Part 22 (2/2)
_Cause of the disease._
Typhoid fever is a modern disease, and only for the last fifty years has it been recognized in medicine. It is caused by bacteria, and its manifestations are the results of bacterial growth in the body, chiefly in the smaller intestine. Here the toxin produces a violent poison which results in an attack of fever, lasting about six weeks. Owing to the bacterial growth, serious failings, commonly known as perforations, may develop after a severe attack, in the membranes and linings of the intestine, and the resulting inflammation is not infrequently the immediate cause of death. It is a thoroughly established fact that the disease is caused by a special type of bacteria and that if the bacteria could be killed outside the body, no transmission of the disease could occur. It is also true that if the disease germs could be destroyed within the body the patient would recover immediately, provided the toxins had not been already distributed through the system.
There are, therefore, two possible methods of doing away with typhoid fever, one by eliminating all possibility of transmission outside of the body of the patient and the other by killing the germs while in the body of the patient. The latter plan is not feasible, since no antiseptic has been found which will kill the germs without killing the patient. It has been discovered that a drug called utropin will act on the germs when located in certain parts of the body, as in the kidneys; but this drug, although very effective in destroying germs in those organs, has no effect elsewhere. In general, we must eliminate the disease by preventing its transmission from the sick to the well.
_The bacillus of typhoid._
Unfortunately, the typhoid fever germ is comparatively hardy and is not so easily killed by unfavorable environment as is the germ of pneumonia, for instance. It lives in water and in the soil, although probably it does not increase in numbers in either place. Nor will it live in the soil or in water indefinitely, and a great deal of study has been expended in trying to determine just how long typhoid fever germs will live under different conditions. It has been found, for example, that drying kills the typhoid bacillus in a few hours, although a few may survive for days. Experiments have also shown that it cannot leave a moist surface. It cannot, for instance, jump out of cesspools and drains and take to flight through the air, conveying the disease.
There is no possibility of contracting typhoid fever because a drain near the house is being cleaned out, since, so far as is known, the typhoid fever germ does not get into the air. The direct rays of the sun will kill typhoid fever germs within a few hours, although the value of this sort of disinfection is limited, because where typhoid fever germs are apt to acc.u.mulate, the turbidity of the water prevents the penetration of the sun's rays for more than a few inches.
It has been found that a high temperature kills typhoid fever germs, and even so moderate a temperature as 160 degrees Fahrenheit is sufficient to destroy them. This is the principle employed in pasteurizing milk, since it is a.s.sumed, justly, that by raising the temperature of the milk to 160 degrees Fahrenheit, for ten minutes, it will be possible to kill any typhoid fever germs present. Boiling, of course, since this involves a temperature of 212 degrees, will kill the germs, and it is for this reason that wherever a water is suspected of typhoid pollution, it should be boiled before being used for drinking. It has been found that in distilled water, that is, in water where no available food is to be had, the germs will live about a month, and that in water with organic matter present, but without other bacteria, this period may be extended two or three times. In water rich in organic matter, but where other antagonistic bacteria are also present, the typhoid germs are usually driven out or killed at the end of three or four days.
It is not unreasonable to expect that at least half of the germs discharged into a stream will live a week, and if the stream has a uniform current, so that the germs are continuously carried downstream, they will be found below the point of infection, a distance equal to that which the stream will flow in a week. This is important because it shows how unlikely it is that the germs once placed in water will die out or disappear without infecting those who subsequently drink the water. There is evidence that the typhoid germs, like all other germs for that matter, are likely to settle to the bottom of a lake or pond, and so a stream pa.s.sing through a pond will lose a large part of the bacterial pollution with which it entered. This is not positive enough, however, to insure a good water-supply, since in the spring the heavy flow of the stream will wash this deposited material out through the pond, carrying the infectious matter downstream. In addition, the upheaval of the settled material from the bottom of the lake, which occurs twice a year on account of the variation in temperature at different depths, will bring the settled germs to the top.
It has been found also that just as a high temperature destroys the germs, so a low temperature has the same effect. Typhoid fever germs in ice are practically harmless after two weeks, and since in natural ice the impurities of the water are largely eliminated mechanically, so that frozen water is purer than the water itself, there is very little chance, even when ice is cut from a polluted pond, for typhoid germs to be found alive after being in an ice house for three or four months. In the ground, the life of the bacteria is longer, and while experiments do not agree very well as to the exact length of time that the germ may live there, there seems to be evidence that they may live several months, if not a year or more. Cases have come under the observation of the writer which seemed to show that certain well waters were polluted by germs which could only have been deposited in the near-by soil nearly a year before the time of the consequent outbreak.
Entirely to deprive the germs of life, therefore, it is necessary, inasmuch as they are so widely distributed, to act promptly and at once disinfect the fecal discharges from the patient rather than to wait until those discharges have been thrown into a stream or onto the ground and then attempt disinfection. There is probably no more important thing in stopping the spread of typhoid fever than to practice carefully disinfection in the sick room, using b.i.+.c.hloride of mercury and chloride of lime, as already described in Chapter XV. Since, however, such disinfection is not always practiced and since care must be taken to avoid the introduction of the germs into the system, it is well to know how, a.s.suming that they have not been killed in the sick room, they make their way from that place to a healthy individual.
_Methods of transmission of typhoid._
There are three main avenues used by the germ, namely, water, milk, and flies, and of these three, the first is by far the most important and includes probably 80 per cent of all the cases. The reason for this is twofold. First, that water is so universally used, and second, that it is so easily and generally polluted. There are many historic examples which show definitely that water once polluted by typhoid germs is able to spread the disease far and wide.
The epidemic in Ithaca, New York, is a good example and ranks as one of the most serious that this country has ever known. The water-supply of the city is taken from a small stream, Six Mile Creek, which is a surface water with a drainage area of about 46 square miles. The stream is polluted to a large extent. About 2000 persons live on the watershed, and there are many houses practically on the bank of the stream which runs for a large part of its course at the bottom of a valley with steep side slopes. At the time of the epidemic, 1903, a dam was being built on the stream about half a mile above the waterworks intake, and while no proof of the fact could be found, it was generally supposed that some of the Italians working on the dam were affected with typhoid fever and had polluted the water. However, there were on the banks of the stream, farther up, no less than seventeen privies, and it was known that there were at least six cases of typhoid fever during the season just previous to the epidemic. During the month of December, 1902, a heavy rain occurred, so that any pollution on the banks would naturally have been washed down into the stream. On the 11th of January, the epidemic broke out through the town and by the middle of February there were some 600 cases reported in a population of 15,000. The number of deaths from this epidemic was 114, and there is reason to suppose that the number of cases was double the number reported by the physicians. After the water from the creek was shut off and after the citizens had been persuaded to boil all water used, the epidemic stopped and the installation of a filtration plant has prevented any recurrence of the epidemic.
In 1880, a severe epidemic occurred in Lowell, Ma.s.sachusetts, and was traced to an infection of the river from which the city's water-supply was taken. This was definitely shown to have come from a small tributary of the Merrimac River, and the particular infection responsible for the epidemic was traced to a small suburb named North Chelmsford, where one case of typhoid fever occurred in a factory, the privy of which was located directly on the bank of the small tributary.
In 1900, an epidemic of typhoid occurred at Newport, Rhode Island, through the pollution of a well, and about 80 persons were affected, most of whom lived within a radius of 300 feet of the well and all of whom used the well water. The well was a shallow one with dry stone sides and a plank cover, and surrounding the well were about 20 privies, the nearest one only 25 feet away. The water in the well was 2 feet below the surface of the ground. It was found that a month before the epidemic broke out, there had been cases of typhoid fever in houses adjacent to the well, and that discharges from the typhoid patients found access to the privy vault which was only 25 feet from the well. It was practically certain that the well was infected by the leechings of these privies, particularly from the one only 25 feet away.
[Ill.u.s.tration: FIG. 77.--Spring infected by polluted ditch.]
Another example of the way in which underground waters, such as springs, may become contaminated is described by Whipple as occurring at Mount Savage, Maryland, in 1904. Through this village ran a small stream known as Jennings Run, which was grossly contaminated with fecal matter.
In July, 1904, a woman who had nursed a typhoid patient in another town came home to Mount Savage, ill with the disease. She lived in a cottage on the hillside above the stream, and the drainage of the cottage was conveyed through an iron pipe onto the ground just above the stream.
Figure 77 (after Whipple) shows the relative positions of the cottage and stream. Heavy rains occurred during the first week in July which probably washed the infectious matter from the ground into the ditch and then through the ground into a spring just below down the slope. A week afterwards twenty workmen who had been drinking water from the spring came down with the fever and new cases occurred daily for a week or two.
An interesting epidemic occurred in Ma.s.sachusetts, caused by a farmer's boots carrying infectious matter from recently manured fields onto the well cover, whence it was washed into the well by repeated pumping.
The moral of these incidents is very plain, namely, that where any possibility of the infection of drinking water occurs, that water ought either to be avoided or else to be thoroughly sterilized before using.
This applies particularly to the old-fas.h.i.+oned well,--the kind with loose board covers and chain pumps.
_Construction of wells in reference to typhoid._
Two points already mentioned are essential if well water is to be kept pure. One is to line the well with a water-tight masonry lining, and the other point is to have the cover of the well made with a thoroughly water-tight coating. This does not always give full protection, since in some cases polluting matter may pa.s.s through even ten feet of soil.
This would be particularly true if the well was in a fissured or seamed rock, and very recently the writer found a well dug in a laminated granite, where a near-by sewer, leaking at the joints, contaminated the water of the well, although the well was cased with an iron casing twenty-five feet deep. The sewage escaped into a crack in the rock and followed the crack down vertically and horizontally into the well.
Limestone is even more dangerous if any pollution exists in the vicinity. In cases where a well goes down to a horizontal layer of limestone and where a privy vault is dug to the same rock, it is found that pollution will follow the surface of the rock horizontally a long distance, and this condition of things always makes a well water suspicious. In sand or fine gravel, on the other hand, the danger of contamination is almost negligible; on Long Island, for example, the cesspools and well are both dug ten or fifteen feet deep and only fifty feet apart without any trace of contamination being detected.
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