[A prognostic model of a cholera epidemic]. / Prognosticheskaia model' épidemii kholery.

A new model for the prognostication of cholera epidemic on the territory of a large city is proposed. This model reflects the characteristic feature of contacting infection by sensitive individuals due to the preservation of Vibrio cholerae in their water habitat. The mathematical model of the epidemic quantitatively reflects the processes of the spread of infection by kinetic equations describing the interaction of the streams of infected persons, the causative agents and susceptible persons. The functions and parameters of the model are linked with the distribution of individuals according to the duration of the incubation period and infectious process, as well as the period of asymptomatic carrier state. The computer realization of the model by means of IBM PC/AT made it possible to study the cholera epidemic which took place in Mexico in 1833. The verified model of the cholera epidemic was used for the prognostication of the possible spread of this infection in Guadalajara, taking into account changes in the epidemiological situation and the size of the population, as well as improvements in sanitary and hygienic conditions, in the city.

[A mathematical model of the seasonal morbidity of shigellosis]. / Matematicheskaia model' sezonnoi zabolevaemosti shigellezami.

A new epidemiologically significant mathematical model for the prognosis of seasonal morbidity in dysentery caused by S. flexneri and S. sonnei has been developed. This model may be used for solving problems on the epidemiology of Shigella infections. In this model quantitative ratios are determined by means of the system of nonlinear integral-differential equations in partial derivatives of the first order with edge conditions of the integral type. This model makes it possible to make multiple calculations with a view to obtaining the most probable picture of the development of the epidemic process at individual territories, to ascertain and make prognosis the terms and peaks of morbidity rises year after year in succession. The model permits the evaluation of specific features of the course of dysentery in patients of different ages in different groups of the population, affected by various nosological forms of shigellae. The relationships indicated by the model have been realized in the form of the computer program "SHIGELLA C" permitting multiple calculations of dysentery morbidity by means of an IBM PC/AT.

Aspectos epidemiologicos de la lactancia materna en una poblacion derechohabiente del IMSS en Mexico. / Epidemiologic aspects of breast feeding in an insured population of the Mexican Social Security Institute (IMSS)

Entre los objetivos del presente estudio, se pueden senalar dos, como los mas importantes: explorar en forma retrospectiva los cambios en el patron de alimentacion infantil, en los ultimos 20 anos en Mexico, e investigar algunos factores socieconomicos y culturales, que afectarian la ocurrencia y duracion de la lactancia natural