Eschar and IgM ELISA in the diagnosis of scrub typhus

Scrub typhus is one of the leading causes of acute febrile illness in India. This study aimed to determine the best diagnostic tool for the identification of scrub typhus and study the possible association between diagnostics and clinical characteristics. Patients with fever of ≤15 days admitted to the hospital satisfying the case definition of 47 kDa quantitative polymerase chain reaction (qPCR) positivity OR scrub typhus IgM ELISA positivity along with the presence of eschar OR Scrub typhus IgM ELISA positivity along with defervescence of fever within 72 h of initiation of specific therapy were recruited. Of the 116 patients satisfying the case definition, 47 kDa qPCR was positive in 43 (37%) patients, whereas IgM ELISA was positive in 104 (90%) patients and eschar was seen in 59 (51%) patients. The median duration of fever was 7.5 days (interquartile range 6-10 days). Multiorgan dysfunction syndrome (MODS) was described in 44 (37.9%) patients. Two patients (1.8%) succumbed to the illness. Presence of eschar and IgM ELISA positivity were detected in 106 (91%) cases. Scrub typhus, even with MODS, has low mortality because of immediate institution of specific therapy due to physician awareness. The presence of eschar and IgM ELISA positivity can be used to detect a majority of cases of scrub typhus.