abstract

Scrub typhus is an emerging zoonotic infection caused by a small obligate intracellular bacterium, Orientia tsutsugamushi, which is transmitted by the bite of infected trombiculid mites. Problems with diagnosis because of the nondescript clinical characteristics of the disease and similarities with other tropical infections are considerable. This paper discusses the origin, pathogenesis, immunopathogenesis, and diagnosis of scrub typhus with emphasis on the sensitivity and specificity of serological and molecular diagnostic techniques. Various methods have been used to review the principles, effectiveness, and limitations of the immunofluorescent assay (IFA), enzyme-linked immunosorbent assay (ELISA), conventional polymerase chain reaction, and real-time PCR. It turned out that molecular techniques are the most effective in detecting O. tsutsugamushi DNA in the acute phase of infection while serological techniques have more significant advantages later when immunization occurs. The accuracy of diagnosis is influenced by various factors like the time of sample collection, concentration of the pathogen in the body, the presence of antibodies, cross-reaction, and variations among strains depending on the geographical location. The paper has shown that diagnostic sensitivity and specificity vary according to the method of diagnosis chosen and the stage of the disease the patient is in.