Clinical Effects of Smallpox: Pathophysiology of Natural Infection

Infection

Infection begins when the virus comes into contact with the oropharyngeal or respiratory mucosa. The infectious dose is unknown but is believed to be only a few virions. (9:4)Virus multiplication then occurs in the regional lymph nodes. An asymptomatic viremia develops on about the third or fourth day, followed by multiplication of virus in the spleen, bone marrow and lymph nodes. (9:4) A secondary viremia begins on about the eighth day of infection, and is accompanied by the first symptoms of illness – the prodrome, characterized by fever and other symptoms. The virus, contained in leukocytes, then localizes in small blood vessesl of the dermis and beneath the oral and pharyngeal mucosa and subsequently infects adjacent cells. (9:4) In the skin, the virus localizes in small blood vessels of the dermis and in the oral and pharyngeal mucosa. The result is the characteristic rash. (19:5)

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