Scrub typhus and spotted fever among hospitalised children in South India: Clinical profile and serological epidemiology

Background: Rickettsial infections are re-emerging. In India, they are now being reported from several areas where they were previously unknown. Objectives: The objective of this study was to describe the epidemiology, clinical profile and outcome of serologically-confirmed scrub typhus and spotted fever among children in a tertiary care hospital in Bengaluru. Materials and Methods: Hospitalised children aged rickettsial disease admitted between January 2010 and October 2012 were included prospectively. Diagnosis was based on scrub typhus and spotted fever-specific IgM and IgG by enzyme-linked immunosorbent assay (ELISA). Results: Of 103 children with clinical features suggestive of rickettsial illness, ELISA test confirmed 53 cases for scrub typhus, 23 cases for spotted fever group and 14 with mixed infection. The average age was 7.3 (±3.9) years and 44 (71.0%) children were male. Majority of cases were from Karnataka (50%), Andhra Pradesh (32.3%) and Tamil Nadu (17.7%). Common clinical features included fever (100%, average duration 11 days), nausea and vomiting (44%), rash (36%); eschar was rare. Compared to the ELISA test, Weil-Felix test (OX-K titre of 1:80) had a sensitivity and specificity of 88.7% and 43.9%, respectively. Treatment with chloramphenicol or doxycycline was given to the majority of the children. Complications included meningoencephalitis (28%), shock (10%), retinal vasculitis (10%) and purpura fulminans (7%). Conclusions: These findings suggest that the burden of rickettsial infection among children in India is high, with a substantially high complication rate. Rickettsial-specific ELISA tests can help in early diagnosis and early institution of appropriate treatment that may prevent life-threatening complications.