Investigation of Rickettsia conorii in Patients Suspected of Having Crimean-Congo Hemorrhagic Fever.

Rickettsia conorii is the causative agent of Mediterranean spotted fever (MSF). Misdiagnosis of MSF may occur with febrile syndromes associated with rash and thrombocytopenia, such as Crimean-Congo hemorrhagic fever (CCHF). This study aimed to determine the prevalence of R. conorii among serum samples obtained from 260 suspected CCHF patients with features of MSF in Iran (2018-2020). The quantitative polymerase chain reaction (qPCR) method detected three (1.15%) positive 16S rDNA Rickettsia spp. samples that were classified as R. conorii subsp. conorii, R. conorii subsp. Israelensis, and R. helvetica using the sequencing of gltA, ompA, and 17kDa genes. Furthermore, R. conorii IgM antibodies presented in 38 (14.62%) patients by the enzyme-linked immunosorbent assay (ELISA) method. Out of 97 MSF patients with available paired serum samples, IgM seroconversion and a four-fold increase were observed in 14 (14.43%) and 12 (12.37%) patients, respectively. We concluded that rickettsial agents are present in Iran and may be misdiagnosed with other febrile syndromes.