A system of practical medicine. By American authors. Vol. 1

by Unknown

²⁴ Murchison.

²⁵ Handbuch der Historisch-Geographischen Pathologie, Stuttgart, 1881.

Most authors agree with the statement made by Murchison, that typhoid fever is unusually prevalent after summers remarkable for their dryness and high temperature, and that it is unusually rare in summers and autumns which are wet and cold. Certainly, the severest epidemic of the disease which has been observed in Philadelphia in several years occurred in the year 1876, during and after a summer of exceptionally high temperature, and one characterized by a decidedly diminished rainfall. Still, there can be no question that the increased prevalence of the disease at this time was due, in part at least, to the crowded condition of the city consequent upon the Centennial Exhibition. In 1872, although the mean of the summer temperature was slightly higher than that of 1876, the disease did not prevail in an epidemic form. This may be explained by the fact that the rainfall of the summer months of this year was decidedly greater than the average. Hirsch, however, attaches much less importance to temperature as a factor in the production of typhoid fever than most other authors. He says that he has found, from a comparison of a large number of epidemics, that the disease occurs almost as often in cool as in hot summers, in cold as in warm autumns, and in mild as in severe winters. Murchison, moreover, admits that mere dryness of the atmosphere is not conducive to an increase of typhoid fever. On the contrary, he says, warm, damp weather, when drains are most offensive, is often followed by an outbreak of the disease.

The relation which temperature and moisture bear to the causation of typhoid fever is therefore not definitely ascertained. It is certain, however, that the largest number of cases does not occur at the period of the greatest heat, but is usually not observed until from six weeks to two months afterward, and the minimum is not reached until about the same length of time after that of the most intense cold. This difference in time Murchison explains by the hypothesis that the cause of the disease is exaggerated or only called into action by the protracted heat of summer and autumn, and that it requires the protracted cold of winter and spring to impair its activity or to destroy it. On the other hand, Liebermeister, who believes that the breeding-places of typhoid fever lie deep in the earth, holds that the time is consumed in the penetration of the changes of temperature to the place where the typhoid poison is elaborated, in the development of the poison without the human body, and in the period of incubation. In some places the maximum of the disease is observed earlier in the year than in others. In Berlin, for instance, the largest number of fatal cases occurs in October, while in Munich it does not occur until February. This depends, he thinks, upon the difference in the distance beneath the earth's surface of these breeding-places in different localities, and the deeper they are the longer, he says, will it be before they are affected by the heat of summer or the cold of winter, since the changes of the temperature of the air are followed by corresponding changes in the temperature of the earth more and more slowly the deeper we go beneath the surface.

Buhl and Pettenkofer have, as the result of a series of observations carried on in Munich over a number of years, reached the conclusion that an intimate relation exists between the variations in the degree of prevalence of typhoid fever and the rise and fall of water in the soil. When the springs were low they found that there was a marked increase in the number of cases; when, on the other hand, they were high, there was just as decided a diminution. Out of this fact they have evolved the theory that the cause of typhoid fever lies deep in the soil, and has the power of multiplying itself there, and that this property is very much increased when the water-level sinks, and the upper layers of the earth are consequently exposed to the air. It is, on the contrary, diminished when the water-level rises and the earth is again saturated with moisture. It is unquestionably true, as has already been stated, that it is principally after hot and dry weather, when the springs are of course low, that typhoid fever is most prevalent, and that it very frequently subsides after the occurrence of very heavy rains; but it is not necessary to adopt the theory of Buhl and Pettenkofer to explain these facts. It seems quite as probable that the increased prevalence of the disease after dry weather is due, as suggested by Buchanan and Liebermeister, to the greater amount of solid matter which is then suspended in the water of the springs. A larger proportion of the germs of the disease, if there should be any present in the soil, will therefore be contained in any given quantity of the drinking-water. The theory fails to account, as pointed out by Murchison, for the connection which is frequently observed between defective house-drainage and outbreaks of typhoid fever, occurring irrespectively of any variations in the subsoil water. And, moreover, outbreaks of the disease have occurred under precisely opposite circumstances, as the outbreak at Terling in 1867, recorded by Thorne,²⁶ which was coincident with a rise in the subsoil water after drought.

²⁶ Quoted by Murchison.

It is believed in many parts of our country that there is an antagonism between typhoid fever and the various forms of malarial fever, and it is unquestionably true that in many districts in which the latter were formerly prevalent they have ceased to be frequent, and have been replaced apparently by the former. In the cultivation of the soil the causes of malarial fever disappear, or at least become less potent. On the other hand, the increase of population and the neglect of all sanitary laws in the building of towns, and the construction of sewers with their house connections, seem to favor the occurrence of typhoid fever. But there is no real antagonism between the diseases. During the recent Civil War typhoid fever was not infrequently developed in soldiers suffering from malarial disease. Indeed, so frequent was it to have the manifestations of the two diseases in the same individual that many observers at that time supposed they had a new disease to deal with, to which they gave the name of typho-malarial fever.

2. EXCITING CAUSES.—Much diversity of opinion has existed in times past and to a certain extent continues to exist, in regard to the contagiousness of typhoid fever. In the early part of this century there was quite a number of good observers, including Nathan Smith in this country, and Bretonneau and Gendron of Château du Loir in France, who held the opinion it was an eminently contagious disease. Indeed, Smith went so far as to say that its contagiousness was as fully demonstrated as that of measles, small-pox, or any other disease universally admitted to be contagious. This was also the opinion of William Budd, who maintained that the contagious nature of typhoid fever was the master truth in its history. The late Sir Thomas Watson was also a warm supporter of the same view. At the present time, however, the large majority of physicians, whose opportunities for observation give weight to their opinions, do not regard the disease as contagious in the strict sense of the word. During the past twenty-four years I have been almost uninterruptedly connected with large general hospitals, and during that time have had a large number of cases of typhoid fever under my care, and a still larger number more or less under my observation. During all this time I have never known but one case to originate within a hospital, and that occurred in a servant whose duties did not bring her in immediate contact with the sick. Murchison's experience with a much larger number of cases has been very similar. In twenty-three years, in which 5988 cases were treated in the London Fever Hospital, only 17 residents contracted the disease, and most of these had no personal contact with the sick. Liebermeister asserts that he has never known a case to originate in a hospital from direct contagion. When such cases appeared to have occurred, they could generally be traced, he says, to some defective sanitary condition of the hospital.

There are, nevertheless, many facts on record which, unless duly weighed, appear to lend a good deal of support to the theory of the contagiousness of typhoid fever. Among the most important of these are (1) the occurrence in rapid succession of several cases in the same house, and (2) the limited epidemics which occasionally follow the arrival of an infected person into a previously healthy locality. These facts are, however, susceptible of an entirely different explanation.

1. In those instances in which several cases of the disease have occurred in the same house, it not infrequently happens that some defect in its sanitary conditions is detected, or that the drinking-water is found to be impure. The same cause which produced the first case may, therefore, also have produced those which succeeded it. Indeed, the interval between the cases is sometimes so short that for this reason alone, if there were no other, they could scarcely be attributed to contagion. It not infrequently happens that the seizure of one member of a large family is followed on the next day by that of another, and on the third or fourth by that of still another. Now, while it is undoubtedly true that the period of incubation has appeared in some cases to be very short, we know that under ordinary circumstances it is usually about two weeks.