Smallpox in Toronto, 1962.

A 14-year-old boy was seen on August 17, 1962, with a vesicular eruption of five days' duration. The vesicles were about 0.5 cm. in diameter, loculated, mainly distributed centrifugally, and all were at the same stage of development. On August 8, he left his residence in a rural area of southern Brazil where alastrim is endemic. His last smallpox vaccination was received at least six years ago. Alastrim virus was isolated from vesicle fluid obtained on August 17 and 19 by inoculation of chorioallantoic membranes of embryonated eggs. A fourfold rising level of vaccinia antihemagglutinin in paired serum samples was consistent with infection by alastrim virus. The patient has since recovered uneventfully.