Genomic characterization of Crimean-Congo hemorrhagic fever virus in Hyalomma ticks from Cameroon highlights circulation of the Africa 3 lineage

Abstract Background Crimean-Congo Hemorrhagic Fever (CCHF) is a tick-borne zoonotic disease of growing public health importance worldwide. Despite its recognized presence in neighboring countries, data on the occurrence and molecular characteristics of Crimean-Congo Hemorrhagic Fever Virus (CCHFV) in ticks from Cameroon remain scarce. Methods Between March 2023 and November 2024, ticks were collected from cattle (originating from Adamawa and North regions) at the Ngaoundéré municipal slaughterhouse located in the Adamawa region of Cameroon. Specimens were morphologically identified, pooled, and screened for CCHFV RNA using real-time RT-qPCR. Minimum infection rates (MIR) were calculated. Positive samples underwent amplification and sequencing of the S and L genomic segments, followed by phylogenetic analysis using the Maximum Likelihood method (1,000 bootstrap replicates). Results A total of 299 adult ticks were collected from 50 cattle and grouped into 85 pools. Four pools tested positive for CCHFV RNA, all belonging to Hyalomma rufipes and H. nitidum . Partial sequences of the S (1,537 nt) and L (11,530 nt) segments were successfully obtained from one H. rufipes pool. Phylogenetic analysis placed both segments within genotype III (Africa 3). Conclusions This study provides the first molecular characterization of CCHFV from Hyalomma ticks collected from cattle in Cameroon. The findings underscore the need to integrate molecular surveillance and tick control into national One Health strategies to prevent potential spillover to humans.