Influenza—The Sphinx of Diseases - 1919

Interior of Red Cross House at U.S. General Hospital #16, New Haven, Conn. During the Influenza Epidemic. The Beds Are Isolated by Curtains. Photograph by American Red Cross circa 1918-1919. Library of Congress # 2017668663. GGA Image ID # 1501d39d58

By Wade W. Oliver, M.D., Professor of Bacteriology, The Long Island College Hospital, Brooklyn.

WHEN we speak of the cause of a disease, we are guilty of an error. Any given disease has many causes. For purposes of convenience and exactitude, the causes of a disease are divided into two classes (1) the exciting cause and (2) contributing causes.

The contributing causes of influenza include such factors as overcrowding, universality of travel, promiscuous coughing and sneezing of individuals suffering from the disease, etc. The exciting cause of influenza, i. e., the particular germ responsible for setting up the infection, is not known.

It is a curious and suggestive fact that, in regard to exact knowledge of the exciting cause of a number of our most common diseases, we are almost as woefully in the dark as was Hippocrates, "the Father of Medicine!"

The list of diseases of doubtful or unknown causation includes such common maladies as small-pox, mumps, whooping cough, measles, scarlet fever, and influenza.

Leaving out of consideration, for the moment, the recent world-wide epidemic of influenza, whose toll of death so sardonically abetted the ravages of war (in this country alone, estimates place the number of deaths from influenza during the past three months at from one quarter of a million to three hundred thousand), we find that there are few ailments which are responsible for so general a physical, mental, and economic impairment as are "common colds."

Universal attention has been attracted to this malady because of its apparent recent outbreak in epidemic and pandemic form, erroneously termed "Spanish influenza."

Confusion has been worse confounded by loose statements in both the "lay" and "medical" press that "Spanish influenza" is really bubonic plague, or what is commonly spoken of as "the black death."

In the rapidity of its spread, in its high mortality, and in certain of its manifestations in the body, the disease has somewhat simulated, in certain respects, the pulmonary form of plague, that dread scourge of the tropics.

But just as one, or even several swallows, do not make a summer, so do certain similarities fail to establish the identity of two distinct diseases.

In 1892 Dr. R. Pfeiffer, of Berlin, described a germ lower air passages, which he believed to be the cause of influenza and, in honor of his discovery, the micro-organism has come to be known as "Pfeiffer's Bacillus."

It is a tiny rod, one of the smallest known disease-producing bacteria, averaging from 0.5 micron to 1.5 microns in length and 0.3 micron in thickness (1 micron=approximately 1/25000 of an inch.

In 31 cases suffering from epidemic influenza, he found this germ in the sputum coughed up from the Independently, and in the same year, Canon claimed to have found the same germ in the blood of influenza patients.

Pfeiffer based his original argument that the germ discovered by him was the exciting cause of influenza upon the following grounds:

(1) The influenza bacillus was found in the pus-laden sputum coughed up from the lower air passages (bronchi) in all uncomplicated cases of influenza.

(2) He claimed to have found this germ only in cases of influenza.

(3) He found the bacilli corresponded with the course of the disease and that when the purulent (pus-containing) secretion from the bronchi ceased, the micro-organisms disappeared.

(4) He claimed to have simulated, in essential details, the disease in rabbits and apes by injecting into the veins of these animals a pure culture of living influenza bacilli suspended in bouillon.

Weichselbaum (1892), Huber (1893), Kruse (1894), Richter (1894), Baumler (1894), Borchardt (1894), rather quickly confirmed Pfeiffer's work as regards the presence of the influenza bacillus in the sputum of patients suffering from epidemic influenza, findings which have been reported by many competent bacteriologists since that time.

The second and third of Pfeiffer's contentions, viz., that the bacillus is found only in cases of influenza and that when the secretions cease, the bacilli disappear, have been somewhat discredited by the work of subsequent investigators.

In the bronchial secretions of persons convalescent from the disease, the bacillus of Pfeifier not infrequently persists for long periods of time and even may occur in the throats of normal, healthy individuals for years.

His fourth contention, i. e., that in rabbits, by intravenous injection of pure culture of B. influenza, influenza-like symptoms were set up, is not generally agreed to by more modern bacteriologists, nor is his statement that by rubbing a pure culture of the bacillus within the nose of monkeys he was able to set up influenza-like symptoms in these animals.

When to this is added the fact that, even as early as 1892, sputa were reported from influenza patients, during the course of rather widespread outbreaks of influenza in Europe following the great pandemic of 1890-92, in which persistent search failed to show the presence of Pfeiffer's bacillus, although other germs, such as the streptococcus, were found almost if not quite as constantly in the sputum of influenza patients, germs which had as much or as little scientific license for being considered the cause of the disease as did the bacillus championed by Pfeiffer, we are given a curiously pertinent insight into the not infrequent orthodoxy of science.

Truly, we, in whose eyes, science has almost the stature of a god, must walk a little more humbly within "that frail and ill-assured edifice of knowledge" wherein we dwell.

Until the past year, the Pfeiffer bacillus has occupied an almost unassailable position in the halls of Bacteriology and only now is the conception that this germ is the true cause of influenza being shaken from its high altar.

Fuel for the fires of skepticism is added in the form of such experiments as those referred to in an editorial in the issue of the SCIENTIFIC AMERICAN of February 1st, very recently performed by the United States Public Health Service and the United States Navy (Some Interesting Though Unsuccessful Attempts to Transmit Influenza Experimentally, Pub. Health Rep., 34:33, Jan. 10th, 1919).

In the series of tests made at Boston, 68 men from the naval detention camp at Deer Island were inoculated with pure cultures of the influenza bacillus, with secretions from the nose and throats of patients in the early stages of influenza and with the blood of individuals afflicted with influenza.

Living influenza bacilli, suspended in sterile salt solution, were sprayed or swabbed into the noses or throats of these volunteers, as were both filtered and unfiltered secretions from the air passages of patients in the active stages of influenza.

In addition, ten healthy men deliberately leaned over beds of ten selected influenza patients and allowed these patients to cough directly into their faces. Not one of the 68 volunteers, developed influenza.

Certain French investigators, particularly Nicolle and Le Bailly, and Dugarric de la Reviere, have within the past few months reported experiments which lead them to believe that the primary cause of influenza is a filterable virus. (By a filterable virus is meant micro-organisms which are so tiny that they will pass special filters through which even the smallest known bacteria will not go).

These experiments, which have been confirmed by certain investigators and denied by others, still await scientific acceptance. Even though they be accepted, they confess to an ignorance concerning the real nature of the living agent primarily responsible for the disease.

If, then, we are forced to conclude that it has not been satisfactorily proved that the Pfeiffer bacillus is the cause of influenza, and if there is considerable room for doubting that the disease is set up by a filterable virus, what is the present status of our knowledge?

In an editorial in a recent number of one of our most widely read medical journals (Journal American Medical Assn., Vol. 71, No. 26, Dec. 28th, 1918, p. 2154), the case is succinctly stated:

"The primary cause of influenza, in so far as our knowledge at the present time goes, is an unknown agent that prepares the way for secondary invasions of the respiratory tract."

To this confession, must be added another, even more basic in its significance. Again we quote, this time from The Report of a Special Committee of the American Public Health Association, on Influenza:

"While the prevailing disease is generally known as influenza, and while it may be so referred to in this statement, it has not yet been satisfactorily established that it is the identical disease heretofore known by that name, nor has it been definitely established that all preceding outbreaks of the disease styled at the time "influenza' have been outbreaks of one and the same malady. There is no known laboratory method by which an attack of influenza can be differentiated from an ordinary cold or bronchitis or other inflammation of the mucous membrane."

To the intellectually honest man, it is a wholesome corrective to be compelled to say rather frequently: "I do not know!"

Oliver Wendell Holmes once stated (Medical Essays, Houghton Mifflin, 1890, p. 11): "The best part of our knowledge is that which teaches us where knowledge leaves off and ignorance begins. Nothing more clearly separates a vulgar from a superior mind than the confusion in the first between the little that it truly knows, I on the one hand, and what it half knows. and what it thinks it knows, on the other."

Wade W. Oliver, M.D., "Influenza—The Sphinx of Diseases," in the Scientific American: The Weekly Journal of Practical Information, New York: Scientific American Publishing Company, Vol. CXX, No. 9, 1 March 1919, p. 200, 212-213.