Serological evaluation of Crimean-Congo Hemorrhagic fever in humans with High-Risk professional exposure and in residual sera collected in 2022-2023 across Corsica (France)

Abstract

Background

The Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne pathogen known to cause severe viral hemorrhagic fever.

Aim

We aimed to evaluate the potential circulation of CCHFV in Corsica through a serosurvey, including anonymized residual sera (RS) and high-risk individuals exposed to animals and/or tick bites due to occupational activities.

Methods

This cross-sectional study involved two groups: anonymized RS from medical biology laboratories and sera from high-risk individuals (slaughterhouse workers, veterinary professionals, animal farmers, and rangers) collected across Corsica during 2022–2023. Antibodies targeting the CCHFV viral nucleoprotein were detected using a double-antigen ELISA. ELISA-positive samples underwent neutralizing antibody testing. Sociodemographic and epidemiological data were collected using a structured questionnaire in the high-risk group.

Results

Total anti-CCHFV seropositivity was of 0.08 % (n = 2) [95 % Confidence Interval (CI): 0.06–0.09] in RS and of 0.50 % (n = 1) [95 % CI: 0.43–0.56] in high-risk groups (p < 0.01). Lifetime tick-bites was reported by 65.9 % (n = 118) of respondents, with higher rates among farmers (Odds Ratio (OR) = 3.4; 95 % CI 1.4–8.5) and participants with >10 years of occupational exposure (OR = 3.8; 95 % CI 1.7–8.5).

Conclusions

This study provides initial evidence of human exposure to CCHFV in Corsica, with rates consistent with those observed in other Western European regions. Our results indicate a risk of CCHF among the Corsican population, particularly among farmers and slaughterhouse workers. Continuous surveillance and public education are essential to mitigate this risk, especially among these targeted groups and healthcare professionals, ensuring prompt diagnosis and prevention of potential outbreaks.