Many of the Irish writers often speak of having seen typhus fever occurring several times in the same individual. Dr. Stoker speaks of the poor as having frequent attacks of fever, in the course even of a short life, and thinks that few adults have escaped these attacks, although he has no doubt that the succeeding attacks are milder than the first. Dr. O'Brien, in one of his hospital reports, says: "Some of the nurses have had the disease three or four times." Others have remarked that a second attack of the disease is very rarely witnessed when the first had been severe, or when it had been attended by an abundant eruption. And there seems good reason for believing that such is the case. Dr. Barker, in his Report of the Cork Street Hospital, Dublin, states that he has for some time entertained the opinion that sufferers from fever, attended with the petechial eruption, if they are not altogether secured by it from a second attack, are not at least so liable to it as those who have had a fever of the ordinary kind. "Though I have frequently made the inquiry," he adds, "I have not found a patient in whom this symptom was distinct, who had suffered from the same fever on any former occasion. But, whatever may be the result of more minute inquiry, it may be asserted that the chances of the recurrence of fever diminish in proportion to the continuance and severity of the first attack." Dr. Bracken, of Waterford, after quoting the above, says: "It appears to me that this opinion is supported by experience, as well as by reasoning from similar facts. Since I first observed this remark, I have kept the subject in view, and, after some attention to it, I have not been able to ascertain that more than three persons, out of many hundreds who came within my observation, have had relapse or recurrence of fever, after being previously affected with the symptoms in question." Dr. Trotter says: "During our extensive and long experi ence of the origin, progress, and extinction of contagion, in ships, and everywhere else, I have entertained a strong suspicion that typhus infection very seldom affects a person more than once in a lifetime." Dr. Perry, of Glasgow, in a letter to the editors of the Dublin Journal of Medical Science, says: "I have for some years entertained the opinion, founded upon an extensive series of observations, that contagious typhus is an exanthematous disease, and is subject to all the laws of the other exanthemata; that, as a general rule, it is only taken once in a lifetime, and that a second attack of

Barker and Cheyne's Account, etc., vol. i. p. 241. 2 Medecina Nautica, p. 213.

typhus does not occur more frequently than a second attack of smallpox; and, judging from my own experience, less frequently than a second attack of measles or scarlet fever."

SEC. VI.-Age. There is no evidence that this disease is confined to any period or periods of life. During its prevalence at Philadelphia, in 1836, children were rarely attacked by it; but after childhood, age seemed to exercise little or no influence upon the susceptibility to the disease. Amongst the whites, where the age could be better ascertained than amongst the blacks, there were as many patients over thirty-five years old as there were under this age. Dr. Edward Percival, in his Report on the Epidemic Fevers of Dublin, at the Hardwicke Fever Hospital, during the year 1813, 1814, and 1815, says that the disease prevailed continually amongst the boys and girls of the Bedford Asylum; characterized by petechiæ, great failure of strength, a turgid countenance, and considerable stupefaction.' Eleven hundred of these children were crowded together in a building originally intended to accommodate only six hundred. Of three thousand nine hundred and seventy patients, received into the Cork Street Hospital, Dublin, in 1817 and 1818, there were under ten years of age three hundred and sixty-two; from ten to twenty years, fourteen hundred and seventyfour; from twenty to thirty years, twelve hundred and sixty-five; from thirty to forty years, five hundred and eight; from forty to fifty years, two hundred and forty-one; and over fifty years, one hundred and twenty. Dr. Barker says that, in the course of the epidemic of the above-mentioned years, he witnessed the disease in many children under the age of four or five years, and in its most exquisite form-that of petechial fever. It will be found from extensive observations, that a large proportion of the cases of typhus fever occur in persons who are between the ages of fifteen and thirty years; but it would be very unsafe to infer from this fact anything positive as to the liability of different ages to the disease, unless we have first ascertained the whole number of persons of these different ages exposed to the causes of the fever. From not attending to this and other circumstances in these calculations-from not taking into account all the elements of the problem to be solved many writers have lost themselves on what Dr. Arrott, of Dundee, calls the "quicksands of false arithmetic."

1 Trans. of Phys. of Ireland, vol. i. p. 288.

2 Ibid., vol. ii. p. 533.

The average age of forty-seven patients, in whom the disease proved fatal at the Royal Infirmary of Edinburgh, in 1838 and 1839, was thirty-five years and a half, nearly.'

SEC. VII.-Sex. The influence of sex in predisposing to typhus fever is not very great. It has been generally remarked by Irish observers, that the disease is somewhat more common amongst females than it is amongst males. This fact may be in part, perhaps entirely, accounted for, by the more constant exposure of the females to many of the most active causes of the disease. From Dr. Mateer's statistics, it appears that, of 9588 patients admitted into the Belfast Fever Hospital between May, 1813, and May, 1835, inclusive, 5130 were females and 4458 were males. Dr. Harty gives a table of the admissions and deaths of the two sexes, at some of the principal hospitals of Ireland, from 1817 to 1819. The number of males admitted was 32,144; the number of females 34,398. The male mortality was one in 19.40; the female, one in 24.75.* In connection with this subject, Dr. Harty remarks that, "though it is well ascertained that the epidemic spared neither age, sex, nor condition, and that all were indiscriminately exposed to its attacks, it is yet certain that there were particular periods of the epidemic season, during some of which children, during others adult females, and during others adult males predominated in number."3

SEC. VIII.-Recency of Residence. New residents in any given locality seem to be somewhat more liable to typhus than others, although this circumstance has so little influence that it has not been often spoken of by British writers. According to a table published by Dr. Davidson, of five hundred and sixty-eight patients with typhus, admitted into the Glasgow Fever Hospital, in 1838 and 1839, one hundred and seventy-six, or one-third, nearly, were natives of the city; one hundred and ten had been residents less. than six months; fifty-five, from six months to a year; ninety-seven from one year to five; and one hundred and thirty, from five years to twenty and upwards. Thus more than half of the whole number had lived in the city five years or upwards.

4

1 Ed. Med. and Surg. Journ., Oct., 1839.

2 Historic Sketch, etc., p. 29.

Dunglison's Medical Library.

3

Ibid., p. 31.

CHAPTER V.

VARIETIES AND FORMS.

THE most common varieties of typhus fever are such as depend upon different degrees of severity, and such as are more or less constantly connected with the different seasons of the year. The proportion of mild to grave cases varies considerably under different circumstances, but it is almost always very great. Cases of all degrees of intensity, from the mildest to the most severe and malig nant, just as happens so frequently with scarlatina and smallpox, are often found together, under the same circumstances, and apparently depending upon similar causes.

During the winter and spring, the disease is more likely to be seriously complicated with pulmonic affections. In the summer and autumn, it is frequently associated with gastro-intestinal irritation. The disease, in certain places, and for a limited period of time, is occasionally marked by certain peculiarities. Dr. John Cheyne remarks that he never witnessed continued fever with so many inflammatory symptoms, as in the spring and summer of 1816, at Dublin; and that the blood was sizy in nearly one-half of the patients who were blooded. In August and September, the cases were often complicated with dysentery, and with symptoms of gastro-hepatic derangement. A distressing nausea was common, with a bitter or foul taste, and a yellow tongue. After this period, the fever became more severe in its character, and was frequently complicated with an inflammatory state of the bowels.1 In December, and the following January, many cases were attended with inflammation of the bronchial mucous membrane. The same writer says that, of one hundred and seventy-five patients admitted into two wards of the Hardwicke Hospital during the months of April, May, and June, 1818, at least three-fourths had cough, with pains or stitch, oppression in the chest, and quickened respiration." But these varieties are in no degree more numerous or more important

1 Dub. Hosp. Rep., vol. i. p. 15, et seq.

2 Ibid.

than those which are observed in the history of all epidemic diseases. Certain individual symptoms or phenomena may be frequent at one time and place, and rare at another. The occurrence of epistaxis, for instance, or of relapses, or of some consecutive affection, may be much more common in one season than in another. Dr. John Cheyne says of the fever at Dublin in 1816: "Relapses, which rarely occurred in summer, were uncommonly frequent in winter." During the years 1843 and 1844, there prevailed very extensively, at Edinburgh, a form of fever marked by such strong peculiarities as to excite some question as to its true character. Dr. Alison believed it to be specifically distinct from typhus. A very elaborate history of the disease has been published by Dr. Halliday Douglas, in the Northern Journal of Medicine. It was generally sudden in its attack, and rapid in its progress. One of its most striking peculiarities consisted in its tendency to terminate suddenly, after a certain period, by a critical evacuation-commonly by sweating-and after an apyretic interval to relapse. This sometimes happened twice. Of one hundred and twenty-one cases admitted into the Edinburgh Royal Infirmary during the primary attack, the period of the first crisis was ascertained in eighty-three. It occurred on the fourth day, in two; on the fifth day, in twelve; on the sixth day, in twenty-five; on the seventh day, in twenty-seven; on the eighth day, in nine; on the ninth day, in four; and on the tenth day, in four. Only six of the remaining thirty-eight are said to have recovered gradually, and not by an abrupt crisis. The crisis was in most instances preceded by a rigor or chilliness; and, in all but two cases, accompanied by a sweat more or less profuse, lasting generally for a few hours, in a few cases for two or three days. Sometimes, during the sweat, the pulse increased in frequency, but not always. The apyrexial period or intermission was quite complete in all but fifteen cases. Its usual duration was from five to seven days. The relapse was almost universal. Of one hundred and forty cases in which the time of its occurrence was ascertained, it took place between the ninth and thirteenth days of the fever, in seventeen; on the thirteenth, fourteenth, and fifteenth days, in eighty-one; and subsequent to the fifteenth day, in forty-two. The relapse was generally ushered in by a rigor, and followed by febrile symptoms, less urgent, however, and of shorter duration than in the primary attack. This relapse usually terminated by a second crisis, between the second and the fifth day inclusive, from its commencement. In eleven cases, there was a second relapse,