The epidemic of influenza, prevalent in Europe during the Great War, was
watched with interest everywhere, not only because of its military
importance, but also because of the danger of its spreading to other
continents. The prediction that this would occur, made months before its
realization, was verified on an even larger scale than had been
anticipated, for in the autumn of 1918, this acute respiratory infection
passed over the United States like a huge wave, taking a tremendous toll
in human lives; later smaller waves followed leaving in their wake
corresponding degrees of devastation. The first cases of the disease
appeared on the New England coast, and New Haven was among the cities to
be early invaded, though here the epidemic was somewhat less severe than
in other cities along the Atlantic Seaboard.
Forewarned and alert to the danger, medical men spared no effort in
studying the disease; as a result, no malady, perhaps, has ever been
investigated so intensively and from so many different points of attack
in an equal length of time. Proof of this appears in the abundant
literature issuing from every quarter. Among the various contributions
to this subject, many include the anatomical changes associated with the
disease. In general, however, these are brief; and although they serve
their special purpose well, they have not been elaborated sufficiently
to close the chapter.
During a period of about three months beginning with September 18, 1918,
while the epidemic raged and waned in New Haven, there were
approximately eleven hundred cases of the disease admitted to the New
Haven Hospital. As is so often true, only the more critically ill sought
hospital care, and few, if any, patients affected by other respiratory
infections are included in these statistics. The mortality here, as
elsewhere, was very high; of two hundred eighty (280) cases that ended
fatally, eighty-two (82) were investigated at the post-mortem table. An
attempt was made to make the studies very complete, and this was favored
since the headquarters of the Yale Army Laboratory School, under the
command of Colonel Charles F. Craig, were located at the Brady
Laboratory where a large number of men were being instructed in
Pathology and Bacteriology. It was also fortunate that competent
illustrators were available who made a splendid series of water-colors
and drawings of the characteristic lesions, both gross and microscopic.
The number of autopsied cases at the New Haven Hospital was augmented by
a series of acute fatalities from the same disease at the United States
General Hospital No. 16, at Allingtown, West Haven, where the anatomical
studies were carried on by the same group of men. The latter autopsies
offered nothing new, but served to corroborate the conclusions reached
at the New Haven Hospital.
The majority of the fatalities occurred in the acute stage of the
disease, the anatomical aspects of which have been elaborated more or
less completely.[1] Other cases survived for a longer period and in
these, anatomical changes existed, which, as will appear later, were
prognosticated from the acute lesions. Moreover, these findings
suggested that certain progressive anatomical changes occur even when
the disease runs a much less severe clinical course; for example, in
cases where respiratory symptoms persist for a long period before they
are brought to a fatal conclusion.
History, too, suggests such a chain of events; namely, in the record of
the delayed crop of respiratory disorders that followed the harvest of
the epidemic of ’90.
Previous studies of experimental pneumonia in normal and aplastic
animals by one of the authors (160) give a background for the
interpretation of the histology of some phases of this disease, but more
important are the studies of the respiratory inflammatory processes
initiated by the inhalation of toxic gases. This subject, introduced
into human Pathology with the use of poisonous gases in modern warfare,
necessitated elaborate investigations which have just been concluded
(159).
The pathology produced by the inhalation of these poisonous vapors is
analogous to that found in influenzal pneumonia. This is said with a
full comprehension of the criticism that may follow such a statement,
and with the knowledge that a similar analogy has been drawn between
influenzal and plague pneumonia (Symmers, 141). It is, however, a
criticism that is welcomed and which will be met in the body of the
paper.
For the reasons just cited, it has seemed desirable to contribute to the
Pathology of various phases of influenzal pneumonia and to attempt to
correlate this with other types of acute respiratory inflammation, in
the hope that the prognostications which suggest themselves may be of
aid in the prophylaxis and possibly in the treatment of the more
insidious and progressive pulmonary changes that may follow this
disease.
A large part of the text is devoted to a description of the gross and
more minute pathology of the respiratory tract associated with influenza
and its complications, both in the acute and in the subacute or chronic
stages. Incidental lesions of less importance in other portions of the
body that have occurred in these cases are presented briefly, and
emphasis is placed upon a number of special subjects. The order of
discussion will be as follows:—