Hospital based serological evidence of rickettsial diseases and assessment diagnostic tests of pyrexia of unknown origin.

The present study examined hospital-based serological tests of rickettsial infections and assessment for diagnosis of pyrexia of unknown origin (PUO). Blood samples were tested for Weil Felix antigens, ELISA for scrub typhus group and polymerase chain reaction (PCR) to detect the presence of DNA of spotted and scrub typhus group with the help of specific oligonucleotide. We tested 450 patient samples and found 101 Weil Felix-positive with 15 having ≥320 titres. IgM ELISA identified 32 (7.1%) positive cases. Positive PCR was seen in 13 (2.9%) samples, being only 40.1% of those testing positive for ELISA. Rickettsial infection is predominantly diagnosed through serological evidence in combination with molecular techniques. The Weil Felix test has a number of disadvantages and tends to provide false-positive results in a number of scenarios, especially where scrub typhus and spotted fever are widely distributed.