contagium

Little has been said either of the nature of the contagium or of the conditions that modify its activity.

And the facts already mentioned may be recalled, which show that the contagium cannot be a light and subtle substance, since, as has been stated, the immediate attendants upon cholera patients are not as apt as might be expected, on that hypothesis, to contract the disease, while washerwomen inhaling, and probably swallowing, the moist fumes from cholera fomites much more frequently do so; that fomites saturated with the dried discharges are very infectious; and that water is the principal vehicle by which cholera-germs are carried into the stomach.

A freezing temperature ordinarily destroys the contagium of yellow fever.

Most observers hold that the contagium is not in the blood, but that it resides in the secretions of the respiratory passages, and is most virulent during that stage of the disease when the secretion is abundant.

I do not, however, feel entirely satisfied in adopting the view that the contagium of whooping cough resides alone in the mucous membranes of the air-passages.2 Children have been known to be born with the disease, the mother having suffered from it some time previous to confinement.