Transmission electron microscopic study of the hemorrhagic spots in patients with epidemic hemorrhagic fever in the early stage.

Epidemic hemorrhagic fever (EHF) virus particles were found in the squamous epithelial cells and the capillary endothelial cells of the petechial spots located on the mucous membrane of the soft palate in 3 patients with severe early-stage EHF with transmission electron microscopy. The virus particles were round or oval in shape, about 100 nm in diameter, with a two-layer lipid envelope from which spikes were protruding. The nucleocapsid of the virus appeared to be hollow microfilamentoid or dense granules. Meanwhile, budding virus particles with a diameter of 80 nm were found in the enlarged Golgi apparatus. The infected cells displayed an enlarged and proliferating Golgi apparatus. The morphological characteristics of the viron mentioned above coincided with those of the virus particles of the family Bunyaviridae. This study is the first to demonstrate that the squamous epithelial cells on the mucous membrane of the soft palate are the target cells of EHF infection and to provide subcellular morphological evidence of petechial hemorrhage at the soft palate.