DIAGNOSIS.
There are few diseases the prompt recognition of which is of greater
importance to the physician than variola. On the one hand, failure
to recognize the disease may subject the family of the patient and
the community at large to the danger of contagion, and thus even be
the starting-point of a widespread epidemic; on the other hand, to
pronounce a case smallpox when it is not, entails so much needless pain
and anxiety that the physician guilty of so grave an error merits the
severe condemnation which will certainly be visited upon him.
The recognition of a case of smallpox may be simple, difficult, or even
impossible, depending on the case and on the stage of the disease. In
general the disease is readily recognized when the case is typical and
the eruption has reached the vesicular or pustular stage. The diagnosis
is difficult in atypical and complicated cases. It is impossible
with any degree of positiveness in most cases in the pre-eruption
period,--the stage of invasion.
The initial symptoms of smallpox resemble the first symptoms of so
many infectious fevers that it is only through a consideration of the
prevalence of an epidemic and the opportunities for infection in a
given case that the physician may be put on his guard. It is important
in this connection to notice whether the patient has been successfully
vaccinated within a recent period. The physician who during the
prevalence of an epidemic finds an unvaccinated subject suffering
from a febrile disease of acute onset, with severe lumbar and dorsal
pains, may, in the absence of definite symptoms pointing to some other
disease, suspect smallpox; but a positive diagnosis at this stage is,
of course, impossible.
*Prodromal Rashes.*--The occurrence of the prodromal rashes, the
roseola variolosa,--a more or less diffuse scarlatiniform, morbillic,
or urticarial rash which may appear on the second day of the
fever,--has a certain diagnostic value; but this roseola occurs in
only a small percentage of the cases, and, unfortunately, sometimes
appears in other acute toxæmic conditions,--typhoid, for instance. The
scarlatiniform rash may lead to a diagnosis of scarlet fever and the
morbillic roseola be mistaken for measles; but these diseases would
be excluded by the absence of the angina and the strawberry tongue of
scarlatina in the one case and of the catarrhal symptoms of measles
in the other, aside from other considerations. The appearance of the
eruption on the second day of scarlatina is followed by a marked
defervescence, while the scarlet rash of smallpox is not accompanied
by any change in the temperature curve. The eruption in measles occurs
on the fourth day of the illness, a circumstance which alone suffices
to differentiate it from the morbilliform roseola of smallpox. The
characteristic and pathognomonic “Koplik spots” on the buccal mucous
membrane in measles are, of course, absent in smallpox. Furthermore,
these prodromal eruptions of variola are of extremely evanescent
character and usually disappear within eight or ten hours.
Of somewhat greater diagnostic value in this stage is the appearance
of small hemorrhages, or petechiæ, varying in size from a pin’s head
to a pea, in the brachial and crural triangles of Simon. This form of
prodromal eruption, however, is extremely rare, and, it may be added,
is of grave prognostic significance, as it is usually the precursor of
hemorrhagic smallpox.
*Meningitis.*--The intense headache, vertigo, delirium, and coma of
meningitis, especially meningitis of the convexity without localizing
symptoms, may be mistaken for severe prodromal symptoms of smallpox. As
a rule, pulse and respiration are slow in meningitis, while in smallpox
respiration and pulse are both markedly rapid.
*Cerebro-spinal Meningitis.*--In cerebro-spinal meningitis, in which an
erythematous or purpuric rash appears, the difficulties of diagnosis
are often such as tax the skill of the most expert clinician. It is
important to remember that the rash of cerebro-spinal meningitis
usually develops gradually or in successive crops, and that its
distribution over the cutaneous surface is irregular, while the
eruption of smallpox makes its complete appearance within the space of
a few hours and is localized chiefly on the face and extremities. The
stiffness at the back of the neck and the retraction of the head are
symptoms that do not belong to smallpox.
*Septicæmia and Pyæmia.*--Acute septicæmic and pyæmic conditions in
which there are hemorrhagic and bullous lesions in the skin sometimes
present grave difficulties in making a differential diagnosis from
smallpox. In general, however, a careful elucidation of the history of
the case will bring out some points that serve for differentiation.
It must be admitted, however, that the diagnosis between cryptogenetic
septicæmia and hemorrhagic smallpox is sometimes impossible _intra
vitam_. A case of this kind may be cited which occurred in New York
during the epidemic last year. A woman of thirty, not vaccinated
since childhood, living in a house adjoining one from which a case
of smallpox had been removed, was reported to the authorities as a
possible case of smallpox. It was the sixth day of her illness, which
had begun abruptly with headache, backache, vomiting, and fever. On
the third day of the illness there was a profuse hemorrhage from the
uterus, and thereafter metrorrhagia was almost constant. On the fourth
day a scarlatiniform eruption was noticed on the legs and abdomen.
The rash rapidly extended and was soon interspersed with hemorrhagic
points. When seen on the evening of the sixth day the patient was
semi-comatose. The skin was literally covered with a dusky scarlet rash
in which were noted countless hemorrhagic macules, from a pin-point
to a bean in size. The conjunctivæ bulbi were chemotic, the tongue
was swollen, and the fauces were deeply congested. The post-mortem
examination made the following morning, six hours after death, revealed
a septic endometritis, and streptococci were cultivated from the blood
and the peritoneal serum.
*Grippe.*--An attack of grippe may simulate the early symptoms of
smallpox very closely. The onset may be sudden, the muscular pains
severe, the pyrexia decided, the general prostration as marked as
in smallpox. In grippe, however, the muscular pains are, as a rule,
more general than in smallpox, there is rarely profuse sweating, and
symptoms referable to the respiratory tract soon develop, if indeed
they are not present from the beginning.
*Rheumatism.*--The severe lumbar and sacral pains of smallpox have
been mistaken for rheumatism, but such an error can be made only where
the use of the clinical thermometer is unknown. A febrile movement
in lumbago is absent or but slight, while in smallpox the pyrexia is
usually pronounced.
*Typhoid and Typhus.*--Typhoid and typhus fevers have at times been
confounded with smallpox. But errors of this kind can be made only
where the history of the case is completely ignored. In typhus, it is
true, the eruption, petechial and almost papular in character, may
suggest hemorrhagic smallpox; but the eruption of typhus rarely appears
before the fourth or fifth day of the illness and is located chiefly on
the trunk, sparing the face. The rash of malignant smallpox develops
usually on the third or even the second day of the illness and is not
limited to the trunk.
Upon the appearance of the rash in a typical case of smallpox the
febrile diseases with which it is most frequently confounded are
measles and varicella. It is interesting to note that until the time of
Sydenham, in the latter part of the seventeenth century, measles and
smallpox were regarded as manifestations of the same disease, and that
the Vienna school of dermatologists, even to this day, insists on the
etiological unity of variola and varicella.
*Measles.*--As a matter of fact the early papular eruption of measles
bears a considerable resemblance to the first stage of the eruption of
smallpox. In both the eruption is noted first in the face. In smallpox,
however, the papules have a firm, “shotty” feeling on palpation, while
in measles they are smooth and velvety to the touch. In measles the
eruption, viewed at a little distance, seems to present a distinctly
corymbose or crescentic grouping, an arrangement which is absent in
smallpox. The eruption of smallpox appears at the end of the third
day, that of measles on the fourth day. The temperature in smallpox
undergoes a rapid defervescence upon the appearance of the rash,
while in measles it continues to rise after the eruption appears.
The pronounced pain in the back is absent in measles, while the very
marked catarrhal symptoms, coryza, conjunctivitis, etc., are lacking in
smallpox. The subsequent course of the eruption will leave no room for
doubt, since within twenty-four hours the papules of smallpox will have
developed into characteristic vesicles.
*Varicella.*--In varicella the stage of invasion is usually much
shorter than in smallpox, the prostration less marked, and the lumbar
pains of the latter disease are absent. The eruption in varicella comes
out in successive crops and runs a shorter course, so that lesions in
various stages of development may be seen side by side. The temperature
does not necessarily fall on the appearance of the eruption, and there
may be a more or less marked rise with each fresh crop of vesicles, the
temperature curve presenting thus a remittent character. The eruption
itself presents marked differences in the character and the course of
the individual lesions, as well as in their distribution. The clear
vesicles shoot up from the surface, as it were, without warning; or
there may be for a brief period only a circumscribed erythema like
that which usually precedes the appearance of an urticarial wheal.
The vesicles of varicella have usually a somewhat obtusely conical
shape, while those of smallpox are distinctly hemispherical. The
characteristic umbilication of the smallpox vesicle is wanting in
varicella. It is true the varicella vesicle often shows a depression
at its apex; but this false umbilication, as it is called, is due to
the rupture of the vesicle and the escape of some of its fluid or to
a partial drying of its watery contents, and occurs only after the
vesicle has existed for some time. The vesicle of varicella appears
much more superficial in its seat, and its roof is much thinner, so
that it ruptures readily. Very moderate pressure with the finger
suffices to break it. When ruptured in this way the vesicle usually
collapses completely, contrasting in this respect with the smallpox
vesicle, from which, owing to the multilocular character of the lesion,
all the fluid does not escape.
In varicella the distribution of the lesions over the surface is far
more erratic than in smallpox. The very decided tendency to grouping
of lesions upon the face and about the wrists so characteristic of
smallpox does not occur in varicella, in which the vesicles may appear
even more extensively on the trunk than upon the face. In varicella
the palms and the soles, except in infants, are almost never affected;
while in smallpox these regions are practically never exempt. It is
true that in the extraordinarily mild cases of smallpox, such as have
constituted the majority of cases during the past two years throughout
the West, lesions may or may not be present on the palms and soles; but
in the severe and moderately severe cases, such as have characterized
the recent epidemic in New York, the soles and especially the palms
have practically without exception shown the lesions. The localization
of smallpox lesions on the palms and soles deserves far more emphasis
than is generally accorded it in the textbooks, many of which even
fail to mention it all. It may be put down as a safe rule that a
case showing an extensive eruption of vesicles or pustules, however
suspicious in other respects, is not smallpox if the palms and soles
are free.
*Acne.*--Among the skin diseases proper there are a few whose
appearance upon hasty examination may occasion some confusion with
smallpox. Acne pustulosa presents only a superficial resemblance to
variola, but in cases where it is accidentally associated with an acute
febrile disease, like grippe, for instance, it may give rise to some
diagnostic difficulty. In these cases, however, inquiry will develop
the fact that the acne lesions have been present before the inception
of the febrile disease; and the presence of comedos, the limitation of
the lesions to the face, chest, and back, together with the absence of
any lesions on the palms and soles, will serve to exclude smallpox.
*Impetigo Contagiosa.*--In impetigo contagiosa there might under
similar circumstances be a momentary doubt as to the nature of the
illness. Impetigo lesions have no typical distribution on the surface,
the mucous membranes are always exempt; the vesicle itself is extremely
superficial, ruptures very readily, and is at once replaced by a crust,
so that lesions in various stages, vesicles, pustules, and crusts may
always be seen at the same time.
*Zoster.*--Zoster is, as a rule, readily distinguished by the definite
grouping of the lesions in the tract supplied by one or more nerves,
its asymmetrical distribution, and the more or less severe neuralgic
pain that precedes or accompanies the eruption. It must be remembered,
however, that in zoster, in addition to the typical grouped lesions,
there are occasionally seen a few isolated vesico-pustules scattered
promiscuously over the entire surface; and the difficulty of diagnosis
may be increased by the occurrence of a moderate temperature movement.
In these cases, to which attention was first called by Teneson, the
history of the case, the presence of characteristic herpetic groups,
and the evolution and course of the individual lesions will suffice to
clear the diagnosis.
*Drug Eruptions.*--The ingestion of bromides, iodides, and quinine
is sometimes followed by an eruption which may create some confusion
in diagnosis. In general the drug eruptions may be distinguished by
the absence of fever and of the subjective symptoms of smallpox. The
bromide and the iodide acne never occur on the palms and soles, where
there are no sebaceous glands, and the lesions lack the evolution
and course of the variolous eruption. The erythematous and purpuric
eruption of quinine may be confused with the hemorrhagic form of
smallpox; but here, too, the history of the course of the illness and
the absence of fever will obviate the difficulty.
*Syphilis.*--Of all the diseases of the skin it is the pustular
syphilide which most resembles the lesions of smallpox. Dermatologists
and experts in variola are agreed that the pustular syphilide may be
absolutely indistinguishable from smallpox so far as the appearance and
distribution of the lesions is concerned. Furthermore, the pustular
syphilide is frequently accompanied by a decided febrile movement. The
differential diagnosis can be made in these cases only by the closest
inquiry into the history of the case and by careful observation of
the course of the disease. The characteristic history of an acute
illness of short duration followed by a remission on the appearance
of the eruption will of course be wanting in syphilis. The syphilitic
eruption is more sluggish in its evolution as well as in the course of
its subsequent changes; and though there may be lesions of syphilis on
the mucous membrane of the mouth, they will lack the characteristic
appearance of the vesicles and pustules of smallpox in this region.
The palms and soles are not apt to show any lesions in this form of
syphilis; and finally some other forms of syphilitic manifestation are
very often present in this polymorphic disease to give the clue to the
real nature of the eruption.
In conclusion, the fact should be emphasized that there are cases of
smallpox of so mild a character, with general symptoms so slight and
eruption so sparse and ill-defined, as to make a positive diagnosis
extremely difficult. It is a good plan to employ vaccination in such
cases as a test. Within three or four days the experienced observer
will be able to determine whether the vaccination is successful or
not; a negative result will of course have but a moderate value, but
a positive result will serve to definitely exclude the diagnosis of
smallpox. In all cases of doubt, whether before or after the eruption
has appeared, the physician owes it to himself not less than to the
patient and the community to frankly explain to the patient or his
family the difficulty in arriving at a diagnosis, and to express his
suspicions that the case may be one of smallpox. It need hardly be said
that such a case should be as strictly isolated as if the diagnosis of
smallpox were already established.