Only one adult TBE patient had TBEV RNA detected in plasma and full blood during the neurologic phase of the disease—a woman 68 years old, immunocompetent, anti-TBEV IgM and IgG positive in serum and CSF, with a biphasic disease lasting 19 days since the onset and 8 days since the beginning of the neurologic phase. This evidence concerns the gene CD40LG and tick-borne encephalitis.