Membranous croup is diphtheria of the lower part of the throat (larynx), in the region of the Adam’s apple. If in a case of what appears to be ordinary croup the symptoms are not soon relieved by treatment, or if any membrane is coughed up, or if, on inspection of the throat, it is possible to see any evidence of white spots or membrane, then a physician’s services are imperative.

It is not very uncommon for patients with mild forms of diphtheria to walk about and attend to their usual duties and, if children, to go to school, and in that inviting field to spread the disease. These cases may present a white spot on one tonsil, or in other cases have what looks to be an ordinary sore throat with a simple redness of the mucous membrane. Sore throats in persons who have been in any way exposed to diphtheria, and especially sore throats in children under such circumstances, should always be subjected to microscopical examination in the way we have alluded to before, for the safety of both the patient and the public.

There is still another point perhaps not generally known and that is the fact that the germs of diphtheria may remain in the throat of a patient for weeks, and even months, after all signs in the throat have disappeared and the patient seems well. In such cases, however, the disease can still be communicated in its most severe form to others. Therefore, in all cases of diphtheria, examination of the secretion in the throat must show the absence of diphtheria germs before the patient can rightfully mix with other people.

Gargling and swabbing the throat with the (poisonous) solution of bichloride of mercury, 1 part to 10,000 parts of water (none of which must be swallowed), should be employed every three or four hours each day till the germs are no longer found in the mucus of the tonsils.