Assays for Crimean-Congo Hemorrhagic Fever Evaluated

The characteristics, performance, and on-site applicability of serologic and molecular assays for diagnosis of Crimean-Congo Hemorrhagic Fever (CCHF) have been evaluated.

The evaluation included evaluated enzyme-linked immunosorbent assays (ELISA), immunofluorescence, quantitative reverse transcription polymerase chain reaction (RT-PCR), and low-density macroarray assays for detection of Crimean-Congo hemorrhagic fever virus.

Scientists from five different institutions under the auspices of the Institut Pasteur (Paris, France) tested a serum panel that consisted of 66 stored serum samples from acute-phase CCHF patients, who had recovered or died; and patients with confirmed CCHF diagnosis who had an early recovery; 32 samples from febrile patients who had symptoms compatible with CCHF viral infection; and 41 samples from healthy persons.

For specific CCHF serodiagnosis, a commercial immunoglobulin (Ig) M and IgG ELISA (Vector-Best; Novosibirsk, Russia) and a commercial IgM and IgG IFA (Euroimmun; Luebeck, Germany) were selected. For detection of the CCHF viral genome, a commercial real-time RT-PCR (Altona-Diagnostics; Hamburg, Germany) and a low-cost, low-density macroarray were used.

A total of 138 and 90 samples from the collected patient serum panels were tested for CCHFV-specific IgM by the Vector-Best ELISA and the Euroimmun IFA, respectively. Because of limited sample amounts, IFA could not be performed on all collected samples. When compared with the reference IgM serology tests, the sensitivity of the IgM ELISA ranged from 75.0% to 100.0% for different laboratories, with an overall sensitivity of 87.8%.

When compared with the reference IgG serology tests, the estimated sensitivity for the IgG ELISA ranged from 75.0% to 100.0%, with an overall sensitivity of 80.4%. For the IgG IFA, sensitivity ranged from 40.0% to 100.0%, with an overall sensitivity of 86.1%, and 79.6% to 83.3% for genome detection. Specificity was excellent for all assays, but molecular test results were influenced by patient country of origin.

The authors concluded that their findings demonstrate that well-characterized, reliable tools are available for CCHF diagnosis and surveillance. The on-site use of such assays by health laboratories would greatly diminish the time, costs, and risks posed by the handling, packaging, and shipping of highly infectious biologic material. The study was published in the December 2012 edition of the journal Emerging Infectious Diseases.

Related Links:
Institut Pasteur
Vector-Best
Euroimmun