SERUM DISEASE The injection of the serum causes according to its quantity a smaller or larger swelling, which is more slowly absorbed than an equal quantity of physiological salt solution. But as much as 200 c.c. are perfectly absorbed within twenty-four to forty-eight hours. Aside from a slight discomfort at the site of injection no changes are apparent during the first few days.
The small quantities of diphtheria serum employed to-day produce clinical symptoms in only 5 per cent. of cases, although in every case there are biologic changes going on in the organism, of which we shall speak in connection with reinjection.
In typical cases the symptoms of serum disease begin to appear eight to twelve days after injection.
There may be slight prodromal symptoms, as transitory redness, sensitiveness of the skin of vasomotor origin. A more constant and early symptom is the swelling and tenderness of the regional lymph-glands continuing throughout the disease without ever going on to suppuration. Usually the first symptom we notice is a breaking out of urticaria, origi nating at the site of injection where it sometimes remains localized.
The eruption, accompanied by intense itching, varies greatly in size and shape, changing from disseminated small wheals surrounded by a red border to large urticaria infiltrations as large as the palm of the hand, and tend to spread quite rapidly over the entire body. Each individual wheal is of short duration, but for a number of days there appear successive crops.
As a result the face is often greatly swollen, general may be present, not sufficiently marked to be apparent, although its presence may be proved by weighing the patient, when an increase of several pounds may be found. The oedema is not of nephritic nature, for only ex ceptionally do we find albuminuria, never nephritic elements in the urine.
Inflamed areas seem predisposed to (edema, at. least cedema of the larynx after it has disappeared is sometimes seen to recur at the time of the urticaria eruption and may produce symptoms of laryngeal stenosis (subglottie (edema of Mya).
The knowledge of this fact is of great practical importance, because otherwise one is inclined to regard the reappearance of the stenosis as a recurrence of the croupous process and to again inject serum which would only aggravate the condition. Intubation, however, is not. con traindicated. The prognosis is good; with the disappearance of the serum disease the laryngeal stenosis subsides.
The eruption of urticaria is accompanied by a moderate rise in temperature, only exceptionally is a high temperature observed. The type of the temperature is remittent ; the exanthem may, however, occur without temperature, although more frequently the opposite is the case, where we notice a rise of temperature without other symptoms of serum disease (formes frustes of Lehndorff).
The mild eases lasting generally but a few days are almost entirely free from constitutional disturbances. The patients feel ill only when the joint pains appear, which are supposed to be due to changes in the synovia analogous to the exanthem.
More severe constitutional disturbances occur in cases where the serum disease is of long duration following the use of large doses (50 to 400 c.c.) of horse serum. In these eases we may also notice rarer forms of exanthems following one another, the most important being the one resembling measles and the erytheme margine aberrant (Marfan) resem bling the erythema multiforme of the other types of the exanthem, only the erythema resembling scarlatina is of some importance. It is really quite rare; most cases of supposed scarlatinoid serum exant hem are cases of genuine scarlatina. The diagnosis should therefore be made cautiously.
The diagnosis of scarlatina is positive in the presence of marked redness of the mucous membranes of the mouth and throat, for the mucous membranes in these places are never involved in serum disease. The con junctiva, the bronchial and intestinal mucous membranes may in rare eases be involved, a slight catarrhal condition being the result.