It has been common with authors to divide the symptoms of this fever into three different stages. The order I have pursued in the history of those symptoms will render this division unnecessary. It will I hope be more useful to divide the patients affected with the disease into three classes.
The first includes those in whom the stimulus of the miasmata produced coma, languor, sighing, a disposition to syncope, and a weak or slow pulse.
The second includes those in whom the miasmata acted with less force, producing great pain in the head, and other parts of the body; delirium, vomiting, heat, thirst, and a quick, tense, or full pulse, with obvious remissions or intermissions of the fever.
The third class includes all those persons in whom the miasmata acted so feebly as not to confine them to their beds or houses. This class of persons affected by the yellow fever was very numerous. Many of them recovered without medical aid, or by the use of domestic prescriptions; many of them recovered in consequence of a spontaneous diarrhœa, or plentiful sweats; many were saved by moderate bleeding and purging; while some died, who conceived their complaints to be occasioned by a common cold, and neglected to take proper care of themselves, or to use the necessary means for their recovery. It is not peculiar to the yellow fever to produce this feeble operation upon the system, It has been observed in the southern states of America, that in those seasons in which the common bilious fever is epidemic “no body is quite well,” and that what are called in those states “inward fevers” are universal. The small-pox, even in the natural way, does not always confine the patient; and thousands pass through the plague without being confined to their beds or houses. Dr. Hodges prescribed for this class of patients in his parlour in London, in the year 1665, and Dr. Patrick Russel did the same from a chamber window fifteen feet above the level of the street at Aleppo. Notwithstanding the mild form the plague put on in these cases, it often proved fatal according to Dr. Russel. I have introduced these facts chiefly with a view of preparing the reader to reject the opinion that we had two species of fever in the city at the same time; and to show that the yellow fever appears in a more simple form than with “strongly marked” characters; or, in other words, with a yellow skin and a black vomiting.
It was remarkable that this fever always found out the weak part of every constitution it attacked. The head, the lungs, the stomach, the bowels, and the limbs, suffered more or less, according as they were more or less debilitated by previous inflammatory or nervous diseases, or by a mixture of both, as in the gout.
I have before remarked, that the influenza, the scarlatina, and a mild bilious remittent, prevailed in the city, before the yellow fever made its appearance. In the course of a few weeks they all disappeared, or appeared with symptoms of the yellow fever; so that, after the first week of September, it was the solitary epidemic of the city.
The only case like influenza which I saw after the 5th of September, was in a girl of 14 years of age, on the 13th of the month. It came on with a sneezing and cough. I was called to her on the third day of her disease. The instant I felt her pulse, I pronounced her disease to be the yellow fever. Her father was offended with this opinion, although he lived in a highly infected neighbourhood, and objected to the remedies I prescribed for her. In a few days she died. In the course of ten days, her father and sister were infected, and both died, I was informed, with the usual symptoms of the yellow fever.
It has been an axiom in medicine, time immemorial, that no two fevers of unequal force can exist long together in the same place. As this axiom seems to have been forgotten by many of the physicians of Philadelphia, and as the ignorance or neglect of it led to that contrariety of opinion and practice, which unhappily took place in the treatment of the disease, I hope I shall be excused by those physicians to whom this fact is as familiar as the most simple law of nature, if I fill a few pages with proofs of it, from practical writers.
Thucydides long ago remarked, that the plague chased all other diseases from Athens, or obliged them to change their nature, by assuming some of its symptoms.
Dr. Sydenham makes the same remark upon the plague in London, in 1665. Dr. Hodges, in his account of the same plague, says, that “at the rise of the plague all other distempers went into it, but that, at its declension, it degenerated into others, as inflammations, head-ach, quinsies, dysenteries, small-pox, measles, fevers, and hectics, wherein the plague yet predominated[32].”