Eruption.—­“This appears on the third to fifth day; the fever remaining high.  During the second week all the symptoms increase and are weakening with marked delirium and coma vigil” (unconscious, delirious, but with the eyes open).  When death occurs it usually comes at the end of the second week from exhaustion.  Favorable cases terminate at this time by crisis; the prostration is extreme; but convalescence is rapid.

[Infectious diseases 201]

Fever.—­Sudden onset to even 104 to 105 degrees; steady rise for four or five days with slight morning remissions; terminating by crisis on the twelfth to fourteenth day, falling in some cases below normal; in fatal cases there is a rapid rise to 108 or 109 degrees.  The eruption appears on the abdomen on the third to fifth day.

Treatment like Typhoid.—­Mortality, twelve to twenty per cent.

Smallpox or Variola.—­Smallpox is an acute infectious disease.  It has a sudden onset with a severe period of invasion which is followed by a falling of the fever, and then the eruption comes out.  This eruption begins as a pimple, then a watery pimple (vesicle) which runs into the pus pimple (pustule) and then the crust or scab forms.  The mucous membrane in contact with the air may also be affected.  Almost all persons exposed, if not vaccinated, are almost invariably attacked.  It is very contagious.  It attacks all ages, but it is particularly fatal to young children.

Cause.—­An unknown poison in the contents of the pustules or crusts in secretion and excretion, apparently, and in the exhalations of the lungs and skin; one attack does not always confer immunity for life.  It is contagious from an early period.  Direct contact does not seem to be necessary, for it can be carried by one who does not have it.

Symptoms.—­Incubation lasts from ten to fourteen days, and is usually without symptoms.  Invasion comes suddenly with one or more chills in adults, or convulsions in children, with terrible headache, very severe pain in the back and extremities, vomiting, the temperature rising rapidly to 103 or 104 degrees.

Eruptions.—­This usually appears on the fourth day as small red papules on the forehead, along the line of the hair and on the wrists, spreading within twenty-four hours over the face, extremities, trunk and mucous membrane.

Symptoms of fever diminish with the appearance of the rash, which is most marked on the face and ripens first there.  The papules become hollowed vesicles and a clear fluid fills them on the fifth or sixth day.  They fill with pus about the eighth day, and their summits become globular, while the surrounding skin is red, swollen and painful.  The general bodily symptoms again return and the temperature rises for about twenty-four hours.  Drying of the eruption begins the tenth or eleventh day.  The pustules dry, forming crusts, while the swelling of the skin disappears and the temperature gradually falls.  The crusts fall off, leaving scars only where the true skin has been destroyed.