Crimean-Congo hemorrhagic fever: An emerging threat in Europe.

Crimean-Congo hemorrhagic fever (CCHF), caused by Crimean-Congo hemorrhagic fever virus (CCHFV), is endemic in Africa, Asia, and Europe. However, CCHF epidemiology and epizootiology have been poorly defined in Europe. Here, we summarize the current knowledge of CCHFV distribution in (non-Russian) Europe, including countries previously not considered to be at risk. We collected data on CCHF cases, human/vertebrate animal anti-CCHFV seroprevalence, CCHFV vector (Hyalomma tick), and CCHFV isolation from ticks and classified countries into five risk levels using a One Health approach. From 1944 through Feb 2025, more than 2000 recorded CCHF cases were identified in Europe, mostly from southern/eastern countries/regions, primarily Bulgaria (at least 1623), Kosovo (at least 339), Ukraine (at least 336), Croatia (at least 200), Albania (at least 146), and Republic of Moldova (at least 60). Albania, Bulgaria, Greece, Kosovo, and Spain were categorized as level 1 (reported CCHF cases, presence of robust surveillance systems). North Macedonia, Portugal, and Ukraine/Crimea were assigned to level 2 (reported CCHF cases in the absence of robust established surveillance). Bosnia and Herzegovina, Croatia, France, Hungary, Italy, Montenegro, Republic of Moldova, Romania, and Slovenia were assigned to level 3 due to evidence of CCHFV circulation in absence of recent CCHF cases. Thirty-four countries were assigned to level 4 (presence of Hyalomma ticks) or level 5 (no data). This work provides information on CCHFV distribution and burden with list of at-risk areas to inform international and local public health agencies to establish or strengthen surveillance systems.