Ordinarily, man is so susceptible to plague that there is no reaction at the site of inoculation but in these mild cases there is an inflammatory reaction resulting in a vesicle or pustule, which may teem with plague bacilli. In such cases it is extremely important to search for such primary vesicles and examine for plague bacilli. It is usually stated that only about 5% of cases of bubonic plague show these vesicles.
Pestis Major.—Pestis major can certainly be divided clinically and epidemiologically into two types, pestis bubonica, or bubonic plague, which is the common type of plague, and pestis pneumonica, or pneumonic plague, the contagiousness of which is extreme and the mortality practically 100%.
Both of these types of plague tend finally to show an invasion of the blood stream with plague bacilli, the case then becoming one of septicaemic plague. Many authors, however, recognize an overwhelming plague septicaemia in which the manifestations of buboes or pneumonia are absent and such cases are designated septicaemic plague, or pestis siderans.
In all forms of pestis major there stand out the characteristics of rather sudden onset, rigors or chilly sensations, rapidly rising but irregular fever, marked giddiness, great prostration, the mental state and speech of an intoxicated person and extreme weakness of the heart with a rapid weak pulse.
Typhus fever alone shows an equal degree of early mental hebetude, so that it is stated that Clot Bey, who had seen much plague in Egypt, when elsewhere shown cases of typhus with parotid involvement, remarked “In Egypt one would call such cases plague.”
A Typical Case of Bubonic Plague.—After a period of incubation of from three to seven days the disease may set in quite abruptly, or after a prodromal stage, in which malaise, giddiness, mental hebetude and pains in the back and limbs may be present. With the onset of the attack the effects of the toxaemia upon the nervous system are the most striking. The patient has a pale, drawn, anxious countenance, with injection of the conjunctivae toward the inner canthus.
The speech is thick and difficult, the gait is staggering, so that, with the stupid mental state and tendency to wander aimlessly about, one has the symptom-complex of an alcoholic intoxication. In some cases a delirious tendency may be marked, especially as the disease develops. After a few hours, or within a day, the fever begins to rise rapidly and is often associated with shivering attacks. The face now becomes hot and flushed, the conjunctivae markedly injected, the pupils dilated, and the eyes rather staring. The temperature is as a rule from 102° to 104°F., occasionally higher, with a tendency to rather marked remissions and, on the whole, of great irregularity of the fever curve. The pulse is rapid and shows early indications of the extreme toxic effect exercised upon the heart. Cardiac weakness is a marked feature of plague.
The urinary secretion is diminished but there is rarely more than a slight amount of albumin.
The Pathognomonic Bubo.—About the second or third day the development of an extremely painful bubo practically gives the diagnosis.
About 70% of these buboes are of the inguinal region, the femoral glands being more frequently invaded than those above Poupart’s ligament. The axillary glands are involved in about 20% and the submaxillary and cervical ones in from 5 to 10% of cases.