The Outcome of PCR Versus IGM Timing Study in the Diagnosis of the Crimean-Congo Hemorrhagic Fever Outbreak in Iraq during 2021-2022

OBJECTIVE: Crimean-Congo Hemorrhagic Fever (CCHF) is a zoonotic viral infection with high morbidity and mortality rates. Iraq experienced a severe CCHF epidemic outbreak in 2021- 2022. Accurate diagnosis requires precise timing for the CCHF polymerase chain reaction (PCR) test and the CCHF immunoglobulin M (IgM) serological test. METHODS: This was a descriptive study of a large case series. Over two years, 380 cases were managed in infectious disease hospitals. Specific investigational data were analysed for CCHF cases positive by anti-CCHF PCR and/or IgM. These data were collected from the Central Public Health Laboratory (CPHL) in Baghdad, the only laboratory accredited for CCHF testing in Iraq. The study was conducted from March 1, 2021, to December 31, 2022. Blood samples were collected and transported according to safety protocols by a private vehicle with accredited personnel to the CPHL. RESULTS: All CCHF cases were diagnosed by PCR or serum CCHF IgM antibodies from all Iraqi governorates. A total of 380 cases of different ages and genders were identified. Diagnosis using PCR was possible from day 1 to day 15 of illness, whereas positive CCHF IgM antibodies indicated diagnosis from day 5 of illness onwards. DISCUSSION: The study explains the optimal timing for CCHF PCR and CCHF IgM testing, showing that early diagnosis improves treatment outcomes and prognosis. CONCLUSION: The gold standard for CCHF diagnosis is PCR testing within the first 15 days of illness, while anti-CCHF IgM testing becomes useful from day 5 onwards.