quito, and the culex that rectly from such places does not transmit malaria. Resting position of culex (bottom) and anopheles or malaria mosquito (top). to the food in the kitchen, dining-room, or wherever exposed, is it strange that disease results? The hairy legs and bodies of the flies furnish excellent places of lodgment for dirt and filth, and when the fly walks over the bread, jelly or other food, he is literally wiping his feet on these materials. Now, if the discharges from a case of typhoid fever, or the sputum from a consumptive, happen to have been walked over by the fly some time prior to meal-time, it is not difficult to see how the food may become directly infected with the germs of these diseases. It only remains for the person eating such infected food to be in a susceptible condition to become a victim of the disease. To prevent the spread of disease by flies, it is necessary, then, to keep the flies away from the foods and out of the house by careful and thorough screening; to reduce the number of flies by destroying their breeding-places as far as possible; and to disinfect all discharges from ཨཡཉྩནྟེ ཧོསོ ཨཤི...... Fig. 385. Stegomyia fasciata, the yellow fever mosquito. the body which can possibly contain the germs of disease, SO that, should the flies come in contact with such filth, the vitality of the germs will have been destroyed. Spreading of disease by mosquitos. Malaria and yellow fever are spread entirely through the bite of certain species of mosquitos. In the case of malaria, the mosquito, in order to transmit the disease, must be of a particular kind (anopheles), and must have bitten a person some time previous, said person having in his blood the plasmodium or germ of malaria. The germ undergoes certain necessary stages in its life-history in the body of the mosquito. When the mosquito bites a person, it injects into him some saliva containing the germ, at the same time that it sucks out the blood of the victim. Then the germ passes through other stages in the blood of the person bitten, these stages corresponding in a rather definite order to the symptoms of the disease. To prevent the spread of disease by the mosquito, it is necessary to destroy all pools, puddles and stagnant water by careful drainage, and by the removal of all old cans or bottles which may collect water during a rain; to treat breedingplaces with insecticides, or to introduce some nat Actual Fig. 386. The malaria mosquito. ural enemy of the mosquito, as the dragonfly, into the breeding pools, such as will devour the eggs or larvæ forms ("wiggle tails"); to cover rain-barrels or other vessels designed to hold water about a house, which may stand long enough for mosquitos to deposit their eggs therein; and to cover carefully with mosquito-netting every patient suffering with malaria. The house should always be wellscreened. The screen must be fine enough to keep the mosquito out. The so-called "fly screens " will not keep out all forms of mosquito. To treat a pond or any large body of water with oil, it is best to use what is called "fuel oil" of rather low grade, such as the Standard Oil Company calls "light fuel oil." It is allowed to spread over the entire surface of the water. If the female attempts to lay her eggs in the oil-covered water, she perishes and the eggs perish with her. Small quantities of water, such as are contained in rainwater barrels, small duck ponds, and the like, may be treated with ordinary coal-oil, as large quantities would not be required. Farm animals in their relation to health. Every precaution should be taken to keep all animals on the farm in good health. All the sanitary laws applicable to the human animal apply to the lower animals as well. Many diseases may be transmitted from man to the animals, and vice versa. Hogs and cattle known to be diseased should be killed, and their bodies disposed of in a sanitary manner. Burying such animals is not recommended. The best way is to destroy by burning. The germs of anthrax and tuberculosis may remain alive in the ground indefinitely. Both of these diseases are presumably transmissible to man. Glanders is a disease that is also transmissible, with very serious results in man. Tetanus (lock-jaw) affects both animals and man, and animals suffering with this disease must be treated accordingly. Great care must be used in the disposal of bodies dead of this disease. Dogs, cats and poultry are subject to diseases, many of which produce effects on the human body. Hence, close contact between the animals and the household should be carefully guarded against. It is the sick animal that usually gets the most attention, and at such times comes in very close contact with the interested persons. Absolute cleanliness and the generous use of disinfectants are the recommendations for such instances. Fig. 387. Pond in pasture, having common forms of algae, blue-flag and bullrush. Not a good water. THE CONTAMINATION OF WATER and a part by H. L. Russell During the last decade a widespread interest has been expressed in all parts of the country with reference to securing sanitary water for drinking purposes. Not only does this apply to water used for human consumption but also to that used for stock. A large number of human as well as animal diseases may be attributed to the poor quality of water. This is true on the farm as well as in villages and cities. The city population is indirectly interested in having a good water-supply on the farm, because contagious diseases, as typhoid fever, diphtheria and scarlet fever, are milk-borne, and at least in typhoid fever the water may be responsible. Epidemics of typhoid fever have been attributed to the use of milk which had come in contact with water containing the typhoid fever organisms. If it is known that typhoid fever has been on the premises of the dairyman, he is indirectly responsible for the conveying of the disease. The colon bacillus, the Fig. 389. Two cells of spirogyra. One of the green algae found in running brooks and streams. The chlorophyl arranged in a spiral band. After Atkinson. normal inhabitant of the intestinal tract, is sometimes the cause of poorly defined intestinal disorders. Water may contain the colon bacillus because of the presence of the bacillus in the feces of cattle and man. It is well known that anthrax, hog cholera and other intestinal diseases of the lower animals may be conveyed through drinking-water, and every one of the bacterial diseases is more or less likely to be car morum. One of the green alga found in water, sometimes forming waterbloom. (1) Gelatinous membrane. (2) Cilia or flagella. After Pringsheim. ried in this way. It is certain Fig. 390. Pandorina that anthrax is thus frequently conveyed. In one case known to the writer, the animals that died of anthrax were buried on the side of a hill. The rains of the following season removed the soil and carried the virulent spores down to the fields below, affecting not only the meadow, but also the water. In addition to these well-defined diseases, there are those that are caused by drinking-water that contains impurities from decomposed products of such diseases as hog cholera, swine plague and chicken cholera. Cattle drinking this water may be afflicted with diseases that belong to the type known as cedema, or they may be poisoned with ptomaines. This occurs most frequently when cattle are allowed access to drinking-water from sloughs and ponds. The farm should have as good supply of water as either the city or village. Usually this supply is not difficult to secure, since there is less opportunity for pollution, especially when there is a large water-shed with few buildings or dwellings. The farm water-supplies come chiefly from the following sources: mountain springs, whose sources are undoubtedly beyond the danger of pollution; lowland springs; streams; irrigation ditches; lakes: ponds; wells. From a biological standpoint, four sources of pollution must be taken into consideration, flowering plant Fig.391. Clathcontamination, algal contamination, bacterial contamination and animal contamination. Any one of these may result in injury to man or animal. Contamination by flowering plants. rocystis. One of the bluegreen algae, the cause of pigpen odor: common in reservoirs during the summer months. After Moore. The flowering plants usually found in water-supplies are practically harmless, except as they produce, through decomposition, products that may result in what is called stagnant water; but this condition seldom takes place when the surroundings are well kept. In many sections of the country, however, the growth of weeds in lakes that at some time have been low is regarded as not only unsightly, but also as injurious and detrimental to health. The plants that are generally found in these waters are: The fresh-water eel-grass (Vallis are spores, taken from the filament on the left. The clear cell in the filament is a heterocyst. After Atkinson. One (Fucus), used in making commercial iodine. The Spirogyra, or water-silk (Fig. 389), a fresh-water alga, is a thread-like organism with many cells, having the chlorophyll arranged in a spiral band. It is a troublesome weed in watercress beds. The Cladophora, a branched green alga, is also abundant in pools, and is sometimes troublesome in the same way. One of the most common of the green alga found in fresh water is the Pandorina. (Fig. 390). This often forms green scum stagnant ponds, making such water injurious to farm stock. It consists of colonies inclosed in a gelatinous membrane, the organism moving about by means of cilia that extend through the membrane. Allied to the Pandorina are other algæ found in similar places, the Pediastrum and the Volvox. In high northern altitudes the "red snow" is caused by an alga known as Sphaerella nivalis. The green algæ are not so troublesome as the blue-green algæ. It is thought that the green algæ, unless decomposition occurs, are beneficial rather than injurious to the water, as they dispose of many organic substances. Fig. 393. Nostoc paludosum. One of the gelatinous masses. on The blue-green algae are of many different forms. One of the most common is Oscillatoria, found in water-troughs and when water collects on tanks; it consists of many cells joined together in a filament, and multiplies by cell-division. While it is blue-green in color, in a mass it may appear dark, blackish green. One of the most obnoxious of the blue-green algae is Clathrocystis (Fig. 391). This forms colonies, solid at first, but later becoming perforated. The Nostoc (Figs. 392, 393) forms gelatinous masses sometimes the size of a small tomato, which may be seen floating in the water. It consists of irregular, interwoven filaments inclosed in a gelatinous mass. Related to the Nostoc is the Anabæna, consisting of filaments free or united in a mass. The condition most favorable for the development of the Clathrocystis and Anabæna (Fig. 394) algæ is a warm temperature from June to September. These plants sometimes form scums on the surface of the water or occur as floating masses. They produce what is called the "pigpen" odor, causing the water to be objectionable for domestic purposes as well as very disagreeable, as the odor can be detected at a long distance. There are cases of suspected poisoning from these blue-green algæ, as have been reported by Dr. Arthur from southern Minnesota and northern Iowa. For sanitary purposes, the odor-producing algæ should be distinguished. This odor is due to the production of essential oils by these plants, that impart very undesirable qualities to water-supplies. Herein lies the chief contaminating influence of algæ. Fig. 394. Anabæna. One of the bluegreen odor-producing alge. After West. In addition to the green and bluegreen algæ, many waters contain diatoms (Fig. 396). These form brownish scums, but are not injurious. The cell-walls of diatoms contain a large quantity of silica. Bacteria of water-supplies. The bacterial content of water varies greatly. Statistics show that artesian wells contain fewer organisms and hence furnish a purer supply of water than is found in any other source. In the representative artesian wells in Iowa, it is found that the number varies from 0 to as many as 40 or 50 organisms per cubic centimeter. The reason for the small number is that the water is constantly flowing. Artesian wells from which the water is not flowing constantly contain a larger number of organisms, due to the fact that organisms are brought from the surface in pumping. From a study of the deep wells in various parts of the country, it is found that the number of organisms is generally less than in shallow wells. In the water from a well 2,300 feet deep, supplying the College of Agriculture at Ames, Iowa, there were found 50 to 250 organisms per cubic centimeter (about cubic inch). Frankland found in a Kent county (England) well sunk in chalk 6 to 26 organisms per cubic centimeter. In a deep well at Grinnell, Iowa, the number was 0. In a well near the college at Ames, Fig. 395. Stonewort (Chara fragilis). One of the green algae. Part of a filament. It is a large, weedlike plant, often conspicuous in ponds. 114 feet deep, the number of organisms was 14,750 per cubic centimeter, while another well not far distant, at the same depth had only 31 organisms per cubic centimeter. It is evident that in cases where a large number occur there must be a leak in the pipe or a subterranean channel connecting with the source of water-supply. Of course these organisms may or may not be pathogenic or diseaseproducing, and the mere number of organisms is not a measure of the injuriousness of water; but these and the One following statements show how readily contamination may take place. Fig. 396. Navicula. diatoms forming free brown masses in water. After Shallow wells are frequently contaminated with a large number of organisms. A certain well at a depth of 40 feet was found to contain 160 to 1,100 bacMoore. teria per cubic centimeter. Another well, 10 feet deep, contained as many as 8,000 bacteria per cubic centimeter. Large open wells that have not been used are frequently contaminated, though these wells may be 40, 50 or even 60 feet deep. In many shallow wells the colon bacillus and acid-producing species occur. It should be mentioned in this connection that it is difficult to make any exact statements as to the number of microorganisms and extent of sewage contamination in the water in shallow wells, because conditions frequently change. In the case of deep wells the question is very different, since they are not subject to such frequent fluctuations. Rivers usually contain a large number of organisms. The Skunk river, an Iowa stream, in February contained 1,500 to 1,900 bacteria per cubic centimeter. The Des Moines river in March contained 1,200 to 1,400 bacteria above the sewage outlet, while below it contained 7,770 to 87,500 organisms per cubic centimeter. Frankland states that in one instance the river Ure, in York county, England, contained 1,800 bacteria per cubic centimeter above Ripon, while below it contained 33,400 bacteria per cubic centimeter. Other figures might be added to show the farmer the importance of disposing of the sewage in some other way than by dumping it into the rivers. The water of many streams is rendered unsafe because of such pollution. The farmers utilize the water from these streams, and when such water is used disease of some kind is likely to follow. Certain mountain rivers, examined by the writer in 1905, had organisms varying in number as follows: Gunnison river, 1,750 to 1,820 organisms per cubic centimeter; Arkansas 200 Fig. 397. Staphylo coccus pyogenes. Common pus organism sometimes found in water. river, 28,000 to 45,500 organisms per cubic centimeter. This water was extremely muddy. The Mississippi river contained 2,000 to 9,600 or more; Green river, Washington, contained 28,000 to 32,000 organisms per cubic centimeter. That germs may be carried a considerable distance is seen by the fact that typhoid fever organisms may live for several weeks in river water. Investi gators found that typhoid fever organisms were still alive in dilute sewage after sixty days; in unsterilized sewage they did not live longer than fourteen days. A common red organism, known as Bacillus prodigiosus, may be carried many miles in water, as demonstrated by Mr. Kirchner, who emptied a 40-gallon broth culture of this organism below Grafton, Ill., and found it twenty-five miles below the point of introduction. Spring water, though often said to be pure, is only found in this condition when springs have their origin in mountain regions. In a prairie country, the spring water, unless protected from surface washings, is frequently contaminated by surface drainage, especially when cattle have access to the spring. Iowa spring waters show that the number of bacteria per cubic centimeter varies from 140 to as many as 5,800. The water from the spring in which 140 bacteria per cubic centimeter were found was protected from surface washings by brick-cased walls, and was covered. The other springs were open and surrounded by herbage of all kinds. Springs protected from surface waters contain a much smaller number of organisms. They may be comparable to A common organism found in water. Produces fluorescent pigment. Flagella are found at the end of the rod. After Fischer. deep or artesian wells. Fig. 398. Bacillus fluorescens. Cramer found in springs in Zürich that the number of organisms varied from 9 to 45. A spring investigated by the writer on the North Yakima river, Washington, contained 104 to 220 organisms per cubic centimeter. A spring in a dense forest near Creighton, Oregon, contained 1,200 to 1,500 bacteria per cubic centimeter. This was an open spring surrounded by herbage and decomposing leaves. It is said that fresh-water lakes contain fewer germs than river water. In Lake Zürich there was found, from October to December, an average of 184 organisms per cubic centimeter. Many other European lakes, however, show a much larger number. Near the shore-line of this lake there is said to have been found 16,000 bacteria per cubic centimeter. In Lake Washington, near Seattle, close to the shore the writer found 16,000 to 20,000 bacteria per cubic centimeter. Railroad water-supplies need attention, for the farmer is deeply interested in the purity of the water supplied to his stock by the railroads when shipping. When the wells are deep and water is constantly pumped, there is very little danger from contamination. On the other hand, when shallow wells are used and when they are in close proximity to the stock-yards, contamination is certain to occur. In a number of railroad wells between St. Paul, Minnesota, and Billings and Miles City, Montana, there was found an unusually good supply of water. The number of organisms in wells at Billings varied from 2,450 to 4,200, and at Miles City from 80 to 2,450. An investigation of railroad watersupplies in Iowa showed some wells to be contami nated with the colon bacillus. In most cases the colon bacillus was absent and gas was not formed. In a few instances, however, the colon bacillus and acid-producing species were abundant. The presence of the former indicated contamination with excreta. Such water frequently causes disorders among stock in shipping. A further discussion of water bacteriology. (By H. L. Russell.) datum line The bacterial content of water is primarily dependent on the germ content of the soil. The upper layers of the soil abound in germ life, the amount of which depends on the nature and origin of the organic matter present. The processes of decomposition that are continually operative in these layers suffice to seed the upper strata richly with these lower forms of life, and, as suitable and sufficient food is present, a marked development occurs. While this condition obtains at or near the surface, the germ content diminishes rapidly as the depth increases, so that the soil a few feet deep is practically free from all kinds of organisms. As water falls through. the air in the form of rain, hail or snow, it collects many floating particles, including bacteria. When it reaches the earth, it either percolates into the soil or flows, over the surface of the ground. In the latter case it becomes highly charged with soil bacteria, and, as a consequence, the water in streams, rivers and even lakes is relatively rich in these organisms. Naturally, the germ content bears a more or less definite relation to the load of sediment held in suspension. Streams that are turbid by reason of high water, or because of the character of the soil, have a much higher bacterial content than clear water streams. When the load of silt is deposited, as in a sluggish stream or lake, the germ content rapidly decreases. datum line The water which percolates into the deeper soil layers has its initial content largely removed by mechanical means. Conditions are also unfavorable for the development of life. Therefore, by the time it reaches that underground water reservoir known as the ground water-supply, it is generally free from all kinds of organisms, and is markedly different from a surface supply, so far as its biological character is concerned. When this practically sterile ground water is tapped, as in a well, opportunity for bacterial infection is sure to occur. The drilling of the well introduces organisms from the outside, but these soil forms do not thrive long in water, and in the course of a few months nearly all of them disappear except those species that are distinctively adapted to these surroundings. This is particularly true when the well is much used, as the process of pumping draws on the supply of germ-free water in the soil. This condition results in the bacterial content of properly constructed wells being low, while in the open dug well it is usually higher, even though no external contamination of a dangerous kind may have occurred. Springs also have a relatively low bacterial content because of their origin from the soil water. The differences, therefore, that exist in normal surface streams and unpolluted subterranean waters are so marked that a bacteriological examination aids materially in determining whether or not a supposedly unpolluted water is contaminated with surface drainage. The problem of water bacteriology is to recognize those forms of bacteria that are detrimental to man and animal life that are disseminated through the medium of water. The types of disease-producing organisms that are spread in this way are those that find a suitable location for development in the alimentary canal. Water becomes polluted with these organisms generally through the dejecta, in some cases by means of the Fig. 399. Poor location for well. Fig. 400. Good location for well. liquid as well as the solid excreta. Surface waters, therefore, are very much more likely to be infected than those of subterranean character, unless the opportunity for the introduction of surface drainage exists. Typhoid fever and cholera are unquestionably the most important diseases of the human type that are spread in this way; anthrax, hog cholera, and other intestinal diseases, the leading ones among stock. It is exceedingly fortunate that most intestinal diseases of this class are confined in the main to one species of host. Thus, hog cholera and swine plague affect only swine, while typhoid fever and cholera are confined to the human. Anthrax assumes an intestinal form in animals, but in man it is localized generally as a malignant pustule. For this reason, the possibility of interchange of disease between man and varying kinds of stock is materially lessened. The recognition of these specific disease-producing organisms in water is attended in some cases with especial difficulty. This is due in part to the fact that most organisms of this class do not find favorable growth conditions in water, especially when it does not contain a large amount of organic matter. It is largely, then, a question as to how long the disease bacteria can retain their vitality in such a medium. Various factors are more or less effective in hastening the death of these dangerous organisms. The germicidal influence of direct sunlight, the lack of suitable and sufficient food supplies, the antagonistic effect of the by-products formed by the inherent soil and water bacteria, as well as the effect of dilution and sedimentation, are all factors which tend to shorten the vitality and reduce in numbers the disease-breeding species. |