Screening for Crimean-Congo Haemorrhagic Fever Virus in humans living in an endemic area of Spain.

Abstract Purpose Crimean-Congo haemorrhagic fever (CCHF) is a tick-borne disease caused by CCHF virus (CCHFV). CCHF is an emerging infectious disease. Recently, the disease has been described in humans in Spain. Most cases have been described in the central-western area of the Iberian Peninsula. This study aimed to evaluate the seroprevalence of anti-CCHFV antibodies in humans in this endemic area of Spain. Methods Study was conducted to estimate the seroprevalence of anti-CCHFV antibodies among patients referred to a hospital located in the central-western area of Spain, an endemic area for CCHFV of Spain. Patients were recruited from April 1, 2023, to June 30, 2023. A commercial ELISA was used to detect anti-CCHFV serum antibodies. Principal findings We screened 658 samples from 370 (56.2%) men, with a mean (±SD) age of 58.6 years (± 14.3). Of these, 4 were IgG positive, representing an IgG seropositivity of 0.6% (95% CI, 0.01-1.19). None of these four patients recalled having a clinical picture that strongly suggested CCHF. The incidence of CCHF in the Bejar area was 33.2 cases per 100,000 inhabitants. Conclusions Our results suggest active circulation of the virus in humans in western Spain. More extensive clinical and epidemiological studies are needed. Although the risk is considered low, clinicians should be alert to the possibility of new CCHF cases, given the high pathogenicity of CCHFV and the risk of transmission. A detailed medical history of each patient is critical for rapid diagnosis, appropriate adoption of therapeutic measures and timely control of the infection.