Central nervous system involvement in patients with scrub typhus

Scrub typhus, which is caused by Orientia tsutsugamushi, is a systemic illness that causes generalized vasculitis. The central nervous system (CNS) is the most crucial target in other rickettsial diseases; however, there have been several reports of encephalitis or meningitis without direct evidence of rickettsial invasion of the CNS in cases of scrub typhus. To investigate CNS involvement in cases of scrub typhus, we analyzed the CSF profiles (cell count and levels of protein and glucose) and amplified rickettsial DNA in CSF specimens by means of nested polymerase chain reaction (PCR) for 25 patients with the infection. Mild pleocytosis was present in 48% of the patients: CSF white blood cell counts ranged from 0 to 110/mm³ (mean [±SD] count, 16.3 ± 27.0/mm³), and the mean (±SD) lymphocyte proportion was 51.9% ± 23.9%. The CSF protein level was increased (>50 mg/dL) in seven patients. Nested PCR amplified six products from the 25 CSF specimens: four of the products were Boryong genotypes, and two were Karp genotypes. The results of this study suggest that O. tsutsugamushi does invade the CSF and that scrub typhus should be considered one of the causes of mononuclear meningitis in areas of endemicity.