Serological Study of Bulgarian Patients With Brucellosis

Abstract

Background: Brucellosis is a widespread zoonotic infection with significant health and socio-economic impacts. This determines the need of a reliable laboratory diagnosis both in endemic areas around the world and in countries where it is rare and under diagnosed. Due to prolongedand hazardous cultivation procedures, the diagnosis is mostly serologically confirmed. Aim: Serological study of Bulgarian citizens with clinical and/or epidemiological data compatible to brucellosis for the period 2005-2015. Materials and methods: Based on clinical and epidemiological data obtained via standard questionnaire 3394 persons suspected for brucellosis along with 106 controls were serologically studied with Rose Bengal slide test, Standard agglutination test, Coombs’ test, Brucellacapt and ELISA. Results: Brucellosis was confirmed in 174 patients. In outbreak related cases the tests listed above were positive in 127 (78.88%), 115 (71.43%), 34 (91.98%), 143 (95.33%) and 104 (96.30%), respectively. A statistically significant positive correlation was found between Coombs’ and Brucellacapt in the studied 55 sera samples (rs = 0,72; p < 0,0000). The profile of anti-Brucella antibodies was investigated in 46 patients with different duration of the disease. In 29 (63.0%) of them the initial serum sample was positive for the three classes of antibodies and in 17 (36.9%) the primary testing didn’t detect IgM, but IgG and IgA. Conclusion: None of the serological tests alone could ensure an accurate diagnosis of brucellosis. It is necessary to use a diagnostic algorithm with appropriately selected serological tests in which Brucellacapt could successfully replace Coombs' test´ for detection of incomplete antibodies in brucellosis with long duration.