CONTAGIOUSNESS OF DISEASES.

New Zealand Graphic, Volume IX, Issue 18, 30 April 1892, Page 460

CONTAGIOUSNESS OF DISEASES.

Among the practical questions connected with the subject of contagious diseases is one which relates to the length of the period of special exposure. The Medical and Surgical Journal says that the contagiousness of measles, mumps, and whooping-cough disappears with the patient’s recovery ; that there is probably no danger of his conveying the disease to others for about a week after he himself was exposed to it—that is to say, during the so-called period of incubation ; and that the contagiousness of measles does not extend beyond a fortnight.

Some authorities affirm that the contagiousness of whoop-ing-cough ceases after six weeks, however long the coughing may continue ; others think it prudent to isolate the patient until the paroxysms are over. In scarlet fever and diphtheria the period of incubation is brief, a few days only ; and during this period there is no contagion. It is very important to know that in scarlet fever the period of greatest danger is after the disappearance of the fever, the period of desquamation or peeling. From ignorance of this fact many lives have been lost. Persons have gone into society before the peeling was completed, and almost of course have communicated the disease. The fact is that every particle of the scales contains thousands of microbes.

A lady who was recovering from scarlet fever wrote a letter to a distant friend. As she wrote she blew from the paper the ‘dust’ which peeled from her hand. The letter conveyed the disease to the friend and her little daughter, and the daughter died. A servant nursed a scarlet fever patient, and on leaving the place put her clothing into a trunk. A year afterwards she unpacked the trunk, and a little girl who stood by took the disease.

In diphtheria the virus resides in the false membrane, and for that reason is less likely to be carried to a distance ; but the particles long retain their power of infection. The contagiousness of consumption lies in the patient’s expectorations and discharges. If these are carefully received in a disinfecting fluid, there is almost no danger to attendants and friends.