CD40LG and congestive heart failure: While both the BLACKBOX CCHFV IgM ELISA (Fig 5A, Table 8) and the VectoCrimean-CHF-IgM ELISA (Fig 5C, Table 8) detected 100% of samples that were collected later than day 4 after onset of symptoms as positive (95% CI: 85.2%–100.0%), the BLACKBOX CCHFV IgG ELISA was significantly more sensitive than the VectoCrimean-CHF-IgG ELISA in detecting IgG antibodies in samples collected between day 11 and 19 after onset of symptoms (Fig 5B, Fig 5D, Table 9; BLACKBOX CCHFV IgG: 100% (95% CI: 71.5%–100.0%; VectoCrimean-CHF-IgG: 27% (95% CI: 6.0%–61.0%)).