Skin Deep: Uncovering the Early Events of Crimean-Congo Hemorrhagic Fever Virus at the Tick-Host-Virus Interface

Crimean-Congo hemorrhagic fever virus (CCHFV) is transmitted predominantly through the bite of infected Hyalomma ticks, yet the earliest events at the vector-host-virus interface in human skin remain largely undefined. This review synthesizes current knowledge of human cutaneous structure and immunity, tick feeding biology, and salivary immunomodulation to propose how local skin responses may shape systemic outcomes of CCHFV disease. We detail the roles and permissiveness of major skin-resident and infiltrating cell types, including keratinocytes, melanocytes, Langerhans cells, dermal dendritic cells, monocytes/macrophages, fibroblasts, granulocytes, T cells, B cells, NK cells, and innate lymphoid cells, in antiviral defense and as potential early targets or carriers of CCHFV. Emphasis is placed on how tick saliva components reprogram the cutaneous microenvironment, alter interferon, complement, inflammasome, and cytokine pathways, and may enable saliva-assisted transmission and viral dissemination from the dermis. We highlight mounting evidence from other arboviruses demonstrating that the skin can act as both a barrier and a major amplifying organ, and we extrapolate testable hypotheses on how early cutaneous immune dynamics might influence CCHFV severity and hemorrhagic manifestations. Finally, we outline key knowledge gaps that, if answered, may inform the development of vaccines and therapeutics that harness cutaneous immunity to block systemic spread.