Suspected Crimean-Congo Haemorrhagic Fever Re-Infection: A Case Report with Atypical Serological Profile

A 53-year-old male farmer presented with clinical manifestations consistent with Crimean-Congo Hemorrhagic Fever (CCHF) virus infection, reporting a recent history of tick bite. To confirm the diagnosis, molecular and serological assays were performed on four specimens collected following the onset of illness. Reverse transcription-polymerase chain reaction (RT-PCR) detected CCHF virus RNA in the initial sample, while serum immunoglobulin M (IgM) antibodies were undetectable in all specimens. Notably, a robust immunoglobulin G (IgG) antibody response was observed across all samples. The concurrence of detectable viral RNA with the presence of IgG antibodies, but the absence of IgM, in the acute phase sample suggests a potential case of CCHF virus re-infection. These findings hold significant implications for public health, particularly regarding our understanding of CCHF virus infection dynamics, diagnostics, and vaccine development strategies.