Читать книгу Studies on Epidemic Influenza: Comprising Clinical and Laboratory Investigations - University of Pittsburgh. School of Medicine - Страница 11

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The length of the prodromal stage—the stage from the time of contact to the earliest onset of symptoms—has always led to interesting observations and discussion. In this epidemic we have rather definite information bearing upon this subject.

A young married farmer living in a rural community where no influenza had occurred up to the time of the present experience went to a city about 40 miles distant. On the train he sat in the same seat with a man who was apparently ill, and who was sneezing and coughing. He was in the city only a few hours, and was not in any place of congregation except the railway train. Forty-eight hours after his return to his home he noticed the first symptoms and began a mild course of influenza. About 50 hours later his wife was taken with the same symptoms, and in two days more their only child was afflicted. Other members of the household were also afflicted, and one of them died of pneumonia.

It might be interesting to quote a similar observation made by Macdonald and Lyth, of York, England, published in a recent issue of the British Medical Journal (November 2, 1918, p. 488), which corroborates this experience. They say: “We traveled from London together on Thursday, October 3, by train, leaving King’s Cross at 5.30 P. M., arriving in York at 9.30, and as we were leaving the carriage a young flying officer, who had come the whole way with us and was coughing and sneezing at intervals, informed us that he was ill and had had influenza for several days. On Saturday, October 5, we both became ill and had developed typical attacks of influenza. With both of us the illness developed suddenly with laryngitis; in both the first signs were a severe attack of coughing; and in both the time was noted fairly accurately as being between 2 and 2.30 P. M. One case was quite mild, the temperature never over 101. The other was more severe; the temperature arose to 104½ and the catarrh extended to the bronchi. His wife and two children also developed influenza, and in their case the symptoms showed suddenly, about 2 P. M., on Monday, October 7. Now we are convinced that we became infected from our traveling companion during the train journey—more likely toward the end of the journey; and if we take the time of infection as 9.30, this fixes the incubation period for both of us at a minimum of 41 hours, with a maximum margin of error of 4 hours. The three cases developing in the family of one of us point to a similar incubation period, as their illness started almost exactly 48 hours after his, and as it is likely that the infection would not take place until a few hours after the first symptom, the incubation period in these three cases must have been nearly the same as our own two.

“It can be readily understood that we were in no position to conduct extensive bacteriological examinations, but a culture taken from the posterior nares of one of us on October 10 with a guarded swab showed colonies of Pfeiffer’s bacillus and of micrococcus catarrhalis.”

This observation is so convincing, I have quoted it at length and in full.

The communicability of influenza has been observed by all, and the ease with which it passes from one individual to another noted. One observation made by us was of considerable interest. In a house where a patient lay sick with a severe attack of influenza for nearly three weeks several members of the household passed the door of the sick room a number of times daily, and yet they did not contract the disease. This is in marked contrast with the immediate contact between the two physicians and the young flying officer, who sat in the same railway carriage compartment for four hours. The same observation was made in the hospital among nurses in direct contact with patients. A large number of these contracted the disease, while those not immediately associated with influenza patients almost invariably escaped. This speaks strongly against the idea that the epidemic was a so-called “plague,” or that it passed without intermediate means through the air and pervaded all places.

From information thus far at hand it seems, therefore, that the prodromal stage, or stage of incubation, is one which covers about 48 hours, and that it is usually without symptoms unless it be a peculiar prostration which had been described by some patients. It would also appear from the experiences just narrated that it was necessary to be in rather close contact with a patient, so that there could be an exchange of respired air before infection could take place.