Pathogenesis and Pathology of Smallpox
المؤلف:
Stefan Riedel, Jeffery A. Hobden, Steve Miller, Stephen A. Morse, Timothy A. Mietzner, Barbara Detrick, Thomas G. Mitchell, Judy A. Sakanari, Peter Hotez, Rojelio Mejia
المصدر:
Jawetz, Melnick, & Adelberg’s Medical Microbiology
الجزء والصفحة:
28e , p503
2025-11-26
78
Although smallpox has been eradicated, the pathogenesis of the disease (described here in the past tense) is instructive for other poxvirus infections.
The portal of entry of variola virus was the mucous mem branes of the upper respiratory tract. After viral entry, the following are believed to have taken place: (1) primary multiplication in the lymphoid tissue draining the site of entry; (2) transient viremia and infection of reticuloendothelial cells throughout the body; (3) a secondary phase of multiplication in those cells, leading to (4) a secondary, more intense viremia; and (5) the clinical disease.
In the preeruptive phase, the disease was barely infective. By the sixth to ninth day, lesions in the mouth tended to ulcerate and discharge virus. Thus, early in the disease, infectious virus originated in lesions in the mouth and upper respiratory tract. Later, pustules broke down and discharged virus into the environment of the smallpox patient.
Histopathologic examination of the skin showed proliferation and cytoplasmic inclusions of the stratum spinosum. There was infiltration with mononuclear cells, particularly around dermal vessels. Epidermal cells became swollen through distention of cytoplasm and underwent “ballooning degeneration,” with enlargement of cytoplasmic vacuoles. The cell membrane broke down and coalesced with neigh boring, similarly affected cells, resulting in the formation of vesicles. The vesicles enlarged and then became filled with white cells and tissue debris. All of the layers of the skin were involved, with subsequent dermal necrosis. Thus, scarring occurred after variola infection. Similar histopathology is seen with vaccinia, although vaccinia virus ordinarily causes localized pustular lesions only at the site of inoculation.
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