(27) Further to this they write that: Downie and Dumbell (1947) recovered variola major virus from crusts stored at room temperature, in the dark or in daylight, for up to 1 year; Wolff and Croon (1968) recorded the persistence of viable alastrim
(variola minor) virus in scabs kept in envelopes in a laboratory cupboard for over 13 years.
In the twentieth century virulent smallpox (variola) was replaced naturally in Britain by a milder type (alastrim
), antigenically identical but with a much lower mortality (1 percent).
Thus smallpox was still well defined within ICD-9-CM (1996): 050 Smallpox Excludes: arthropod-borne viral diseases (060.0-066.9) Boston exanthem (048) 50.1 Variola major hemorrhagic (pustular) smallpox Malignant smallpox Purpura variolosa 50.1 Alastrim
Variola minor 50.2 Modified smallpox Varioloid 050.9 Smallpox, unspecified (ICD-9-CM, 1996, vol.
Em 1930, o numero de casos de variola decresceu substancialmente, e na decada seguinte predominou a variola minor ou alastrim
. A mortalidade na capital federal, de 53% entre 1925 e 1930, caiu para 4,1%, entre 1931 e 1935.