Temporal-spatial-social parameters in the spread of contagious disease.

A conceptual theoretical model was built on the basis of prominent concepts of the generally accepted knowledge on the spread of contagious disease. Subsequently, the model was applied to a real epidemic of variola minor (the mild form of smallpox) and four phases of the epidemic were disclosed. The phases discriminated themselves through their relationships to invasion of certain city subdivisions and rural districts and particularly, through the type of social units involved and the type of persons introducing the disease into these units.

Concepts of diffusion theory and a graphic approach to the description of the epidemic flow of contagious disease.

Concepts used to analyze sociological, geographic, and economic processes were adapted to an examination of the diffusion of contagious disease. The example used in applying these concepts was an epidemic of variola minor which continued for 12 months in an area of 1,006 square kilometers centered on the city of Bragança Paulista, Sao Paulo State (Brazil). A graphic procedure is proposed that depicts aspects of the epidemic flow of person-to-person transmission.

Contour mapping of the temporal-spatial progression of a contagious disease.

A methodology for contour-map study of contagious-disease epidemics is presented. Its application is exemplified in a smallpox epidemic occurring in a small Brazilian town. Computer-controlled contour-mapping of dates of introduction of variola minor into 169 households and the coordinates of the affected dwellings did not show a single contour pattern, but a group of subareal patterns of within-household outbreaks.

Variola minor in Bragança Paulista county, 1956. Observations on the clinical course of variola minor and on pregnancy in women with the disease.

Occasional observations on the clinical course of 485 cases of variola minor composing an epidemic are reported. 17% of the cases showed a complication. Otitis was observed in one case.

Variola minor in Bragança Paulista County, 1956. Distribution of onset of cases in the two schools including most school children with variola.

Class attendance during illness was confirmed for numerous pupils of two schools. Successive generations whose median cases were separated by an interval consistent with the "serial interval" of variola minor were clearly found in the epidemic curve for II of the 29 classes with cases from both schools. Twenty two other classes had no case at all.

Variola minor in Braganca Paulista County, 1956. Flow of the epidemic through the schools of the county.

The characteristics of the 10 elementary, teachers, business and high schools operated in the city capital of the Braganca Paulista County, state of São Paulo, Brazil, during the 1956 epidemic of variola minor (alastrim) are presented. Also shown are the numbers of students with variola and of students without variola but with homemates with variola, by grade and school. Of the total 131 cases recorded among students, 128 occurred in the 4 elementary schools.