Scrub typhus meningitis: An under-recognized cause of aseptic meningitis in India

Central nervous system (CNS) involvement in scrub typhus is seen in up to a quarter of patients. However, the literature on cerebrospinal fluid (CSF) analysis and outcome in meningitis/meningo-encephalitis due to scrub typhus is scant. This retrospective study included patients who were admitted to a medical college hospital with scrub typhus meningitis/meningo-encephalitis between 2005 and 2011. The clinical and laboratory profile, details of CSF analysis and outcome were documented. The study included 189 patients with meningitis/meningo-encephalitis due to scrub typhus. The mean age of the patients was 41 ± 4 years. The mean duration of fever before presentation was 9.4 ± 3 days. The common presenting complaints were headache (64.2%), nausea/vomiting (60%), altered sensorium (53.7%) and seizures (22.1%). The presence of an eschar was documented in 27.5% of the patients. The mean CSF white blood count was 80 cells/cu mm (range: 5-740). There was a clear lymphocyte predominance (mean 87.6%). The mean CSF protein level was 105 mg% (range: 13-640). The mean CSF sugar level was 63.9 mg% (range 25-350), and was less than 40 mg% in 11.1% of the cases. The case fatality rate was 5.8% (11/189). Univariate analysis showed the presence of an eschar (15.4% vs 2.2%; Odds Ratio [OR]: 8.1) and altered sensorium (9.8% vs 1.1%; OR: 9.2) to be significant predictors of mortality. In endemic regions, scrub typhus should be considered in the differential diagnosis of aseptic meningitis. Modest elevation of cells in the CSF with lymphocytic pleocytosis and multi-organ involvement may indicate scrub typhus meningitis/meningo-encephalitis.