5. It generally requires the co-operation of an exciting cause, with miasmata, to produce it. This is never the case with diseases which are universally acknowledged to be contagious.
6. It is not propagated by the artificial means which propagate contagious diseases. Dr. Ffirth inoculated himself above twenty times, in different parts of his body, with the black matter discharged from the stomachs of patients in the yellow fever, and several times with the serum of the blood, and the saliva of patients ill with that disease, without being infected by them; nor was he indisposed after swallowing half an ounce of the black matter recently ejected from the stomach, nor by exposing himself to the vapour which was produced by throwing a quantity of that matter upon iron heated over a fire[26].
To the first four of these assertions there are some seeming exceptions in favour of the propagation of this fever by contagion. I shall briefly mention them, and endeavour to explain them upon other principles.
The circumstances which seem to favour the communication of the yellow fever from one person to another, by means of what has been supposed to be contagion, are as follow:
1. A patient being attended in a small, filthy, and close room. The excretions of the body, when thus accumulated, undergo an additional putrefactive process, and acquire the same properties as those putrid animal matters which are known to produce malignant fevers. I have heard of two or three instances in which a fever was produced by these means in the country, remote from the place where it originated, as well as from every external source of putrid exhalation. The plague is sometimes propagated in this way in the low and filthy huts which compose the alleys and narrow streets of Cairo, Smyrna, and Constantinople.
2. A person sleeping in the sheets, or upon a bed impregnated with the sweats or other excretions, or being exposed to the smell of the foul linen, or other clothing of persons who had the yellow fever. The disease here, as in the former case, is communicated in the same way as from any other putrid animal matters. It was once received in Philadelphia from the effluvia of a chest of unwashed clothes, which had belonged to one of our citizens who had died with it in Barbadoes; but it extended no further in a large family than to the person who opened the chest. I have heard of but two instances more of its having been propagated by these means in the United States, in which case the disease perished with the unfortunate subjects of it.
To the above insolated cases of the yellow fever being produced by the clothing of persons who had died of it, I shall oppose a fact communicated to me by Dr. Mease. While the doctor resided at the lazaretto, as inspector of sickly vessels, between May, 1794, and the same month in 1798, the clothing contained in the chests and trunks of all the seamen and others, belonging to Philadelphia, who had died of the yellow fever in the West-Indies, or on their passage home, and the linen of all the persons who had been sent from the city to the lazaretto with that disease, amounting in all to more than one hundred, were opened, exposed to the air, and washed, by the family of the steward of the hospital, and yet no one of them contracted the least indisposition from them.
I am disposed to believe the linen, or any other clothing of a person in good health that had been strongly impregnated with sweats, and afterwards suffered to putrify in a confined place, would be more apt to produce a yellow fever in a summer or autumnal month, than the linen of a person who had died of that disease, with the usual absence of a moisture on the skin. The changes which the healthy excretions by the pores undergo by putrefaction, may easily be conceived, by recollecting the offensive smell which a pocket-handkerchief acquires that has been used for two or three days to wipe away the sweat of the face and hands in warm weather[27].
3. The protraction of a yellow fever to such a period as to dispose it to assume the symptoms, and to generate the peculiar and highly volatilised exhalation from the pores of the skin which takes place in the jail fever. I am happy in finding I am not the author of this opinion. Sir John Pringle, Dr. Monro, and Dr. Hillary, speak of a contagious fever produced by the combined action of marsh and human miasmata. The first of those physicians supposes the Hungarian bilious fever, which prevailed over the continent of Europe in the seventeenth century, was sometimes propagated in this way, as well as by marsh and other putrid exhalations. Dr. Richard Pearson, in his observations upon the bilious fevers which prevailed in the neighbourhood of Birmingham, in England, in the years 1797, 1798, and 1799, has the following remark: “In its first stage, this fever did not appear to be contagious, but it evidently was so after the eleventh and fourteenth day, when the typhoid state was induced[28].” As this protracted state of bilious fever rarely occurs in our country, it has seldom been communicated in this way.
It is not peculiar, I believe, to a bilious and yellow fever, when much protracted beyond its ordinary duration, to put on the symptoms of the jail fever. The same appearances occur in the pleurisy, and in other, of what Dr. Sydenham calls intercurrent fevers, all of which I have no doubt, under certain circumstances of filth, confinement, and long duration, would produce a fever in persons who were exposed to it. This fever, if the weather were cold, would probably put on inflammatory symptoms, and be added, in our nosologies, to the class of contagious diseases.