Emergence of Crimean-Congo hemorrhagic fever.

Crimean-Congo hemorrhagic fever (CCHF) is a life-threatening tick-borne infection in Africa and Eurasia. Although knowledge of epidemiology is increasing, the global extent and risk of infection is not well described. A niche-modeling framework has been used to map the global distribution of risk for CCHF based on analysis of human CCHF reports. The new risk maps provide a valuable starting point for understanding the zoonotic niche of CCHF. Migratory birds travelling across continents may also introduce CCHF to new areas through attached ticks. There is an overlap between CCHF endemic areas and breeding and wintering grounds of migratory birds.