Sero-evidence of Rickettsia Infection by ELISA in the Northern-Central Area of Bangladesh.

Abstract

Detection of rickettsia most commonly done by simple, economical Weil-Felix test which detects IgM antibody. This initial investigation provides limited sound guidance to clinical decisions because of its low specificity and sensitivity. An alternative test, enzyme-linked immunosorbent assay (ELISA) is faster, less complicated, can also be automated. Advancements in molecular method like polymerase chain reaction (PCR) are highly specific, sensitive and rapid assays for detection of rickettsiales in many different samples including blood, tissue etc. This study was carried out to diagnose the rickettsial agent in the north-central (Mymensingh division) area of Bangladesh. In laboratory, we performed ELISA and PCR. The agent was diagnosed up to species level by molecular approach. A total of 150 febrile patients were included. All were clinically suspected cases of rickettsial fever attending inpatient and outpatient department of medicine and pediatrics of Mymensingh Medical College Hospital from Octy 2012 to January 2014. The laboratory tests were performed in Microbiology department of Mymensingh Medical College. Following universal safety precautions blood samples were collected, serum separated and both were stored at -20°C. IgM ELISA and Nested PCR were performed. Several genes by PCR were detected for confirmation of the presence of rickettsial agent in the blood. Among 150 clinically suspected cases 76(50.66%) were positive for ELISA, and 69(46.0%) were positive for PCR. The sensitivity and specificity of ELISA were 92.75% and 85.19% respectively taking PCR as gold standard. The prevalence of rickettsial infection found in this study was very much close to other countries of this Sub continent.