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

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The old controversy of whether influenza is distributed in a radiating manner or in so-called leaps and bounds is believed to be settled by consensus of opinion that it occurs in both ways. An opinion expressed by the study at this time as to whether influenza spreads more rapidly than any other infectious disease is found in the statement that the contagion is markedly virulent, the micro-organisms are easily conveyed from their original seat in the mucous membrane by coughing, sneezing and expectoration, the great number of persons who, though slightly affected, carried on their ordinary way of life without hindrance, the probable longevity of the organisms in convalescents, the brief period of incubation of two or three days, the susceptibility of all people of every age and vocation, and the possibility of carrying the contagion by merchandise and even through short distances in the air, are all suggestive reasons for this. No one at present accepts the so-called miasmatic nature of the contagion. Proofs are ample to show that one case must be present in a locality or even family, although it may be frequently overlooked, from which the epidemic spreads. During this period of 1889 and 1890 the duration of the actual epidemic period in different localities in Europe was from four to six weeks. This was subsequently shown to be consistent with the recorded reports from the various cities in the United States. Following this pandemic in the first part of the year in 1891 there were numerous epidemic outbreaks in various parts of America, including New Orleans, Chicago, Boston, and simultaneously in England. Strange to say, at this time neither Germany nor France had such epidemics, although both were exposed by travelers, particularly from England and America. The question was raised at that time whether the Germans, French or other continental nations were more immune than Americans and English. In the fall of 1891 and the entire winter of 1892 the disease was extensively prevalent both in Europe and Northern America. In these later epidemics there was no definite direction of spread. They probably would come more clearly under the so-called radiation from numerous rural districts. In almost every case at the point of its origin in these countries the epidemic developed and spread slowly, lasting months and with very varying morbidity and mortality. They had none of the explosive characteristics of the pandemic. The general diminished morbidity of the later epidemic, the diminished geographic distribution of the disease and the scarcely recognizable character of its contagion, its slow development and extension over several months, the continuous diminution in frequency and in intensity since its onset in 1889, have been explained by presumptive successive lessening of susceptibility of the population, possibly due to acquired immunization. Observers at that time, as well as ourselves, could question this last statement.