ELECTRON-MICROSCOPIC EXAMINATION OF RICKETTSIA TSUTSUGAMUSHI-INFECTEDHUMAN LIVER

A 33 year-old Thai woman was diagnosed with scrub typhus infection acc ording to clinical symptoms, eschar lesions compatible with the diseas e, and specific antibody to Rickettsia tsutsugamushi detected by indir ect immunoperoxidase. Percutaneous transhepatic needle biopsies were t aken before and 7 days after treatment with tetracycline to study the pathology of the liver. The liver tissue was evaluated by light micros copy, using H & E and Pinkerton's stains, and by transmission electron microscopy (TEM). Before treatment it showed reactive hepatitis. Rick ettsia organisms within the hepatocytes and sinusoids detected by Pink erton's stain appeared as tiny bright-red organisms. By TEM, the rod-s haped double-membrane Rickettsiae appeared intact in the cytoplasm of Kupffer's cells and hepatocytes. After tetracycline treatment, moderat e levels of acidophilic and ballooning liver cells were observed. The degree of cytoplasmic organelle damage varied, including fatty metamor phosis, depletion of glycogen granules, loss of the mitochondrial cris tae, dilatation of endoplasmic reticulum and cytoplasmic vacuolation. Rickettsia organisms cannot be visualized by Pinkerton's stain but wer e detected by TEM, in markedly vacuolated hepatocytes, in congested si nusoids and in Kupffer's cells. Intranuclear Rickettsia were discovere d ill the endothelial nucleus, showing various degrees of injury. Some were mildly degenerated, while others exhibited clumping of nucleopro tein at the cytoplasm periphery and large vacuolation centrally. Many indented organisms were found, and binary fission during Rickettsiae m ultiplication was always affected. Electron-microscopic examination of hepatic injury associated with scrub typhus is rare. This is the firs t ultrastructural localization of Rickettsiae in the infected human li ver.