Comparative study between serological tests and PCR for diagnosis of Rickettsial diseases in patients with fever of unknown origin

Abstract

Background and aimRecurrence of Spotted fever and Scrub typhus fever has been well documented in pyrexia of unknown origin (PUO) cases from Iraq in past years. Therefore the present study were carried out in the rural area of Iraq where there is a steady interface of human being with animal reservoir, to detect the occurrence of Rickettsial infections as well as to compare the conventional serological and molecular methods for its diagnosis. MethodsA total of 91 blood samples collected from PUO were tested for Widal (Typhoid), Weil Felix (Typhus), Standard agglutination (Brucellosis), IgM Scrub ELISA and IgM Spotted ELISA and dMicrolisa-HIV. The positive ELISA samples were subjected to PCR to detect Rickettsiae by using specific primer for 16S rRNA gene sequence. ResultsOut of 91 patients, 19 (20.8%) were positive for typhoid fever. IgM Scrub and Spotted ELISA shows positive for 26 (28.5%) patients. Among 26 ELISA positive, 14 were negative for Weil Felix test. Out of 20 Weil Felix positive samples, only 12 were positive in ELISA. The PCR results were positive for 8 (30.8%) samples out of 26 ELISA positive samples. ConclusionScrub typhus and Spotted fever were widely distributed in PUO cases. Measures to increase awareness and also to diagnose and treat this infection in the affected areas are essential.