Chapter II: Part 2

In the city of Pittsburgh the disease was not made reportable until October 5. However, one case was reported on October 1, and it was known that there were a few isolated cases in Pittsburgh previous to that date. During the months of October, November and up to December 21 there were 23,268 cases of influenza reported, and the deaths were 1,374 from lobar pneumonia and 678 from broncho-pneumonia. We cannot but feel that most of the deaths reported during the period of the epidemic as lobar pneumonia were broncho-pneumonia associated with influenza. It was well known among civilians that true lobar pneumonia was exceedingly rare and has remained so up to the present time. This is especially noticeable, as this is the time of the year when lobar pneumonia is usually widespread in Western Pennsylvania. This district was particularly favored with a mild fall and winter. On October 1 the first case was reported, on October 15 the epidemic reached its peak—on that day 957 persons being reported ill with the disease. From October 16 until October 28 it maintained an average of 600 cases daily; from October 29 until October 31 there was a sharp decline from 600 cases daily down to 200 cases daily. From November 1 until December 21 the decline has been uniform, and on this latter date 58 cases of influenza and 7 of pneumonia were reported. The height of the epidemic was reached between October 15 and October 29. During the period of the epidemic in Pittsburgh, from October 1 until December 15, 62 days were recorded as cloudy, or partially cloudy, and only 14 days as clear, although the cloudy days seemed distributed and not in decided groups. The mean temperature for October was 58 degrees, with normal 54.9; for November, 44 degrees, normal 42.9; for December, 41 degrees, normal 34.7. The precipitation in October was 3.08, as against a normal of 2.36; in November, 1.79, with normal 2.55; and in December, 3.50, normal 2.73. From a study of these weather reports we see that the epidemic occurred during a period of abnormally warm, cloudy and slightly more moist autumnal season than usual, but these variations were relatively slight and far from decided. The confusion of diagnosis between lobar pneumonia and broncho-pneumonia, associated with or following influenza, occurred in the Pittsburgh health reports as well as in other cities. The presumption that almost all, if not all, of the cases reported as pneumonia of different types were really cases of influenzal pneumonia, seems justified.

_Epidemic Incidents in Institutions and Towns of Western Pennsylvania_

During the time the epidemic was at its height in Pittsburgh the Western Pennsylvania Institution for the Blind was in session. This school is located in the heart of the educational center and was surrounded by the barracks of the Student Army Training Corps of the University of Pittsburgh and the Carnegie Institute of Technology. When the influenza was recognized as epidemic in this neighborhood, the attending physician at this institution advised a quarantine against the public. The children were refused visitors in the buildings, and the usual week-end trips home were forbidden. This school was continuously in session from September 24 until November 30. During this time there was not a single case of influenza in the school and the children were free from any infectious disease. On December 1 the pupils returned to school after the Thanksgiving holiday, and one week later, on December 8, the first case of influenza appeared. In a period of five days following 15 cases developed. It was considered wise to close the school, and all well children were sent to their homes. The institution was kept closed until January 1, since which time no cases have developed. Very few of these children had influenza at home, and only one death occurred.

A reliable report, subsequently confirmed by the health officer, stated that in Masontown, Pa., the start and course of the epidemic were very striking. A dance was held in the town and the musicians were brought from nearby cities. One of the musicians employed was not very well upon his arrival, and became so ill that after the dance he was put to bed in the hotel. He was found to be suffering from influenza when examined the following day, and from him as the primary case the town was swept by the epidemic.

In Mercer, Pa., the physician to the Board of Health reported that during September they had a general epidemic of coryza and sneezing, with slight fever, which lasted for three or four days. This was looked upon by the people as hay fever. In the midst of this, or about September 16, a man, 74 years of age, who had been away from home, developed true influenza, followed by pneumonia, from which he recovered about October 10. Another man, employed in Greenville, a nearby town, where influenza was already prevalent, returned to his family here suffering from the disease. The whole family and all who were exposed to this family were infected. From this family as a focus the disease spread rapidly in every direction. There were about 350 cases in the town of 2,000 inhabitants, and there were 9 deaths. Sporadic cases have occurred since, ranging in number from one to a dozen at a time. These numbers do not include scores of cases called colds by the people, but it seems that all these cases had an influenza element.

In the town of New Castle it was not possible to trace the onset of the influenza epidemic to a definite case. As the health officer stated, several cases were reported at once.

The first case of influenza in Indiana, Pa., of which there was any definite knowledge occurred on September 15. A clothing merchant who had just arrived from New York, where he had been buying stock for his store, was the first case identified. The next case occurred several weeks later, the disease being contracted at the mining town of Coal Run, in Indiana County.

A man resident in Sharpsburg who had suffered from influenza visited friends in Fraser Township, Allegheny County, to convalesce. Previous to his coming that section had been free from the disease. He was still coughing at the time, and, moreover, he is said to have been a great talker and visited largely among the neighbors of his host. Threshings in that part of the township were going on and these he also attended. The date of his coming was October 13. By October 15 his hostess was taken ill. By October 16 some of the threshers were affected, and by October 17 enough were sick to break up the work of threshing. Eventually all the men engaged became ill, and 11 families were infected from this source.

_Summary_

Reviewing the history of former epidemics and pandemics, I have gained the impression, as have many others, that we are not dealing with any new disease. Further, our knowledge of this pandemic with its high incidence of broncho-pneumonia shows that it is in no way markedly different from that of former manifestations of influenza. One is impressed by the fact that in different outbreaks of this disease of complex symptomatology certain symptoms or complications have been prominent, overshadowing others, and making such complications the striking feature at the time. The failure to recognize that these varying features are merely different manifestations of one disease has resulted in much confusion. The observation made in the last epidemic—and one which can be endorsed during the present plague—is that influenza has been and is the most widespread, rapid and extensive of all diseases. One thing also that attracts attention at the present time is the long period existing between the several pandemics. Whether, as one observer during the present pandemic has stated, it requires a long period for the infection to become active and easily carried, or whether any possible reason can be suggested for these phenomena, admits of no satisfactory explanation. The outstanding feature during this epidemic is the complication of broncho-pneumonia, and yet, from very early times, this complication has been repeatedly spoken of as a striking characteristic. Reviewing the health reports from the large cities of deaths from pneumonia, the presumptive opinion seems justified that almost all, if not all, pneumonias reported as associated with influenza were of the broncho-pneumonia type. The infrequent presence, indeed the rare finding, of lobar pneumonia during this period in Pittsburgh seems to verify the aforesaid opinion. The great frequency and the high mortality of broncho-pneumonia were particularly noted during the present epidemic. During the present epidemic the great mortality among pregnant women was another striking feature, and yet this is by no means new, having been recorded by some of the earliest writers. Such also may be said of the recurrence of the disease in the same patient. One important observation brought out in the study of the pandemic of 1889 to 1892 was that the ordinary infections occurring in the spring and fall known as grippe or La Grippe are in no way connected with the pandemics which have occurred. There seems to be a consensus of opinions among the records of the more recent epidemics, as well as during the present pandemic, that weather conditions in no way influence the spread of the disease. Furthermore, a study of weather conditions throughout the United States, and particularly those of our own city, seem to bear out the truth of this observation. While clinicians during other epidemics expressed their belief in the incident of a primary case producing infection, it has only been during the present one that such an opinion has not been assailed. The large number of military training camps and cantonments have undoubtedly offered splendid opportunity for the spread of influenza. The futility of attempting to control it even under normal conditions is still questionable. Consistent with former reported invasions of the disease, the present epidemic lasted a definite period. This period was about six weeks in most of our large cities, colleges and institutions, extending approximately from October 1 to November 15.

It is imperative to note the accurate clinical observations recorded from the numerous epidemics of the past by men with far less data to go upon than is available at the present day. The high morbidity among the personnel of many of our hospitals and institutions where the infection occurred and the relatively low mortality deserve attention. This may be partly explained by the methods of treatment of those infected, but not entirely. The great likelihood of carriers of influenza, who either are not ill or who are suffering from very mild infection, is an observation also noted by former writers which cannot be ignored. The value of the masks has not been established, although they have been extensively used in many parts of the country. Frequent throat lavage was generally accepted as a rational preventive measure. Relightings of the disease have been noted in most of our cities after the subsidence of the epidemic. Vaccination against influenza is fully discussed in Dr. Haythorn’s paper in this series.

The presence of influenza in San Quentin prison, California, in April, 1918 (Public Health Reports, May 9, 1919); an epidemic of respiratory disease in Chicago in the spring of 1918; the report of Soper of influenza in our army camps in March and April, 1918; the occurrence of influenza in Porto Rico in June; influenza on a United States Army transport from San Francisco, as reported by Coutant, seem to point to the possibility that influenza had a footing in America long before the disease became pandemic. The view held by some that the beginning of influenza was in America, subsequently being transferred to Europe and then reimported here, is worthy of consideration. Coutant believed the disease originated in Manila, others that it traveled from “a permanent endemic focus in Turkestan,” and there are many other theories which attempt to discover the original source of the disease. The question is today an unsettled one. The pandemic of influenza in its severest form swept so suddenly over the world that before the profession realized it or had become stabilized it had changed its character and the great plague was gone. The consequence has been that we have really learned little that is new and have done scarcely more than establish on a firm basis many of the opinions formed after the great outbreak of some 30 years ago. Because transportation is today more rapid than it was at that time, so the spread of the disease has been correspondingly swift. Our modern life, the congregating crowds in theatres, moving-picture houses and in lecture halls, as well as of the men in our training camps, the development of street cars and the more frequent traveling by train—these and many more changes in our mode of living have served to aggravate the conditions favoring the widespread distribution of the infecting agent. A higher proportion of the population was, therefore, attacked than in any previous pandemic, and the period during which the disease was widely prevalent has for the same reason been relatively much shorter.

The characters differed somewhat in different regions, but the evidence shows clearly that we are not dealing with any new disease. It will be years before we are able to fully analyze the data that have been collected from such wide sources and by so large a body of trained men, so that important epidemiological facts may still be forthcoming from the material already at hand. We are too close to the events to get the most helpful perspective, and the object of this report has been to add, in however small a degree, to the general knowledge of this great pandemic as it has appeared to us in Pittsburgh and its surroundings.

A CLINICAL DESCRIPTION OF INFLUENZA AS IT APPEARED IN THE EPIDEMIC OF
1918–1919

By J. A. LICHTY, M. D.

The epidemics of influenza which have been recorded from time to time during the past few centuries have always contributed an interesting chapter to the history of medicine. The protean character of the disease with its many complications is always an excuse for another attempt at the description of the clinical manifestations of a recent epidemic. This is not, however, the only incentive at the present time for describing the clinical aspect of the disease as it appeared in the epidemic through which we have just passed. The study of the disease from other aspects, such as the pathological, the bacteriological and the physiological, by well-organized groups of workers has made it necessary to co-ordinate, if possible, the clinical findings in every detail with these apparently basic principles. It would be interesting to review here the peculiarly fortunate circumstances which have led to the investigations. On account of the great war many temporary laboratory organizations which otherwise would not have existed were in operation, and these organizations, moreover, were keen to undertake any laboratory problem which might arise. The present epidemic presented the opportunity, and that the work was taken up with great enthusiasm is evidenced by the reports coming from the various army hospitals, base hospitals and civilian hospitals throughout the world. The permanent laboratories connected with medical schools and with institutions for medical research took up the problems with equal endeavor. This brief reference is made only to call attention to the fact that from such organizations a great mass of information has come which must be critically reviewed and coordinated before it can add to the permanent fund of our knowledge of the disease under consideration.

The material upon which the following clinical observations have been made is peculiarly adapted to review because it consists of two distinct groups of patients which were admitted to the Mercy Hospital. One group of 153 men was composed of soldiers between the ages of 18 and 23, which had been recently inducted into the Student Army Training Corps, and were living in barracks in the immediate vicinity of the hospital. Another group consisted of civilians (394), ranging from youth to old age, which came from various parts of the city and surrounding towns and country. The first group came to the hospital early, or as soon as the disease was recognized; the second group came usually after several days of illness had elapsed, or when a complication had already arisen. Many of this group had been ambulatory cases for the first part of the disease. The entire number of patients admitted to the Mercy Hospital from the first admission, September 21 to December 1, the end of the quarantine, was 547. After December 1 very few simple influenza cases were admitted. These 547 cases form the basis of the observations which will be referred to in this paper.

From the last great epidemic or pandemic of influenza, that of 1889 and 1890, have come clinical descriptions which should be reviewed before speaking of the clinical manifestations which have characterized the present epidemic as shown in the two groups studied.

One of the best descriptions of that epidemic was given by Dr. O. Leichtenstern in Nothnagel’s Encyclopedia of Practical Medicine. This contribution, among many others, describing the epidemic of 1889 and 1890 is one of the first to refer to the Pfeiffer bacillus as being etiologically associated with the disease. It differs, therefore, greatly from descriptions of previous epidemics. Leichtenstern says: “The typical influenza consists of a sudden pyrexia of from one to several days duration, commencing with a rigor, and accompanied by severe headache, generally frontal, with the pains in the back and limbs, by prostration quite out of proportion to other symptoms and marked loss of appetite.” He continues by saying that to these characteristic symptoms may be added the catarrhal phenomena arising from the affection of the respiratory tract, particularly the upper (coryza) and “occasionally” the lower, the trachea and bronchi. This description is so in accord with the symptoms of uncomplicated influenza as found in the present epidemic that very little need be added. Any difference which may occur in the description of the disease is likely to be accounted for by the peculiarity of onset, whether in the upper or lower respiratory tract, and by the different ways of interpreting complications which may have arisen. It is evident from this description that the upper respiratory tract was affected more generally than the lower in the epidemic of 1889 and 1890. In the present epidemic it can safely be said that the reverse was the usual state of affairs. It was a rather unusual occurrence when the affection was limited only to the nose, pharynx, larynx, trachea and larger bronchi. A very large number, no doubt, had a peculiar œdema, a so-called “wet lung,” which we shall discuss later; others went on to a capillary bronchitis or a bronchiolitis, and a large number had broncho-pneumonia. This sequence we shall attempt to show in the statistics at hand. In some cases the lesion in the lower respiratory tract seemed to be primary, there having been no initial coryza. At least none was observed and no history was obtained.

_Prodromal Stage and Communicability_

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.

_Duration of the Disease_

In all descriptions of the disease the duration is spoken of as “several days, more or less,” “a three-day fever,” or “a seven-day fever.” Because of the careful supervision under which the soldiers were kept while in the barracks an excellent opportunity was afforded to note the duration of uncomplicated cases. The shortest time observed was 1 day, and the longest 10 days. The average duration of temperature among 87 soldiers without inflammation of the lungs or other certain complications was 6⅓ days. Among the civilians the shortest time of pyrexia was a few hours only, while the longest in 73 male patients was 14 days, and in 84 female patients was 16 days. The average length of pyrexia in the males was 4⅝ days, and in the females was 5¼ days.

While the very definite clinical description of the former epidemics of a so-called uncomplicated influenza seems to have served satisfactorily to the present time, the laboratory studies and the possibly more thorough clinical observations which have been carried out recently in this epidemic make it necessary to present anew the whole disease picture of influenza, with the hope of suggesting a classification more in accord with our present knowledge of the disease.

_Forms and Varieties of Influenza_

A few words as to “forms” or varieties of influenza might be helpful before suggesting a classification of symptoms. In former epidemics of influenza considerable importance was attached to the early manifestations or first symptoms as characterizing the “form” of influenza which was in evidence in the individual patient. These were reported as a “respiratory form,” a “nervous form,” a “gastro-intestinal form,” and other forms—circulatory, renal, psychic, etc. In the epidemic of 1889 and 1890 particularly these types were noted, and they have been described in the subsequent small epidemics, practically characterizing them as being of one or the other, and frequently as being without any respiratory symptoms. In the study of our group of cases in the present epidemic every effort was made to recognize the non-respiratory cases, but we were unable to find a single case which did not have definite respiratory symptoms, either early or late, in addition to any other symptoms present. Only occasionally were nausea, vomiting and diarrhea or tachycardia, or certain neuroses or psychoses, the leading symptoms. The respiratory symptoms in some cases seemed to be at the onset primarily of the lower respiratory system—that is, without the preliminary coryza. These usually ran a rapidly fatal course, characterized by marked cyanosis and confusingly irregular chest signs. We would say, therefore, in so far as our experience goes in this epidemic, we are not justified in speaking of any particular forms except the respiratory form, and whenever pronounced manifestations occurred justifying a characterization of any other form they could more easily be interpreted as a complication, or the manifestation of a coincident disease, or of a severe toxæmia.

The classification of the symptoms, therefore, takes into consideration largely those symptoms arising from the respiratory system. We are of the impression that the pathology demonstrated by Dr. Klotz and described by others justifies the following classification. Clinically we would recognize two distinct groups of epidemic cases.

The first includes those _without lung involvement_ having symptoms arising from the upper respiratory tract, including the trachea and the larger bronchi. These were practically without any chest signs except for the rather indefinite signs of an acute bronchitis, and the only symptoms referable to the respiratory tract were a coryza, soreness of the throat, hoarseness and a cough of varying degree and character. If to these symptoms are added those of Leichtenstern just mentioned, one will have a good description of a so-called simple, uncomplicated influenza.

The second includes those _with lung involvement_ and associated with physical chest signs, in some indefinite and confusing, while in others definitely conforming with the existing pathology. These symptoms and chest signs were those associated at one time with what appeared to be an acute œdema of the lungs. At another time the physical signs were those of a bronchiolitis (capillary bronchitis), or most frequently of a broncho-pneumonia, of an isolated type or of a massive type. Finally there were some forms of lobar pneumonia which at times we were unable to differentiate from a true lobar (croupous) pneumococcic pneumonia.

_Influenza Without Lung Involvement_

Of the group without lung involvement nothing further would seem necessary to be said in addition to what one finds in standard text-books describing the disease picture of former epidemics. The incidence of influenza of this type among our group was as follows: Of 153 soldiers 93, or about 60 per cent., had a so-called simple, uncomplicated influenza, and of the 394 civilians 185, or about 52 per cent., had no lung involvement. There are a few points in which the symptoms of the present epidemic seem to be so peculiar that they merit special consideration.

_The Temperature_

This can be described as showing a sudden rise to 102–104, at which point it is maintained for a few days, and subsides by lysis in a few days more. A typical chart is as follows:

CHART I
]

Or the temperature might fall one or two degrees for a day or so after the first rise, and then go up again for one or two more days, and subside by lysis as is shown in Chart II.

CHART II
]

This would occur without our being able to find any lung lesion unless we accept the acute œdema or wet lung as a complication, and this we were rarely able to recognize by any definite physical signs in the chest. Cyanosis frequently accompanied this second rise of temperature, and was later interpreted as being associated with the so-called wet lung. When the temperature remained up longer than five days it could safely be concluded that lung involvement must be present.

_The Pulse and Respirations_

The pulse was invariably slow, or rather out of proportion to the temperature. Even when the patient seemed very ill the pulse remained from 84 to 96, and of surprisingly good quality. This was noted also when some of the more severe pulmonary involvements or some complications arose. The pulse frequently did not become rapid until shortly before death. The respirations in an uncomplicated case also remained about normal. The rate was not accelerated until lung complications arose, and then a gradually increasing rate was often the first herald of oncoming danger and a sign of grave prognostic import. The relation of the pulse phenomena toward the end of a fatal case was most remarkable. The respiratory rate was accelerated, as has been noted above, but the pulse rate frequently remained unchanged, being characteristically slow. In a patient seen in consultation with Dr. Lester H. Botkin, of Duquesne, Pa., death took place while we were in the sick room. It was a case of apparently uncomplicated influenza of seven days’ duration. The respirations were rapid and the pulse was only 96. In the last five minutes of life the heart beats as observed with the stethoscope never varied, until they suddenly ceased; during the same time the respiratory efforts were only three agonal ones, the last being a minute or so before the last heart beat. There were no physical signs of consolidation at any time recognized in this case, but we feel that the lung, had we seen it at autopsy, would in all likelihood have shown the peculiar hemorrhagic and œdematous character so often observed in the fatal cases.

There were, of course, marked exceptions to the description of slow pulse and later rapid respirations observed. In some the pulse rate and respirations increased, together with or without definite signs of a grave complication.

_Cyanosis_

This was recognized early in the epidemic. It was sometimes preceded by a peculiar flushing of the face, such as accompanies belladonna poisoning. It might be noticed in the very first days of the attack. The cyanosis was looked upon as being a very early symptom of lung involvement. With our later knowledge from autopsies, and especially as shown by Dr. Klotz, we feel it was surely an accompaniment of, or may even have preceded, the changes in the lung which have been designated as œdematous, “wet” or cyanotic. At the earliest appearance of the cyanosis we were frequently unable to find any change in the physical signs of the chest. Of course, the indefinite signs of an acute bronchitis were present, and in some cases an additional “impaired resonance” was noted over one or both lower lobes, but when this was definitely present other more definite signs soon followed, and our case was shifted suddenly from Group I, i. e., without apparent lung involvement, to Group II, i. e., with definite lung involvement. This cyanosis was noticed first in the face, and frequently was marked on the dorsal surface of the hands. It was not unlike the cyanosis which may sometimes be seen when large doses of certain coal tar derivatives are taken. In fact, the question arose whether in the epidemic of 1889 and 1890, when the coal tar derivatives were prescribed with such freedom and with accompanying cyanosis and apparently such deleterious effects, the cyanosis may not after all have been due more largely to the infection than to the medication. After that epidemic it was said: “Influenza has slain its thousands, but the coal tar products have slain their tens of thousands.” There was no gross hæmaturia or hæmoglobinuria present in these cases, although a few red blood cells were seen microscopically. There was, however, epistaxis, sometimes early in the disease or later associated with the cyanosis. In a few cases there was hæmoptysis, which we regard as always arising in cases where the wet or hemorrhagic lung was present. Cyanosis in disease of the lungs, and especially in the terminal stage of lobar pneumonia, is a familiar and common occurrence, but the cyanosis observed in this epidemic seemed quite different from the ordinary. The points of difference were these: (a) it came early in the disease; (b) it seemed to be more generally present when very little lung involvement could be demonstrated physically, and was just as likely to disappear when more definite chest signs were demonstrable; (c) it was not associated with embarrassment of respiration; (d) it had no relation with a demonstrable circulatory disturbance. The pulse did not become rapid; the quality of the pulse did not change; _the right heart was not dilated_, as is so frequently the case in the terminal stage of a lobar pneumonia when cyanosis appears; (e) and finally there was no associated œdema of the lungs, or at least that œdema of the lungs which occurs in the later stage of lobar pneumonia, when the pulse becomes rapid, when there is rapid and labored respiration, when the right heart dilates, when there is cold perspiration, and when the signs of impending death are plainly evident. The cyanosis of influenzal pneumonia seemed to be due to an entirely different cause or combination of conditions from those present in lobar or pneumococcic pneumonia. The cyanosis of influenzal pneumonia was, therefore, most confusing, and became all the more so when it was recognized that it did not yield to the respiratory and circulatory stimulants usually employed when cyanosis is present. The inhalation of oxygen was resorted to rather routinely early in the epidemic. It seemed to temporarily influence the cyanosis, but the results were not permanent, and the outcome of the cases did not seem to be different from those in which oxygen inhalations were not used.

The blood pressure in those cases in which cyanosis was observed was invariably low. This seemed to be due to the infection, for in several private patients not belonging to this group of patients with previously known high blood pressures the blood pressure was observed as much lower throughout the course of the infection.

_Leucopenia_

The peculiar behavior of the white blood corpuscles will be discussed more fully in another paper of this series. Our remarks will deal more particularly with the clinical observations and interpretations. The leucocytes fell below the normal from the very onset of the disease; they varied very little regardless of great changes in temperature; they did not always increase, or if they did increase at all it was comparatively little, even in an extensive invasion of the lungs or in severe complications. Concerning the leucopenia we have no explanation to suggest, save that it is a clinical characteristic of the disease. Our first thought was that the infection came on so suddenly and profoundly there was no time for a leucocyte reaction. But when we recall other diseases associated with a leucopenia, notably typhoid fever, which does not come on with such suddenness, our explanation for the leucopenia of influenza does not seem to hold. The leucopenia must be simply a peculiar toxic blood reaction characteristic of the Pfeiffer bacillus invasion. Such an explanation has long been accepted in the Eberth bacillus infection.

_Asthenia_

A condition which was frequently noted by the patient was an indescribable weakness and prostration which appeared early, sometimes before any other symptoms were noted or before any elevation of temperature. The young soldier was in apparent perfect condition when he arose in the early morning. During the “setting up” exercises he did not feel so fit, and a few hours later appeared extremely weak. When his condition was called to the attention of the medical officers he was found to have a slight elevation of temperature and was sent to his bed.

In former epidemics, as also in this one, marked prostration was recognized as coming at the height of the disease and remaining persistently during convalescence. But it does not seem to be recorded as among the first symptoms.

_Influenza with Lung Involvement_

Of the group with lung involvement much may be written from a clinical standpoint, and much confusion may be brought about. Especially is this so if one has no definite idea of the pathology present, or if one enters into a discussion of the character of the infection—a point upon which there is as yet no unanimity of opinion. From the many reports which have been put forth from the base hospitals of the various cantonments, and also from the reports coming from civilian practice, it is evident that scarcely any two groups of laboratory men or any two individuals of those separate groups have the same idea as to the bacteriology and the pathology peculiar to this epidemic.

As long as there is this confusion and element of doubt in the minds of those to whom we are accustomed to look, the clinician must necessarily speak with considerable hesitancy, especially when he attempts to interpret the physical signs observed. In our own group the observations of Klotz, Guthrie, Holman and others have given us an interpretation of our clinical findings which, at present at least, is more or less satisfactory. We shall definitely keep in mind their observations and conclusions as we go on with the description of the physical signs of the chest in cases having lung involvement.

In the description of this group it will readily be seen that the lower respiratory tract stood the brunt of the infection. Of the 153 soldiers under our care, 60, or about 40 per cent., were recognized as having pneumonia. Of these, 34 had undoubted demonstrable signs, while 26 were questionable, and yet from the temperature and other symptoms we concluded there was a pneumonia. Of the 394 civilians, 189, or about 50 per cent., had pneumonia. Of this group there were again some 28 or 30 in which the diagnosis was doubtful, according to the ordinary way of making a diagnosis, but we felt sure from the temperature course that more than a simple influenza was present. In the description of the physical findings of the chest in these influenzas with lung involvement it will be readily seen why the diagnosis must sometimes be in doubt.

Before referring to the physical signs it might be well to describe the condition and general appearance of the patient when the lungs became involved. The patient who had been progressing with an apparently simple influenza, with no chest signs except those of bronchitis or tracheitis, occasionally slightly cyanotic, became more cyanotic, the elevation of temperature continued longer than three to seven days, or if it came to the normal began to rise again, his respirations gradually increased and the pain in the chest became well localized. One could safely assume that the patient had developed a lesion in the chest. This could not always be localized during the first few hours or on the first day. The evidence of increased bronchial disturbance was frequently recognized, and later impairment of resonance and diminished breath sounds associated with “a few crackles” were noted. This, so far as we can tell, may have been the only evidence of the stage of œdema or “wet lung.” After this, as the disease advanced, definitely increased vocal fremitus and rather definite tubular breathing with greater impairment of resonance were noticed. These signs were usually observed first at the apex of the left lower lobe, and from here they extended forward along the inter-lobar sulcus, or downward along the spinal column. If the lesion was noticed first on the left side, in a day or two it was found more or less definitely in the right lower lobe also. It seemed to occur more frequently first in the body of the right lobe, instead of in the apex of the lobe as on the left side. In both lobes it might spread to contiguous areas and form a massive consolidation, or it might be found in small separate areas, some of which would clear up in a day, while others would persist.

The expectoration was frothy, containing either blood or masses of yellowish, greenish purulent material floating in a watery sanguiolent or clear fluid, or enmeshed in frothy mucus. The amount of expectoration in some cases was enormous, but as a rule it was scanty. It was thick and ropy at times and distinctly annoying to the patient.

At this stage the physical signs were very much in accord with those of broncho-pneumonia. In a few hours sometimes, or in a day, the small areas of consolidation became confluent and massive consolidation was formed. It appeared as though the whole lobe would in time become solid, as in a true lobar pneumonia. Or the original areas may apparently have cleared and other areas involved, became the centers of massive consolidations. In many cases both lower lobes were thus similarly affected, and one had the physical signs of a double lobar pneumonia. However, nearly always a small angle of the lobe remained clear, thus differing from the entire lobe involvement characteristic of a true croupous pneumonia. Other signs, such as the absence of vesicular breathing and presence of the crepitant râle, moist râles of all sizes to very coarse râles, could be noted. As in certain stages of a complete consolidation, the lung might be dry; no râles present, but definite tubular breathing present. This in a day or two, or after a longer time, might give the signs of resolution. The stage of resolution, however, was almost invariably prolonged, sometimes extending over weeks. With these variable lung signs were often mingled the signs of a fibrinous or serofibrinous pleurisy, which occasionally but remarkably infrequently went on to effusion or empyæma.

As stated above, the demonstrable pathology was in the lower lobe, and more frequently in the left than in the right, only occasionally in the middle lobe, and never, we might say, in the upper lobes. The very earliest definite signs were found at the apex of the left lower lobe.

This observation seems to be entirely contradictory to that of the pathologist, who found in 65 per cent. of all cases coming to autopsy a lesion in all the lobes of the lungs (Klotz). The only explanation we can give which seems at all satisfactory to us is that the pathology in the upper and middle lobes must not have been sufficient, or must have been of such a nature that it did not yield the physical signs, i. e., definite impaired percussion resonance, increased vocal fremitus and tubular breathing, with varying shades of moist râles—signs upon which we insisted before we were willing to state definitely that there is a demonstrable pneumonia present.

In this description it has been attempted to follow the order of invasion in a lung which seemed to go through the entire course of the disease. There were, necessarily, all degrees of the process, some cases showing few signs and yet being remarkably ill, and others all of the signs with very little other evidence of serious illness.

We were continually impressed with the notion that the pathology in the lung, at least the pathology demonstrable physically, did not tell the whole story of the case, and that the outcome depended as much or possibly more upon a general infection or toxæmia of which the recognized condition in the respiratory system was only a small part. We were particularly impressed with this in the success or failure following the application of any therapeutic measures. It was quite a common remark, therefore, in the wards of the hospital among those associated in the work that “the patient died too quickly to permit of the succession of the various stages of pneumonia”; or, in the autopsy room, that if the patient had lived long enough he would have had demonstrable, well-recognized pathology of the lung, instead of the cyanotic, wet, spongy lung which was found.

The temperature course in the pulmonary cases was characterized by its irregularities, and by its being entirely out of harmony with the extent and severity of the lung invasion in so far as it could be interpreted by the physical signs. The temperature as described in a simple influenza might not come to the normal in the time of three to seven days, and might even go higher, with no demonstrable chest signs, but with every other evidence of lung involvement. Later the temperature might come down by lysis, which was the usual way, and the chest signs gradually or suddenly become evident. The temperature might remain normal throughout the rest of the course, and a lobe or even both lower lobes of the lungs be as solid as in a true lobar pneumonia. Occasionally the temperature fell by crisis, but there was no associated change in the physical signs of the chest. In short, the temperature seemed to run a course entirely independent of the physical signs in the chest. In two remarkable cases seen in consultation on two consecutive days the physicians in charge declared that no signs of consolidation could be found, though all other evidences of pneumonia were present. In the 12 hours which had elapsed from the time the last examination was made the temperature fell by crisis. At the consultation, to the surprise of the family physicians, we found both lower lobes consolidated, it having occurred apparently with the crisis. Both patients were healthy-looking, robust, young men, and both recovered with delayed resolution. In the convalescence of such cases, if the patient got up too soon or if any other indiscretion took place, a relighting of the lung occurred. From the above description it can be readily seen that a diagnosis of the conditions in the chest in influenzal pneumonia was frequently impossible, because one had to abandon all his previous ideas of pneumonia, in so far as onset, crisis, blood picture, sputum, temperature, respiratory and circulatory phenomena, physical signs and prognosis were concerned.

Assistance from the laboratory was meager, especially in the early days of the epidemic. This was due largely to the inability to get laboratory workers in sufficient numbers to follow the work through, but more largely to the fact that we were unable to interpret the unusual laboratory results which were available. When we were once fully aware of the difficulties in diagnosis which confronted us, we utilized every practical means at our disposal. Among these was an examination of the chest with the X-ray. On account of lack of facilities and of help, it was impossible to make routine X-ray examinations of the chest in all cases. Besides, it was difficult to interpret the X-ray findings, on account of the unusual character of the lesions. Also, many of the patients were so desperately ill one hesitated to disturb them. We hear that other clinics had similar experiences, and that very little substantial help came from the X-ray, except in cases with complications. Several attempts were made to determine the kind of shadow, if any, the “cyanotic, œdematous, wet” lung would make, but no satisfactory observations have been forthcoming. From our own observations and from the discussions of other observers, it would seem to us that the stereoscopic examination of these chests is the only possible way of getting satisfactory plate readings in these cases where the pathology seems so lawless in its extent and peculiar in its distribution. This method of examination, however, demands facilities convenient at the bedside and perfect co-operation of the patient—difficult conditions to meet under the circumstances. In the acute cases, when the desire to make a diagnosis not only of the presence but of the extent of the disease was keen, X-ray examination was largely impractical. In cases of delayed resolution, or in cases with complications with prolonged convalescence, X-ray examinations were extremely helpful.

_Diagnosis of Influenzal Pneumonia_

In the consideration of any disease the well-trodden path of a painstaking history, a thorough physical examination, and reliable laboratory investigation, together with an intelligent interpretation, will usually lead to a definite diagnosis. In certain diseases, as is well known, the stress must be placed about equally on all of these factors, while in others one or other factor predominates. In influenzal pneumonia, until more is known of the etiology (bacteriology) and of the pathological changes and of the physiological disturbances, the controlling factor in the diagnosis (we feel embarrassed to admit) must be the history. This is true not only of the diagnosis of influenza with or without pulmonary involvement, but is also true of the diagnosis of the various complications, and will be found to be particularly true in the recognition of the bizarre sequelæ, which no doubt in the succeeding months or years will be attributed to or will follow in the train of influenza.

With the knowledge that there is a prevailing epidemic of influenza and that the manifestations are largely in the respiratory tract, any pulmonary disturbance will necessarily make one suspicious of the presence or the oncoming of an influenzal pneumonia in the patient under consideration. The history of the onset, as of simple influenza, is the greatest factor. This with a continued temperature, cough, cyanosis, slow pulse, continued asthenia, or even an unusual leucopenia, may have a greater weight in determining the diagnosis of lung involvement than will the apparently definite or, as it may happen, the confusing chest signs. To differentiate from ordinary bronchitis, broncho-pneumonia and catarrhal pneumonia, one need only refer additionally to the severity and persistency of the disease when it is of the influenzal type, as compared with the mildness of the ordinary type. To differentiate it from croupous pneumonia, one need only compare the confusing symptom picture of the influenzal pneumonia with the definite, clear picture of ordinary pneumonia; or the confusing kaleidoscopic chest signs of the one with the definite, clear-cut signs of the other. The laboratory thus far has been the smallest factor in making the diagnosis, in that sputum examinations, blood examinations, blood cultures and urine examinations are mostly negative in their results, or at least the findings are not specific. We do not, however, mean to indicate that these tests are not of the greatest value. The leucopenia is the one outstanding feature which seems to have separated this infection from other acute lung infections, excepting miliary tuberculosis. The differentiation of influenzal pneumonia from an acute tuberculous process in the lung may be difficult, especially if there is no reliable history available. However, the fact that pulmonary tuberculosis usually begins at the apices of the lungs and influenzal pneumonia at the bases or at the apices of the lower lobes is quite helpful. Of course, the examination of the sputum for tubercle bacilli will be a deciding factor.

The differentiation between influenzal pneumonia and diseases of the pleura is one which practically rarely needs to be made, for there seem to be very few cases of influenzal infection of the lungs in which the pleura is not also involved to a greater or lesser extent.

_Complications_