Chapter VIII: Section II: Influenza Epidemics Since 1893 (1)

In this section of our report we will describe with as great accuracy as our sources of information will permit, and in as great detail as space will allow the events which have led up to the epidemics of 1918–20 and the various phases of the epidemics themselves. Points of similarity with previous epidemics will be made obvious; the differences, when of significance, will be described and studied in detail.

OCCURRENCE SINCE 1893.

Attempts even today to determine when and where influenza has prevailed in the world since the great pandemic of the last century are met with great difficulties. There are several reasons for this, chief among which is the absence of definite characteristics by which the disease may be recognized. The isolated solitary case baffles positive diagnosis. Nearly every year there are reports in the literature of small outbreaks in institutions or communities in which the clinical picture is that of epidemic influenza. As a rule the conclusion has been in these cases that because the bacteriologic findings did not show a predominance of Pfeiffer’s bacillus the epidemic was not true influenza. This is particularly true in the outbreaks in which the streptococcus predominated. Today our views concerning the bacteriology have changed distinctly, and I believe it is safe to say that the predominance of a streptococcus in a local epidemic in no way rules out influenza, and that the only criteria by which we may judge are the clinical picture and the evidence of high infectivity, together with the epidemiologic characteristics of the local outbreak.

_Period 1893–1918._—A review of the medical literature between 1889 and 1918 gives one a certain impression which may be summarized as follows: Between 1890 and 1900 the disease was in general more highly prevalent in most localities than at any time during the preceding thirty years. At no time during this decade did the annual death rate from influenza in England and Wales fall to anywhere near the figures that had prevailed consistently between 1860 and 1889. Between 1900 and 1915 there was a gradual diminution, but still not to the extent that had prevailed previous to 1889. Since 1915 there appears to have been a gradual increase. During the entire period there has been difficulty in distinguishing between the disease in question and other respiratory tract infections, particularly coryza, sore throat, tonsillitis, and bronchitis. Many of the local epidemics which appear probably to have been true influenza have had associated with them a high incidence of sore throats. We describe this as sore throat, rather than tonsillitis, because the clinician remarks that although the throat is sore there is little if any demonstrable inflammation of the tonsils.

Chart VIII published by Sir Arthur Newsholme, showing the death rate per million of population from influenza in England and Wales gives some idea of the prevalence of the disease in the first part of the interpandemic period in those countries. It should be remarked that the record is for deaths from influenza only.

For records in this country it is convenient to refer to the death rate in the State of Massachusetts; first, because the records in that State have been carefully kept for a long period; and second, because influenza has been carefully studied in this State during both epidemics by two most competent epidemiologists. For the period preceding 1889 we quote herewith from Abbott:

“For the past 45 years or more, or during the period of registration which began with the year 1842, no epidemic of influenza has prevailed within the State to such an extent as to have manifested itself in any serious manner in the annual lists of deaths. An examination of the registration reports for each year since 1842 shows that in no year were recorded more than 100 deaths from this cause; the highest number from influenza in a single year (92) occurred in 1857, and the least number (8) in 1884. The average annual number of deaths from this cause reported in the State for the period 1842 to 1888 was 38. The average number during the first half of this period was greater than that of the last half, especially when considered with reference to the increase of population. From these statistics of nonepidemic influenza between the years 1842 and 1888 it appears that its greatest prevalence, or rather the years in which the mortality from this cause was greatest, were also years of unusual mortality from pneumonia, and in some instances from bronchitis.”

Frost has charted the death rate per 100,000 from influenza and from all forms of pneumonia in Massachusetts by month, from 1887 to 1916. From it he concludes that the epidemic of 1889–1892 developed in three distinct phases, the first culminating in January, 1890, the second in April and May, 1891, and the third in January, 1892. The mortality was higher in 1891 than in 1890, and still higher in 1892, while in 1893, although there was no distinct epidemic, the pneumonia mortality for the year was even higher than that of 1892. Frost remarks that this corresponds to the experience in England, and that it apparently represents the general experience in other countries (see charts IX and X).

CHART VIII.

Death rates per million from influenza in England and Wales from 1845
to 1917. (_Newsholme._)
]

CHART IX.

Monthly death rates per 100,000 from influenza and from pneumonia in
Massachusetts from 1887 to 1916. (_Frost._)
]

CHART X.

Monthly death rates per 100,000 from influenza and pneumonia in three
cities of the United States from 1910 to 1918, inclusive. (_Frost._)
]

In the absence of comparable statistics for Massachusetts in 1917 and 1918, Frost has studied for those years certain other localities, particularly Cleveland, San Francisco and New York City. The mortality in all of these places, as well as in Massachusetts, was fairly regular from 1910 to 1915, but in December of the latter year and January of 1916 there occurred in New York and Cleveland a sudden sharp rise in mortality. This was not shown distinctly in the San Francisco curve, but it was a rise which was almost universal and synchronous over the entire registration area. It is of interest as indicating the operation of some definite and widespread factor, and suggesting in this group of diseases an epidemic tendency which is perhaps, as Frost remarks, not sufficiently appreciated. In January of 1916 he found that influenza was reported to be epidemic in twenty-two states, including all sections of the country. The epidemic was very mild. In the early spring of 1918 there was another sharp rise, which we shall discuss in greater detail later.

_Increase in 1900–1901._—Reference to Frost’s chart for Massachusetts shows that there was also a rise in the curve around 1900. At this time influenza was quite widely disseminated. Early in 1901 the Marine Hospital Service made a canvass of all the states and several foreign countries to determine the epidemic prevalence of influenza. The results of the canvass were published in the Public Health Reports. The records lack the detail, particularly in the description of clinical symptoms, that is desirable in arriving at an identification, but the universal agreement from all individuals reporting, in the comparatively high morbidity and remarkably low mortality, together with the widespread distribution, and the duration of the local epidemic leaves little doubt as to the identity.

Influenza was reported present in October of 1900 in Los Angeles, Milwaukee and New Orleans. In November it became prevalent in Toledo and Cincinnati and in New York City. In December the disease was present in Chicago, Albany, Philadelphia, San Francisco, Denver, Baltimore, Grand Rapids, Columbus, O., Portland, Me., Detroit, Albuquerque and Omaha. In January it was reported in New Haven, Boston, Washington, D. C., Indianapolis, Louisville, Ky., Wilmington, Del., Portland, Ore., and Juneau, Alaska.

Although the disease was mild, in some localities a high proportion of the population was attacked. Thus in New Haven it was estimated that 10 per cent. developed the disease, and in Los Angeles 20 per cent., while in Wilmington, 40,000 were estimated to have become ill. In certain small towns in Texas the incidence was especially high. In Pittsburgh, Texas, ten per cent.; Laredo, 15 to 20 per cent.; Hearne, 50 per cent.; and El Paso, 50 per cent. were attacked. The duration of the epidemic in most localities was from four to six weeks.

Thus we see that in October, November and December of 1900 and January of 1901 there was a widespread epidemic affecting all parts of the United States. Many additional records in the Public Health Reports coming from small towns have not been included in this summary.

At the same time an attempt was made to determine the prevalence in foreign countries and letters were sent to the various United States Consulates. It was discovered that the disease was mildly epidemic in Denmark in October, in Berlin in November, in Cuba, British Columbia, Ontario, Egypt, Paris, Mexico and the West Indies in December; in Flanders, Porto Rico, Honolulu, in January of 1901; in Malta in February, 1901; and in London and Ireland in March of that year. The following countries reported that they had no influenza at the time: Windward Islands, Jamaica, Bahamas, Brazil, India, Colombia, Costa Rica, Ecuador, Honduras, Persia, Philippine Islands, Spain, Switzerland. The disease was reported as being not of epidemic prevalence in the following localities: Marseilles, Paris, Bremen, Hamburg, Mainz, Stuttgart, Bristol, London, Liverpool, England as a whole, Scotland, Amsterdam, Naples, Constantinople.

Reports from Switzerland and from Brazil stated that there had been no influenza since the pandemic period 1889–1893. The death rate per 100,000 in Glasgow from influenza for 1896 was recorded as six; for 1897, twelve; for 1898, fifteen; 1899, twenty-two and for 1900, twenty-seven.

The disease was present in Lima, Peru in March, 1900, and at Malta in the same month. In Prague it was stated that ten per cent. of the population had been attacked in the winter of 1901. In Sivas, Turkey, fifty per cent. of a population of 50,000 were estimated to have been taken ill within the winter months. It was reported from Valencia, Spain, that there had been four or five visitations of influenza since the preceding pandemic, each recurring invasion presenting a milder and less expansive form than its predecessor. Very few deaths had been recorded as directly due to influenza, but an increased mortality followed the epidemics. In normal times the average mortality was ninety deaths per week. After a visitation of influenza the number had increased to as much as 160 per week. The population numbered 204,000.

_Period from 1901 to 1915._—Between 1900, with its wide distribution of a very mild influenza, and 1915, there is very little mention of epidemic prevalence of the disease. References which appeared in the Public Health Reports during the interval are characterized chiefly by their brevity, and by the absence of descriptive detail. They should nevertheless be included.

In October of 1901 there was some increase of the disease in the Hawaiian Islands, 110 cases being reported on the island of Kauai.

At the same time, C. Williams Bailey reported a mild form of influenza existing in Georgetown, S. C., which was first considered to be hay fever in consideration of the presence of the rice harvest season, but which was finally decided, after careful investigation, to be true influenza.

On July 21, 1902, the U. S. Consul at Canton, China, telegraphed that influenza “was almost epidemic, plague sporadic in Canton.”

In 1903 the disease was reported as apparently prevalent at New Laredo, Texas.

Surgeon Gassaway, of the Marine Hospital Service, reported from Missouri, December 14, 1903, as follows: “There is a very decided increase in the number of cases of influenza in this vicinity. Two have been admitted within the last few days to this hospital, and several cases have appeared among the patients under treatment. In these cases the onset is sudden and the disease appears principally, at least at first, to be confined to the nose and throat.”

Measles and influenza were reported prevalent in Barbados, West Indies, during the month of December, 1904.

Sturrock describes a quite typical local epidemic in a British institution in 1905.

Influenza was epidemic in Guayaquil and various other places in Ecuador during the months of June and July, 1906.

Selter speaks of a true local epidemic of a disease clinically resembling influenza which occurred in 1908 and extended over the territory from France to the Rhine.

Hudeshagen mentions having examined bacteriologically cases of influenza in the year 1914.

Ustvedt relates his experience at the Ullevaal Hospital up to September, 1918. Since 1890 there had been cases reported every year from the high marks of 10,461 cases in Christiania in 1890 and 5,728 in 1901 to the lowest figure, 138 in 1906. “The cases listed as influenza in the last few years may have been merely a catarrhal fever. This is the more probable as the cases were restricted to the winter months, while influenza usually occurs at other seasons.”

Jundell believes that influenza is endemic at Stockholm, Sweden, hundreds of cases being reported there each year. During the years 1912–1919 Pfeiffer’s bacillus has been found in ten per cent. of those cases in which the diagnosis seemed certain.

A current comment in the Journal of the American Medical Association in 1912 remarks that epidemics of coryza, sore throat, and bronchitis usually have been called influenza or grip because of the characteristic contagiousness and the infectivity, the persistence of the symptoms, and the tendency to prostration and mental depression. But this diagnosis has not been satisfactorily confirmed by bacteriologists. An epidemic according to the Journal, which occurred in Boston and which was called sore throat, was studied by Richardson and others. They traced the contagion to a streptococcus which apparently was spread by means of milk. Müller and Seligman had recently carried out a study of an influenza epidemic among children in Berlin and concluded that the causative organism was a streptococcus, differing so much from the ordinary germ that they used the term “grip streptococcus.” Davis and Rosenau, according to the comment, had made a bacteriologic study of a recent epidemic of sore throat in Chicago, and had demonstrated as the exciting agent a streptococcus of peculiar characteristics, which in many respects resembled the organism described by Müller and Seligman. The Journal noted that these three epidemics occurring during the years 1911 and 1912 in widely separated communities were all caused by the streptococcus, and cautioned against the proneness to call all such epidemics grip. Today the predominance of the streptococcus would not necessarily rule out influenza in our minds.

In the winter of 1913, C. L. Sherman had occasion to study carefully fourteen cases of so-called influenza in the vicinity of Luverne, Minnesota. Bacteriologic smears and cultures were made from the throat and sputum in all cases. Bacillus influenzae was found in two of the fourteen; pneumococcus in four and streptococcus in all. Tubercle bacilli were found in one case. The onset of the disease was invariably abrupt. The fever in all cases ranged between 101° and 104°; symptoms indicative of infection of the upper respiratory tract were always present. There was more or less sore throat in all. There was either cough at the onset or else it appeared within 48 hours. Headache was complained of by twelve of the fourteen; pains in the back and in the limbs by thirteen, and nervous symptoms by six. Prostration out of all proportion to the fever and other symptoms prevailed. Two developed an otitis media and the streptococcus was isolated from the purulent discharge in both cases. One patient had a complicating empyema, and one an acute arthritis. Sherman also concluded that we are prone to call too diverse diseases influenza.

Walb stated in 1913 that at Bonn during the preceding years there had been numbers of cases of a febrile affection which seemed to be typical influenza, but for which the pneumococcus appeared to be responsible. They were never able to isolate the influenza bacillus, and according to their statement the Hygienic Institute at Bonn, as well as that at Berlin, had not “encountered an influenza bacillus within the preceding ten years.”

C. T. Mayer described in 1913 a case of influenza in Buenos Ayres which is of particular interest in view of one of the symptoms, cyanosis, which was so prominent a feature in 1918. This appears to have been an isolated case. The diagnosis wavered between miliary tuberculosis and pneumonic plague, because of the high fever and intense cyanosis, with nothing to explain the cyanosis on the part of the heart. There were signs of severe congestion of both lungs, and notable enlargement of the spleen. Bacteriologic examination was negative except for the presence of Bacillus influenzae and Micrococcus catarrhalis. The patient subsequently improved rapidly, and the lungs were entirely normal after thirty days, thus ruling out the other two diseases.

A London letter to the Journal of the American Medical Association dated February 5, 1915, runs as follows:

“Since the outbreak of the war the public health has been remarkably good, but the record is now being threatened in the case of London, at any rate, by an epidemic of influenza.

“The gastric symptoms which distinguished last year’s epidemic are absent. The disease is most infectious. Whenever it has seized the individual it has usually run through the entire household.

“Whole offices have succumbed, and as the mildness of the attack lures the sufferer to continue his normal occupation, the disease has a full opportunity of extending. A large number have resulted in pleuro-pneumonia; otherwise the chief symptoms are headache, fever, tonsillitis.”

Telling and Hann describe another clinical diagnosis of influenza, the diagnosis being concurred in by Sir James Goodhart and Sir Clifford Allbutt. The onset was absolutely sudden at a supper party on November 10, 1912. The patient had a slight rigor, and was compelled to go to bed. In the night he had a longer and more severe rigor, with a temperature of 103°. On the following morning he dressed, but another chill sent him back to bed with a temperature still 103°, pulse 110, regular, and remarkably dicrotic. There was no cough and no sore throat. Another chill occurred in the evening. On November 12th the patient had two chills, the temperature remaining steadily at 103° to 104°. The patient complained much of nausea but did not vomit. On November 13th the temperature remained up, there was no chill on this day; the spleen was large and easily felt for the first time. On the 14th note was made that there was no headache. On the 15th, 16th and 17th the temperature began to fluctuate. On the 18th there were two severe rigors, and by the 19th the temperature suddenly fell to normal, with drenching sweat. Throughout there was nothing to suggest pneumonia, and typhoid fever appears to have been successfully ruled out.

An epidemic of influenza which prevailed in the city of Pittsburgh, Pennsylvania, from December to February of 1907 and 1908, has been described by J. A. Lichty. He says that the epidemic was as widespread, though probably not quite as severe, as the pandemic of 1889. Whole families, including servants and all associated with the household, were afflicted in rapid succession. The onset was sudden and severe, the usual symptoms of pain, all over, being most pronounced. The temperature did not go unusually high, nor did it seem to be in accord with the severity of the symptoms when the patient took to his bed. In typical cases the attack lasted from two to three or four days. Peculiar to this epidemic seemed to be the general complaint of sore throat. Upon examination the throat rarely showed any other evidence of an abnormal condition than a rather dark cyanotic blush, which was most intense over the tonsils and faded out over the roof of the mouth. This was rarely associated with any swelling or fever. Sinusitis and otitis media seem to have been the two most frequent complications. The disease appeared to be particularly fatal for chronic invalids. It was highly contagious. Many of those physicians who were frequently exposed to the disease fell victims.

At the same time C. H. Jones described an epidemic of the same disease in Baltimore. The symptoms were described as headache, backache, limb-ache, with a slight elevation of temperature, seldom more than 102°. Catarrhal symptoms developed secondarily and were not so prominent a feature as in former epidemics. There were some gastric symptoms, usually consisting of vomiting and nausea. Jones quotes no statistics, but feels sure that the infection was more extensive than at any period since 1895.

Coakley and Dench describe throat and ear complications as they saw them in New York. From this we may assume that the disease was present at the same time in New York City.

The following chart, derived from the U. S. Vital Statistics Report shows the increase in the death rates from influenza in 1900 and 1901; that of 1907 and 1908, and finally an increase to 26.4 per 100,000 in 1916, which reflects the epidemic beginning in the latter part of 1915:

_Influenza and Pneumonia Mortality in the United States Registration
Area for Each Year Since 1900._
═════════════════╤═════════════════════════════════════════════════════
Year. │ Annual death rates per 100,000.
─────────────────┼─────────────────┬─────────────────┬─────────────────
„ │ Pneumonia. │ Influenza. │ Combined
│ │ │ diseases.
─────────────────┼─────────────────┼─────────────────┼─────────────────
1900│ 158.6│ 22.8│ 181.4
1901│ 133.5│ 32.2│ 167.7
1902│ 124.7│ 10.1│ 134.8
1903│ 122.6│ 18.5│ 141.1
1904│ 136.3│ 20.2│ 156.5
1905│ 115.7│ 18.8│ 134.5
1906│ 110.8│ 10.3│ 121.1
1907│ 120.8│ 23.3│ 144.1
1908│ 98.8│ 21.3│ 120.1
1909│ 96.3│ 13.0│ 109.3
1910│ 147.7│ 14.4│ 162.1
1911│ 133.7│ 15.7│ 149.4
1912│ 132.3│ 10.3│ 142.6
1913│ 132.4│ 12.2│ 144.6
1914│ 127.0│ 9.1│ 136.1
1915│ 132.7│ 16.0│ 148.7
1916│ 137.3│ 26.4│ 163.7
─────────────────┴─────────────────┴─────────────────┴─────────────────

At best our information for these years is unsatisfactory. It is greatly to be desired that individuals who have access not only to the current medical literature, but also to the vital statistics and other records for all countries possessing reliable records, and who are versed in the newer mathematical methods of demography, establish definitely the influenza prevalence and distribution during these interpandemic years. The difficulty in this work is that mortality statistics are unreliable and morbidity statistics are lacking.

_Influenza in 1915–1916._—Until the end of 1915 there was no widespread distribution in the United States similar to that of 1900 and 1901, but at that time there developed a widespread epidemic in this country of similar or possibly slightly greater severity than that of fifteen years previously. Reference to the last table will show that during 1916 the annual death rate from influenza as reported in the United States Vital Statistics reached the rate of 26.4 per 100,000. According to V. C. Vaughan the literature of that time shows that this epidemic originated in the West, first attracting attention at Denver, and gradually spread over the country.

Dr. Dublin of the Metropolitan Life Insurance Company gives the following table in which the deaths from influenza and pneumonia during the months of December, 1914, and January, 1915, are compared with deaths from the same cause during the months of December, 1915, and January, 1916:

═══════════════╤═══════════════════════════╤═══════════════════════════ Name of city │ Deaths reported as due to │ Deaths reported as due to │ influenza. │ pneumonia. ───────────────┼─────────────┬─────────────┼─────────────┬───────────── „ │ In 1915–16. │ In 1914–15. │ In 1915–16. │ In 1914–15. ───────────────┼─────────────┼─────────────┼─────────────┼───────────── Baltimore │ 57│ 12│ 219│ 101 Cincinnati │ 81│ 2│ 105│ 84 New Orleans │ 97│ 44│ 35│ 29 New York │ 494│ 62│ 2,067│ 1,207 Philadelphia │ 324│ 62│ 564│ 272 Providence │ 38│ 3│ 31│ 31 ───────────────┼─────────────┼─────────────┼─────────────┼───────────── Total │ 1,091│ 185│ 3,021│ 1,724 ───────────────┴─────────────┴─────────────┴─────────────┴─────────────

Dublin states that the Industrial Department of the Metropolitan Life Insurance Company, covering the entire country and embracing ten millions of people, had deaths in the periods above mentioned, as follows:

In December, 1914, and January, 1915, the number of deaths
attributed to influenza was 165

While in the corresponding months of 1915–1916 the deaths
attributed to influenza were 957

The deaths attributed to pneumonia in December, 1914, and
January, 1915, were 1,468

While the number of deaths attributed to the same cause in
December, 1915, and January, 1916, were 2,563

Coffey and others have reported an epidemic of influenza at Worcester, Mass. during the first three weeks of January, 1916. During the first three weeks of January, 1915, there were reported in that city twenty-two deaths from respiratory diseases, making a total of 14.9 per cent. of the total deaths. In the same period of 1916 there were reported ninety-three deaths from acute respiratory diseases in the same population.

Two of the more complete descriptions of the epidemic of the year 1915–16 are those by Mathers, and by Capps and Moody. Mathers reports that: “During the winter of 1915–1916 the United States was visited by a severe epidemic of acute respiratory infections which resembled in every detail the great epidemic of 1890. This outbreak was apparently first noticed in the Middle Western States, and it spread rapidly over the entire country, taking a heavy toll of human life. December and January were the months in which these infections were most prevalent, and the epidemic had almost completely lost its impetus by March, 1916. During the height of this epidemic in Chicago, sixty-one cases of the disease were studied bacteriologically, and the results form the basis of this paper.”

Mathers found hemolytic streptococci in forty-six instances, in all of which they predominated. Green producing streptococci were found thirty times, with one pure culture, and pneumococci thirty times with four pure cultures. Staphylococci were isolated in fifty cases; Micrococcus catarrhalis in six, and Friedländer’s bacillus in one case. The influenza bacillus was found in only one instance, and then in small numbers. The majority of the patients were studied early in the course of the disease, and in the earliest, hemolytic streptococci were almost constantly found, especially in the throat. In the atypical pneumonia which followed many of the attacks of grip, hemolytic streptococci predominated. In none of these was the Bacillus influenza found.

Mathers reported that coincident with the epidemic among humans there was an epizootic of so-called influenza among horses. The symptoms are very similar to that of the disease among humans. He isolated a streptococcus as the predominating organism in the horses. The streptococci from human and equine sources, although similar in many characteristics, differed widely in pathogenicity, and seemed to be highly parasitic for the specific hosts.

Capps and Moody found that in man most cases began rather abruptly, with coryza, pharyngitis, laryngitis, or bronchitis.

“The chief complications were inflammation of the accessory sinuses of the head, and bronchopneumonia, the latter being responsible for most of the fatalities. None of these symptoms taken alone would justify the distinctive name of grip. But the widespread and almost simultaneous onset of this fairly uniform symptom group and the rapid cessation of the epidemic after a few weeks reminded physicians generally of the great grip pandemic of 1889–1890. This resemblance was further strengthened by the unusual prostration lasting days or weeks after even mild attacks. The older practitioners can recall no similar epidemic during the twenty-five years intervening between 1890 and this year. The numerous epidemics of septic sore throat have all been entirely different in their symptomatology, and all were restricted to certain localities. The term “grip,” therefore, seems justified from a clinical standpoint.

“The public health reports offer evidence of an unusual prevalence of pneumonia in the larger cities. Nicolas calls attention to the fact that the incidence of grip was greatest in those cities in which the mortality from pneumonia was most strikingly increased.”

Capps and Moody found that as a rule the white blood counts in the individuals sick with influenza were 10,000 or less. A number showed true leucopenia. Less frequently there was a leucocytosis up to 15,000 or higher.

_Influenza between 1916 and 1918._—Zinsser cites Dr. George Draper, who believes that he observed at Fort Riley in the winter of 1917 epidemic cases of influenza. He believes that for Europe too there is evidence that influenza was endemic during the years preceding the great outbreak, and that a number of minor epidemic explosions had occurred in the years just preceding 1918:

“MacNeal who has investigated military reports particularly, states that small epidemics occurred in the British Army in 1916 and 1917. A chart constructed by him from the American Expeditionary Force reports shows that a considerable rise in reported influenza cases took place in November and December, 1917, and in January, 1918, gradually declining toward spring. MacNeal, compiling the data available in the office of the Chief Surgeon, A. E. F., states that the influenza morbidity reported per 100,000 for succeeding months in 1917, were as follows:

July 321
August 438
September 404
October 1,050
November 1,980
December 2,480

“Robertson, who studied many of the secondary pneumonias which came to autopsy at this time found an unusual type of lobular pneumonia in which Pfeiffer bacilli were frequently found. In many of these cases the organisms could be obtained from the nasal sinuses and antra. Similar findings were reported by British bacteriologists (Hammond, Rolland and Shore, and Abrahams, Hallows, Eyre and French), who studied the cases that occurred in the reports by Austrian physicians in reference to outbreaks of typical influenza on the Austro-Russian front early in 1917.

“There seems little doubt, therefore, that for some years before the pandemic of 1918 influenza was endemic in many parts both of Europe and of America. As early as 1915–1916 Frost finds evidences of limited epidemic outbreaks in the United States. During the winter immediately preceding the true beginning of the pandemic small outbreaks occurred among the allied troops in France, the British troops in England and probably among American troops gathered in home concentration camps as well. MacNeal in a summary of the conditions prevailing among American troops in France concludes that epidemic influenza in that country originated from the endemic foci there existing, and that the disease was probably carried from Europe to the United States by shipping. The former assumption; namely, that the epidemic occurrence of the disease may have been due to the fact that an enormous and concentrated newly introduced material of susceptibles may have been lighted into flame at the numerous endemic smoulders, may well be correct. The latter, however, concerning the transportation of the disease from Europe to America may justly be questioned. For, in the first place, Frost’s studies have shown that prepandemic outbreaks were quite as frequent in the United States as in Europe during 1915 and 1916, and, though we have no proof of this, there is reason to believe that influenza was prevalent in concentration camps during 1917.”

Carnwath, after remarking that the epidemic began in the British Army in France in April, 1918, says that according to the reports of the Influenza Committee of the Advisory Board this was not the first time that Pfeiffer’s bacillus had appeared in the armies. On the contrary, it had frequently been found in cases of bronchopneumonia, especially during the winter of 1916–1917. It is doubtful, however, whether much importance, from the epidemiologic point of view, attaches to these sporadic findings of the Pfeiffer bacillus.

Influenza was reported in the year 1917, but this year, as well as the epidemic of 1916, becomes involved in a determination of the date of onset of the great pandemic of 1918.

THE PANDEMIC OF 1918.

The date and site of onset of the great pandemic are subjects concerning which there is no conclusive information. There have been small outbreaks of clinical influenza with epidemic tendencies at one place or another during nearly all of the intervening years since 1889. In all of them the question is open as to whether they were true influenza, and also assuming that some were true influenza, how many of them should be so included. There are some who believe that the increase of morbidity following the measles epidemic in the United States Army camps in the winter of 1917–18 is genetically associated with the great pandemic. In short, there is no one point in the last few years at which we may say that influenza which had previously been non-existent started at a focus and spread throughout the world.

It follows from the experience of 1889 that we should at least attempt to find an endemic focus and to follow the progression of the disease. It is safe to say that once having become pandemic the disease spread as it did thirty years previously. Experience in this country, where the autumn spread began in the New England States and continued West and South; knowledge of the late spread to remote localities; the fact that the disease first appeared in England, etc. in sea coast towns; the introduction of the influenza into new countries at seaport towns, after the arrival of infected ships, all coincide well with the past history.

But which of the several local epidemics of the preceding years was the direct progenitor of the great pandemic? In order to follow more clearly the development of the facts we will record here the various hypotheses that will come up for consideration as to the site of origin of the disease.

1. Influenza is endemic in some one locality, such as Turkestan in Asia, from which place the disease spreads throughout the earth at intervals, after having acquired in some way greatly increased virulence. The local outbreaks of interepidemic times are not due to the virus which causes the great pandemics and should be called pseudo-influenza in contrast to influenza vera. Following the pandemic it is true, however, that for a succession of years local outbreaks occur, due to the pandemic virus which has been left deposited in small endemic foci. These disappear in the course of a few years.

2. The second hypothesis is similar to the first, except that in it is considered the possibility of there being more than one endemic focus, at least two, one in the old world and one in the new. Although Leichtenstern believed in the first hypothesis he did not deny the possibility of the second.

“There have been in the past several well described influenza epidemics limited to North America. Furthermore true pandemics have occurred at the same time in North America and in Europe. We can suggest the hypothesis that there is a permanent endemic focus, just as in central Asia and Russia, existing in the southern part of North America. The following facts concerning the last pandemic period favor this idea.

“As early as May, 1889, influenza began in Athabasca (British North America) and in the summer of 1889, in Greenland. It is especially interesting to hear of an extensive influenza epidemic which in the middle or toward the end of December, 1889, broke out in the Northwest Territory of British North America, in Manitoba, in the Island of Vancouver, similar to that in the east of Canada and Quebec. A spread of the epidemic, which attacked Boston and New York on December 17th, to the above territories, far away and connected by very poor transportation facilities, is certainly improbable, especially in consideration of the time at which the two epidemics occurred.

“We are told that the invasion and the outbreak of influenza in these vast territories occurred at practically the same time at such widely separated places as Fort MacLeod, Saskatchewan, Prince Albert and other military posts, and furthermore in isolated Indian camps and tribes between which there was little or no communication.

“These facts also indicate that we are considering primary endemic pandemics analogous to the one which broke out in July, 1889, in Central Asia.”

3. The virus of influenza is more or less uniformly distributed throughout the world. We may say that it is endemic in many localities, as is the case with the meningococcus. Quite frequently in one locality or another the virus acquires increased virulence and causes a small local epidemic which may even spread to adjoining territories. It is possible that the virus in two or more separated localities may become more invasive simultaneously, thus causing widely separated and unrelated outbreaks. As a rule the virulence does not become so great as to cause a true pandemic, but at rare intervals, usually of decades, or thereabouts, the epidemic virus becomes so greatly enhanced, perhaps from passage to new territory and through non-immune individuals, that it eventually commences on its wild career around the earth. Perhaps the _pandemic_ variety usually comes from one particular locality among the many endemic spots. Perhaps always from the same locality or perhaps at times even simultaneously from many different ones. It is possible even that an increased virulence develops simultaneously in all localities. This third hypothesis develops into a discussion as to whether the small interpandemic epidemics are true influenza or some other disease.

Again, Leichtenstern, although he does not favor it, recognizes the possibility of this theory:

“Whether the small local epidemics reported by Kormann in Coburg in 1878 and by O. Seifert in Würzburg in 1883 are the same as the true epidemic influenza is at present uncertain. Some of the complications, such as swelling of the neck glands, and especially frequently parotitis, purpura, scurvy, indicate that the epidemic in Russia, in 1856–1858, reported by Kasin, was not the true influenza.

“When W. Zülzer writes in 1886 of an epidemic in Berlin in which many thousands of individuals were attacked, the question might arise, is this the same influenza which three years later passed through the entire world and which in Berlin was believed by the same physicians to be a new disease?

“The evidence is better in the case of the epidemic reported by von den Velden in 1874–75. First, because of the complication with pneumonia and especially because at the same time the disease sprang up in several places in France, South Germany and the Rhine Provinces. It is very doubtful whether epidemics described in 1855 and 1862 in Iceland, in 1870 in Philadelphia, in 1875 in Scotland, in 1876 in the Fiji Islands, in 1887 in several places of England, in October, 1889 in Natal, in November, 1889 in Jamaica and Prince Edward Island, was the true influenza, even though the complications of pneumonia in the last named epidemics favor this assumption. As regards the influenza epidemic which attacked specially the school children of Pleshey and Great-Waltham and from which fifty per cent. became ill in November and December, 1889, whereas the pandemic was known to have begun there in January, 1890—the high percentage of school children that were attacked renders the conclusion that this was influenza very doubtful.

“It is an entirely different matter concerning the last epidemic in which the epidemiologic compilations, based on retrospective diagnoses suggest that in many places of Germany the ‘first case’ of even small epidemic outbreaks was observed as early as the summer and autumn of 1889; in other words, several months before the outbreak of the true pandemic in December.”

Leichtenstern believed that the so-called catarrhal fever and epidemics of “cold” which some have been accustomed to call grip or influenza are not the true disease, although he admits that there is no pathognomonic sign by which the diseases may be differentiated. He expected that search for the influenza bacillus which had recently been discovered would enable investigators to determine by its presence or absence whether or not these local epidemics are true influenza.

This, of course, would depend on the proof that the influenza bacillus is the cause of the disease. If the many local influenza outbreaks which Hirsch has collected in his exhaustive historical tables are the same disease as true influenza, then the picture of influenza must be considered as rather protean. Leichtenstern adds that this is a possibility which from present information we cannot deny. He writes: “If such is the case we must give the following epidemiological definition of influenza: Influenza is a specific, infectious disease usually occurring epidemically which, however, is endemic over the entire earth, as indicated by outbreaks of cases, and which, after years and decades have passed, breaks out in epidemic proportions. It is recognized nearly every year in one or another place on the earth where it becomes epidemic. From time to time from some point or center, or from several points, as for instance simultaneously in the old and new world, and for reasons unknown to us, an enormous increase in virulence of the specific virus occurs and with it a great increase in the contagiousness of the disease. Those are the times when influenza spreads in mighty epidemics over wide stretches of land and portions of the earth, or over the whole earth. Our common epidemic influenza or grip, occurring practically isolated or in very small outbreaks, belongs to the same type of disease as the pandemic variety, but is due to a mitigated form of the causative organism, one of decreased virulence and of shorter viability.

“_Provisionally, however, we will hold_ until the proof has been obtained by bacteriological methods that influenza nostras and influenza pandemica are two entirely different diseases, just as are cholera nostras and asiatica. Accordingly, we will divide the diseases designated as influenza in the following way:

“1. Influenza vera, caused by the Pfeiffer bacillus.

“2. The endemic-epidemic influenza vera which arises from the germ remaining after the spread of the influenza pandemic and which is caused by the same germ, the bacillus of Pfeiffer. The duration of this endemic state of influenza vera may last years in single localities.

“3. The endemic influenza nostras, or pseudo-influenza or catarrhal fever, commonly called grip, a disease sui generis. The germs causing this disease are at present as little known as are those of cholera nostras.”

Parkes, in 1876, recognized these possibilities: “The exact spot has not been made out. Two opinions prevail. First, one focus; second, many foci. Each nation, in turn, attributes the disease to its neighbor and from the names so given one can follow the direction of the epidemic.” Noah Webster believed that in 1698, 1757, 1761 and 1781 it originated first in America. Hirsch believed that some of the epidemics had probably originated in North America.

We find then that after the pandemic of the last century the same epidemiologic questions had arisen that have come into such prominence during the present period. As a rule those who have quoted the epidemiologists of 1890 to 1900 have mentioned the first hypothesis and have failed to allude to the fact that the other two were considered. So we see that the subject was by no means settled even at that time, and that if we should discover that the 1918 pandemic cannot be traced to a single endemic focus our results will not be absolutely contradictory to those of the last century.

Returning to a consideration of the period 1916–1918, we observe from reference to Frost’s diagram that in the spring of 1918 there was a sharp and general rise in mortality from influenza and pneumonia. Frost reports that in the larger cities on the Atlantic seaboard this increase occurred generally during January, February and March, when pneumonia mortality normally reaches its maximum. The increase was not so evident in all these cities as it was in New York City. In the rest of the country, especially in the Central and Western States, the increase occurred in April, a month during which pneumonia mortality is generally on the decline, and was sufficient to constitute an unmistakable departure from the normal. The increased mortality rate extended quite generally into May and in some areas still longer. This is the first increase after 1916 that is pictured in the mortality statistics for the country at large.

There are some who believe that they saw influenza in mild form in the United States army in the year 1917. V. C. Vaughan has investigated this possibility and from a study of the sick and wounded charts decided that there was no relation between influenza and the pneumonia which was prevalent in 1917, and which usually was secondary to measles, being caused by the streptococcus in the majority of localities. The lack of association between influenza and pneumonia in 1917 and the direct association in 1918 is well brought out by a comparison of the figures in the two following charts, prepared by V. C. Vaughan:

_Pneumonia as a Sequel to Respiratory Diseases._ (All troops in United States in 1917.) ─────────────────┬─────────────────┬─────────────────┬───────────────── │ │ No. of cases │ Per cent. of Primary diseases.│ No. of cases. │ followed by │cases followed by │ │ pneumonia. │ pneumonia. ─────────────────┼─────────────────┼─────────────────┼───────────────── Measles │ 47,573│ 2,075│ 4.37 Scarlet Fever │ 1,966│ 54│ 2.75 German Measles │ 8,982│ 39│ 0.43 Bronchitis │ 41,233│ 20│ 0.049 Influenza │ 32,248│ 19│ 0.059 Meningitis │ 1,027│ 13│ 1.27 Tonsillitis │ 43,021│ 7│ 0.016 Pulmonary │ 6,799│ 6│ 0.088 tuberculosis │ │ │ Laryngitis │ 4,633│ 2│ 0.043 Diphtheria │ 1,163│ 1│ 0.086 Mumps │ 21,725│ 0│ 0.000 Pharyngitis │ 8,096│ 0│ 0.000 ─────────────────┴─────────────────┴─────────────────┴─────────────────

_Influenza and Pneumonia in Last Four Months of 1918._
Number of cases of influenza 338,343
Number of cases of influenza followed by pneumonia 50,700
Number of deaths from influenza-pneumonia 17,700

Stallybrass, who has studied the influenza and pneumonia deaths in Liverpool, England, since the 1889 pandemic, states that in every year there had been reflected in the curves evidence of periodic increase in deaths from influenza and pneumonia, and he states that from 1914 onward there has been a progressive increase in the annual number of influenzal deaths with the single exception of 1917.

It becomes evident that we cannot with the information at hand find any one locality in which the disease was prevalent sufficiently ahead of the pandemic and to the exclusion of other localities, so that we might determine accurately the site of origin. The next step will be, then, to discover as accurately as possible the date at which various communities were first definitely attacked by the great pandemic, and to search out the locality first affected.

DATE OF FIRST INCREASED PREVALENCE IN VARIOUS LOCALITIES.

From table II which gives the earliest recorded dates of increased prevalence in different localities, we can gain a fairly accurate idea as to the direction and manner of spread of the disease during the pandemic. Influenza was first noticed in the United States early in March, 1918. By the end of the month it had become more disseminated in very mild form over many of the States east of the Mississippi and a few West of that line. The following month the disease appeared in France. In the American Expeditionary Forces in France it first appeared at the base ports which were receiving troops from the United States. During this month the disease had reached the allied Western front, the German front had become infected and probably the disease had started on its travel inward into enemy country. In May the disease was reported present in Scotland, Spain, Greece and Egypt. In June England became infected, as also Switzerland, Germany, Austria and Norway. In this month the disease had reached as far as South America and India. In China, on the 15th of June, there was reported an epidemic of a disease resembling dengue which affected fifty per cent. of the population in Chefoo and Shanghai. This disease may well have been influenza. During July the disease had spread through Germany, appearing according to German reports in the cities toward the West earlier than in Berlin and other more Eastern cities, including Vienna. In July the disease was present in other countries of Europe and was again reported in China and India.

TABLE II.
_The spread of influenza in 1918._
═══════════╤════════════╤═════════════╤═══════════════╤════════════════
Month. │ Date. │ Country. │ City. │ Authority
│ │ │ │ quoted.
───────────┼────────────┼─────────────┼───────────────┼────────────────
March │ │_China_ │ │McNalty,
│ │ │ │ Carnwath.
│ │Japanese Navy│ │McNalty,
│ │ │ │ Carnwath.
│ │_Japan_ │ │Jour. Am. Med.
│ │ │ │ Assn.
│ │ │Civilian │
│ │_France_ │ Population at│MacNeal.
│ │ │ Chaumont │
│ 5│_United │ │
│ │ States_ │ │
│ │Kansas │Camp Funston │Opie.
│ │Missouri │Kansas City │V. C. Vaughan.
│ │Illinois │Chicago │Frost.
│ │Ohio │Columbus │V. C. Vaughan.
│ │Michigan │Detroit │V. C. Vaughan.
│ 18│Georgia │Camp Greenleaf │V. C. Vaughan.
│ │ │Atlanta │V. C. Vaughan.
│ 28│S. Carolina │Camp Sevier │W. T. Vaughan.
│ 30│Kansas │Haskell │Public Health
│ │ │ │ Reports.
───────────┼────────────┼─────────────┼───────────────┼────────────────
│ │_United │Various points │Public Health
April │ │ States_ │ from Norfolk │ Reports.
│ │ │ to Louisiana │
│ │Mississippi │Camp Shelby │V. C. Vaughan.
│ │Georgia │Camp Hancock │Forbes and
│ │ │ │ Snyder.
│ 30│California │San Quentin │Stanley.
│ │ │ Prison │
│ │_France_ │ │Netter.
│ │ │ │Chauffard.
│ │ │ │Messary.
│ │ │ │Longcope.
│ │ │Brest (American│
│ 1│ │ Expeditionary│V. C. Vaughan.
│ │ │ Forces) │
│ │ │British │
│ │ │ Expeditionary│Carnwath.
│ │ │ Forces │
│ │ │Allied Western │Public Health
│ │ │ Front │ Reports.
│ 1│ │German Western │Gins.
│ │ │ Front │
───────────┼────────────┼─────────────┼───────────────┼────────────────
May │ │_France_ │Chaumont │Zinsser.
│ │_Scotland_ │Glasgow Dunlop,│Carnwath.
│ │ │ │Office
│ │_Spain_ │Madrid │ International
│ │ │ │ d’Hygiène
│ │ │ │ Publique.
│ │_Greece_ │Athens │Filtzos.
│ │ │ │Teissoniere,
│ │_Macedonia_ │French Army │ Beguet and
│ │ │ │ Jolly.
│ │ │Egyptian │
│ │_Egypt_ │ Expeditionary│Benjafield.
│ │ │ Forces │
│ │_Italian │ │MacNeal.
│ │ Navy_ │ │
───────────┼────────────┼─────────────┼───────────────┼────────────────
June │ │_England_ │Portsmouth │Carnwath.
│ 15│ │Birmingham │Public Health
│ │ │ │ Reports.
│ 1│_Switzerland_│Zürich │Office
│ │ │ │ International
│ │ │ │d’Hygiène
│ │ │ │ Publique.
│ 1│_Germany_ │Frankfurt, A. │Deutsche. med.
│ │ │ M. │ Wehnschr.
│ 3│ │Strasbourg │Rose.
│ │ │ (Alsace) │
│ 25│ │Bonn │Koepchen.
│ At the end │ │{Berlin │Deutsche. med.
│of the month│ │ {North & │ Wehnschr.
│ │ │ South Germany│
│ Late│_Austria_ │Vienna │Bohm.
│ 15│_Norway_ │Christiania │Public Health
│ │ │ │ Reports.
│ 15│_China_(?) │Chefoo │Public Health
│ │ │ │ Reports.
│ 16│_Brazil_ │Santos │Public Health
│ │ │ │ Reports.
│ 22│_India_ │Bombay │Public Health
│ │ │ │ Reports.
│ │_Porto Rico_ │ │Atiles.
│ │Philippine │ │Hernando
│ │ Islands │ │
│ │ │ │
───────────┼────────────┼─────────────┼───────────────┼────────────────
July │ 1│_Germany_ │Dresden │Schmorl.
│ │ │ │Office
│ │_Italy_ │ │ International
│ │ │ │ d’Hygiène
│ │ │ │ Publique.
│ 13│_Sweden_ │Malmo │
│ │ │Gothenburg │Frost and
│ │ │ │ Sydenstricker.
│ Late 27│_Netherlands_│Flushing │Public Health
│ │ │ │ Reports.
│ │_China_ │Chungking │Public Health
│ │ │ │ Reports.
│ │_India_ │Calcutta │Malone.
───────────┼────────────┼─────────────┼───────────────┼────────────────
August │ │_India_ │Punjab │Jour. Am. Med.
│ │ │ │ Assn.
│ 3│_West Indies_│Guadeloupe │Public Health
│ │ │ │ Reports.
│ │_United │Boston │Second Spread.
│ │ States_ │ │
───────────┼────────────┼─────────────┼───────────────┼────────────────
September │ │_Denmark_ │ │Frost and
│ │ │ │ Sydenstricker.
│ 11│_Republic of │ │Public Health
│ │ Salvador_ │ │ Reports.
│ 16│_Honduras_ │ │Frost and
│ │ │ │ Sydenstricker.
│ 25│_Bermuda_ │ │Frost and
│ │ │ │ Sydenstricker.
│ 30│_Jamaica_ │ │Frost and
│ │ │ │ Sydenstricker.
│ │_Mexico_ │Santa Cruz │Frost and
│ │ │ │ Sydenstricker.
│ 21│_Canada_ │Victoriaville │Frost and
│ │ │ │ Sydenstricker.
│ │ │Quebec │
│ │ │Hamilton │
│ 30│_Portugal_ │Lisbon │Public Health
│ │ │ │ Reports.
│ 28│_Morocco_ │Tangier │Frost and
│ │ │ │ Sydenstricker.
│ 14│_South Africa│ │Frost and
│ │ Union_ │ │ Sydenstricker.
│ 16│_Senegal_ │Dakar │Public Health
│ │ │ │ Reports.
│ 16│_Sierra │Freetown │Public Health
│ │ Leone_ │ │ Reports.
│ │_Korea_ │ │Schofield.
│ │_United │West and South │
│ │ States_ │ from Boston │
───────────┼────────────┼─────────────┼───────────────┼────────────────
October │ Early│_Alaska_ │ │Governor’s
│ │ │ │ Annual Report.
│ 1│_Russia_ │Archangel │Frost and
│ │ │ │ Sydenstricker.
│ │_Peru_ │Lima │Soldan.
│ │_Uruguay_ │Montevideo │Frost and
│ │ │ │ Sydenstricker.
│ 25│_Venezuela_ │ │Frost and
│ │ │ │ Sydenstricker.
│ 11│_Guatemala_ │ │Frost and
│ │ │ │ Sydenstricker.
│ 12│_Costa Rica_ │Limon │Frost and
│ │ │ │ Sydenstricker.
│ 26│_Colombia_ │Begota, │Frost and
│ │ │ Barranguilla.│ Sydenstricker.
│ │ │Cartagena, │Frost and
│ │ │ Peru. │ Sydenstricker.
│ 9│_Cuba_ │Camagney, │Frost and
│ │ │ Nuevitas │ Sydenstricker.
│ 22│_Azores_ │ │Public Health
│ │ │ │ Reports.
│ 18│_Canary │ │
│ │ Islands_ │ │
│ 19│_Madagascar_ │ │Frost and
│ │ │ │ Sydenstricker.
│ 17│_Australia_ │ │Frost and
│ │ │ │ Sydenstricker.
│ 19│_New Zealand_│ │Frost and
│ │ │ │ Sydenstricker.
│ │_Hawaii_ │Honolulu │Frost and
│ │ │ │ Sydenstricker.
───────────┼────────────┼─────────────┼───────────────┼────────────────
November │ │_British │ │Rose.
│ │ Guiana_ │ │
│ │_Dutch │Paramaribo │Frost and
│ │ Guiana_ │ │ Sydenstricker.
│ 22│_Samoa_ │Apia │Frost and
│ │ │ │ Sydenstricker.
│ │_Arabia_ │Aden │Frost and
│ │ │ │ Sydenstricker.
│ │_Iceland_ │ │Erlendsson.
───────────┼────────────┼─────────────┼───────────────┼────────────────
December │ │_Paraguay_ │Paraguay, │Frost and
│ │ │ Asuncion │ Sydenstricker.
│ │_Dominican │La Plata, │Frost and
│ 19│ Republic_ │ Puerto Plata,│ Sydenstricker.
│ │ │ Santo Domingo│
│ │_Lapland_ │ │Macklin.
│ 8│_Society │ │Frost and
│ │ Islands_ │ │ Sydenstricker.
│ 3│_Tonga │ │Frost and
│ │ Islands_ │ │ Sydenstricker.
│ │_Fiji │ │Frost and
│ │ Islands_ │ │ Sydenstricker.
───────────┴────────────┴─────────────┴───────────────┴────────────────