Detection of coxiella burnetii antibodies in patients with suspicion of brucellosis and atypical pneumonia by ELISA and IFA methods

DETECTİON OF COXIELLA BURNETII ANTIBODIES IN PATIENTS WITH SUSPICION OF BRUCELLOSIS AND ATYPICAL PNEUMONIA BY ELISA AND IFA METHODS Q fever, is a zoonotic infection which causes highly variable clinical manifestations, ranging from asymptomatic to acute, fatal chronic infection. The disease is probably underdiagnosed because of the non-specific nature of its clinical signs, the requirement for a laboratory test to establish a diagnosis, and the lack of awareness of this disease in medical and veterinary communities. In this study, the sera of 84 patients who were determined to be negative for Brucella, Mycoplasma and Chlamydia infections in the Serology Laboratory of Dokuz Eylül University Hospital, between January 2013 and August 2013 and whose clinical and laboratory data were compatible with Q fever, were investigated for the presence of C. burnetii antibody with ELISA and IFA methods. Forty six female (54.8%) and 38 male (45.2%) patients were participated in the study group consisting of between the ages of 1-67 (mean age: 30.00 ± 21.764 years). C. burnetii IgM and IgG antibodies were found to be positive in three (3.6%) and nine (10.7%) patients respectively, by both ELISA and IFA methods. False positive results for IgG antibodies were found in two patient (2.4%) by ELISA. The rates of IgM and IgG antibodies in female patients were 2.2% and 8.7% respectively, while these rates were 5.3% and 13.2% in male patients and these discrepancies were not found to be statistically significant (p> 0.05). When the distribution of C. burnetii antibodies between pediatric and adult patients was analyzed, the difference was not statistically significant for IgM (p> 0.05), but IgG antibodies were only detected in adult group with the rate of 16.1% and this discrepancy was statistically significant (p <0.05). IgM and IgG antibodies were mostly detected between the ages of 21-40 (14.3%) and 41-60 (19.2%), respectively. In our study, IgG antibodies which were consistent with previous infection detected in eight patients, while IgM antibodies solely were found to be positive in two patients. Clinical and serological findings were compatible with acute Q fever, for one patient whose phase II IgM was >1:50, phase II IgG was >1:200 and anticardiolipin antibody was positive. As a result, we consider that in order not to miss the diagnosis of Q fever which can lead to different clinical manifestations, Q fever should be investigated not only in the risk groups who are in contact with animals, but also in patients with fever of unknown origin, patients with suspicion of brucellosis, influenza-like illness, atypical pneumonia, hepatitis and endocarditis. Key words: Q fever, ELISA, IFA, brucellosis, atypical pneumonia