By OSKAR KLOTZ, M. D., C. M.
The discussion to be entered into in this report will be limited to an
experience dealing with epidemic influenza as it was met with in the
emergency Military Hospital in Pittsburgh. We shall largely confine our
attention to the observations which came directly under our supervision,
and in as much as this investigation was continued during the epidemic
as it swept over this district, the intensive study was limited to a
time period of about five weeks. During this period much material was
collected, which since then, has taken us a considerable time to
analyze. We have thought it more valuable to restrict our discussion to
this material in that it illustrates the pathological lesions as they
occurred during the acute stage of the disease. We have not entered upon
a discussion of the sequelæ or the chronic lesions which are not
uncommonly found following in the wake of an acute epidemic nor do we
deal with the lesions arising in cases of sporadic influenza, such as
are always with us. As is so well illustrated in the literature, there
is probably no disease which has so many late complications and sequelæ
as influenza. The investigations upon the protean lesions have been
fully reported in numerous papers during the intervals between
epidemics. A comprehensive bibliography upon influenza will be found at
the end of the extensive report by Leichtenstern (1905). There is very
much less accurate information available upon the actual lesions present
during the acute disease when present in epidemic or pandemic form, than
upon the many clinical complications in various systems and organs. In
fact, our knowledge of the pathology of influenza lies more largely in
the field of associated lesions such as the late events in the bronchi,
the sinuses of the head, abscesses, meningitis and other conditions,
rather to be viewed as complications than as portions of the disease.
There are relatively few thorough pathological analyses of the influenza
lesions as they are found in the acute epidemic disease.
A fair literature has already appeared upon epidemic influenza from the
many countries and regions over which the present pandemic (1918) has
swept. These reports by various authors are offered from different
viewpoints, some investigators being impressed with certain features
which they bring into marked prominence in their reports. It thus
happens that up to the present there is a decided lack of uniformity in
the opinions expressed upon different phases of the subject. The nature
of the pathology of the past epidemic has given rise to many expressions
of opinion as well as dogmatic statements, which are found to differ
from those of others. It seems to us that this apparent confusion arises
partly through the somewhat different characteristics of the disease as
it has made its appearance in different centers. We hear it repeatedly
stated that the types found in different military camps and urban
communities were quite unlike those of other regions. It is evident that
such differences in the clinical course actually did exist and that the
epidemic though having a common foundation upon which the disease
process was built differed in what might be looked upon as symbiotic
complications during the early and acute stages. Differences in the
nature of the findings in various communities also probably lay in the
fact that the bacterial flora associated with the causative agent of
influenza was quite different in different regions. We mention this here
so that a full appreciation will be obtained for the differences in the
pathological characters of the disease as they are found in one region
or another. We appreciate, of course, that if the concomitant bacterial
flora associated with the underlying cause of influenza, differs in
different regions, so, too, will the bodily reactions differ within
certain degrees. We are becoming more familiar with different types of
bacteria, and the resulting inflammatory reaction which is often unique
or at least particular, and that not uncommonly the nature of the
inflammatory process suggests the type of bacterium involved. This
argument, of course, must not be driven too far, for we well know that
the same micro-organisms under different conditions can cause types of
inflammatory reactions wholly divergent.
In as much as our observations are confined to a particular group of
cases and the study of these was undertaken during the five weeks of the
acute epidemic, these results are not to be compared with the collected
statistics on influenza as they shall be made over a period beginning
with the onset of the epidemic and ending with the last vestiges
remaining after months or it may be years of time. Our observations are
to be considered only in the light of the events taking place during the
height of an epidemic wave. In as much as influenza presents itself
during an epidemic in different forms, we shall again mainly limit the
report upon our investigations of those cases having respiratory
lesions. Our acute observations were made upon the tissues of those who
had died of this disease. It is impossible, or nearly so, to fully study
the tissues of those with lesser lesions and who recover. Hence, if we
divide the influenza cases into those (1) without pulmonary lesions and
(2) those with pulmonary lesions, we must state that all of our cases
coming to autopsy fall in the second group. It is true that one of these
having pulmonary lesions was not brought to his fatal termination by
them but by a septicæmia arising in the middle ear. He had distinct
lesions in his lungs. In other words, our autopsy material represents
epidemic influenza in which the lung was definitely involved in an
inflammatory state. In all but one of these the pulmonary lesion was the
cause of death.
No doubt, if opportunity had presented itself to follow a large epidemic
through months of its progress, during which late complications in
various portions of the body would make their appearance, our analysis
would give a different picture and the pulmonary factor for the fatal
termination would not be in such prominence.
Of the first group, those cases of epidemic influenza not showing
pulmonary lesions, we will have very little to say, in as much as the
pathological investigations of them is impossible, or nearly so, during
the height of the disease.
Such cases apparently do not die at this period. I am willing to admit
that individuals without pulmonary involvement may succumb, but I
question whether their death has been due to the result of the
influenzal lesions, be it in nose, pharynx, larynx or trachea, or be it
in the intestine, but rather that the fatal termination occurred later
in the course of this complex disease, when distant vital organs became
involved or incapacitated in a toxemia or secondary bacterial invasion.
We must clearly distinguish these cases from the clear-cut ones of
epidemic influenza, looking upon the new circumstances as complications
aside from the original disease. Such, for example, is the case we have
mentioned where a fatal streptococcus bacteriæmia followed in the wake
of an otitis media. In our experience we have not had a fatal case of
the acute epidemic disease in which the lung was not involved.
In types of epidemic disease such as we have just had, where the
epidemic wave has passed over in a period of four or five weeks, there
is always much to be regretted which has been left undone. We tried as
far as possible to gain all the information available at the time of
collecting our materials and of laying aside such of the work which
could be accomplished at a subsequent date. The materials were collected
from divergent sources in the cadaver, and the more perishable
substances were analyzed immediately. During the period of the epidemic
32 autopsies were performed and as much use as possible was made of each
for a thorough comprehension of the lesions.
_Materials_
During the period of our work 639 patients were admitted to the hospital
suffering from clinical influenza. The cases varied in type from the
very mild to the extremely ill. The majority of the cases were of the
type of “three-day fever.” Clinically 81 cases developed pneumonia, and
of these, 35 died. It would, of course, be impossible to say how many
other individuals had a pulmonary involvement which could not be
recognized clinically. In fact, some of the cases which did come to
autopsy were only recognized as having a pulmonary involvement when the
lungs were examined outside of the body. The physicians freely admitted
that the physical signs were quite unusual and unlike those of the
ordinary forms of pneumonia. In fact, except for the fact that we were
living in the midst of an epidemic of respiratory infections, there was
nothing to make the clinician suspect that many of these cases had a
pulmonary involvement. Obviously, when the recognized signs of different
types of pneumonia made their appearance, the clinician did not fail to
make proper interpretation of the lung involvement. This, as we shall
discuss later, is an event superadded to a lung condition which
pathologically must be recognized as pneumonia (inflammation) and which
differs so decidedly from what we know of as croupous or lobar
pneumonia, as well as ordinary broncho-pneumonia that it would be
incorrect to include them under this heading, although the distribution
of the lesion may have lobar, bronchial or lobular characters.