First report of Crimean-Congo Haemorrhagic Fever Virus exposure in Human and Livestock Populations, Centre region, Cameroon

Moréna GASPARINE^1,2*Armand Namekong-Fokeng^1,2Eva Lopez^1,2Stephanie Mvodo³Laurence Thirion²Archile Paguem³Remi N Charrel²Xavier De Lamballerie^2,4Alessandra Falchi^1,2

• ¹University of Corsica Pascal Paoli, Corte, France
• ²INSERM U1207 Virus émergents (UVE), Marseille, Provence-Alpes-Côte d'Azur, France
• ³University of Buea, Buea, Cameroon
• ⁴Centre National de Référence des Arbovirus, Marseille, France

Crimean-Congo haemorrhagic fever (CCHF) is a widespread, tick-borne viral infection present in many African countries. Its epidemiology and impact on public health remain poorly understood in Cameroon. The main objective of the current study was to investigate the circulation of CCHF virus (CCHFV) in ruminants (cattle and goats), humans and ticks collected simultaneously in a study area of Akonolinga, a health district in the Central Region of Cameroon.From the 15th to the 28th July 2024, a cross-sectional study was conducted in Akonolinga, by collecting survey data, serum samples (from humans, goats and cattle) and picking ticks from cattle and goats. This study included 100 randomly selected households from eight localities.Data were also collected using questionnaires to assess CCHFV seropositivity associated factors. Individual characteristics of 189 goats and 246 cattle were collected and the data georeferenced. To assess the prevalence of CCHF, serological (ELISA) and molecular (real time RT PCR) methods were used to detect antibodies targeting CCHF viral nucleoprotein and CCHFV specific RNA in collected sera, respectively. The presence of CCHFV specific RNA was also assessed in tick homogenate using real time RT PCR.The overall CCHFV seroprevalence was 1.9% [(95% CI (1.02%-3.64%)] in humans, 10.9% [(n=42 ;] in cattle and of 3.38% [(n=5 ; 95% CI (1.45%-7.66%)] in goats. Seroprevalence in cattle increased significantly with age. A total of 554 ticks were collected from 162 of the 386 (42%) cattle examined, with Rhipicephalus (Boophilus) microplus being the dominant species. CCHFV RNA was detected in two sera of women sampled. Phylogenetic analysis of a small portion of the L segment classified the strain within the African genotype III.This study reported for the first-time the proven exposure of the human population to CCHFV in central Cameroon, showing strong evidence that CCHFV is infecting humans. Serological analyses revealed exposure of cattle and goats to CCHFV-strains collected in the same geographical area. These results demonstrate the potential risk of CCHF emergence in the human population, especially in rural areas in close vicinity with animals.