in this outbreak. One patient died after admission to hospital, and the others were treated successfully. Phylogenetic analysis showed that three sequences obtained from Iranian patients grouped within clade IV (Asia-1), clade V (Europe) and clade VI (Greece). The partial sequence of the strain Noshahr59 (KT588642) showed the highest similarity with other strains isolated from Russia, Kosovo and Turkey (Clade V, Europe). The genome sequence of the strain Chalous65 (KT588640) showed 100% homology to the strain AP29 isolated from Greece (DQ211638). The genome sequence of the strain Noshahr43 (KT588641) showed 88% similarity to the Pakistani and previously reported Iranian strains (AF527810, AJ538198, AY366379 and AY366373). These data support previous studies, which showed a distinct similarity between Iranian S segments of CCHFV strains with other strains within clade IV (Asia-1) and clade V (Europe). In addition, clade VI was detected for the first time in Iran. Moreover, strain Chalous65 with similar genetic characteristics to strain AP29 from Greece was isolated from a fatal human case.