Читать книгу Studies on Epidemic Influenza: Comprising Clinical and Laboratory Investigations онлайн

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There was observed one noteworthy thing about seasons. While the great pandemic of 1889 and 1890 had no definite connection with seasons, the epidemic types which followed in 1891 and 1892 seemed to show a lighting up in either spring or fall, remaining dormant in the summer months. It has also been shown by the history of former epidemics that almost all the pandemics started from Russia in the fall, winter and spring months. Such was the case in 10 of the great pandemics of 1729 to 1889. This, no doubt, was the reason so many of the former historical writers were impressed by seasons and meteorological conditions. The statement made by observers during the epidemic that influenza presented two phases, one pandemic and the other endemic, and that each follows different epidemiological rules, seems possible. The question raised during the last epidemic of the spread of the disease in families, the disease occurring at high altitudes and even at sea, we know does not interfere with the recognition of its spread by direct contagion. Definite examples of families or villages being infected by a returned member of such family or citizen from abroad are reported frequently, and even the appearance of the disease in isolated places has often been traced and verified from a definite source, to say nothing of the question of carriers and those supposed to be suffering from other diseases.