Popular Science Monthly/Volume 76/January 1910/The Transmission of Disease by Money

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THE demonstration of a few of the avenues by which infection is transmitted is among the triumphs of modern experimental medicine. By its revelations cholera is now known to be mainly a water-borne disease; likewise it is recognized that typhoid is transmitted by those means by which the waste products of an infected individual are transferred either directly or in round-about ways to the food of another; malaria is no longer thought to be wafted by the night air, but is known to be directly carried to and introduced into the system by the mosquitoes; and, even a later triumph, yellow fever is seen to approach its human victim through the same hosts; while, finally, it has been determined that bubonic plague, the scourge of the tropical east, is carried by the rat flea. Notwithstanding these recognized avenues of transmission in specific instances, many other and more common infections continue to travel from one to another by paths that we do not know.

Before the knowledge of cholera transmission by water, it would have been considered a scientific contribution to the subject to have demonstrated the absence of cholera germs in twenty-four samples of water taken at random some of which perhaps were dirty; but to-day we know that the bacteriological study of water for evidence of cholera will usually demonstrate the avenue of infection only when and where cholera is prevalent. Similarly, it would be a matter of the greatest surprise if the examinations of twenty-four or many more samples of water or food for typhoid germs revealed their presence, even if the water or food was dirty and offensive. Likewise, the most diligent search of twenty-four or more mosquitoes for malaria or yellow fever would in all probability fail to show a single malarial plasmodium or yellow fever bacillus. In the same way, hundreds of rat fleas might be caught and made to bite guinea-pigs or rats without the production of bubonic plague in a single instance. Do any of these negative observations disprove or discredit in the least degree our present views on the origin of the various diseases whose avenues of infection we have mentioned?

By what privilege then does our scientific friend, Warren W. Hilditch, of the Sheffield Laboratory of Bacteriology and Hygiene, Yale University, claim in The Popular Science Monthly of August, 1908, even the least knowledge of the transmission of disease by money from the bacteriological study of twenty-four bills, "the dirtiest I could obtain from various sources, such as railroad, trolley and theater ticket offices, banks, drug stores and individuals in different part of the state"? When the facts of the transmission of cholera and typhoid by drinking water were discovered it was not by the demonstration of the corresponding germs in water, dirty or otherwise, which was taken at random. Indeed, these demonstrations were the last and most difficult steps in the whole chain of evidence and were only successful directed to water known to have been closely associated with epidemic outbreaks of the disease. By what reasoning, then, may we expect any more ready demonstration of infected money and why should not the same outside evidence of the possibility of infection guide as in the selection of money samples to be examined? Likewise, the demonstration of malaria in mosquitoes and bubonic plague in fleas was the last, not the first step in the chain of evidence, proving the avenues of infection of these diseases. The possibility and even the probability to a high degree were previously established by other evidence so that the material examined was advantageously selected.

Precisely as with cholera and typhoid the examination of water casually selected offers practically no opportunity of proving the transmission of these diseases by the demonstration of their specific infective organisms in the samples; exactly as with malaria, yellow fever and bubonic plague the examination of mosquitoes and fleas selected at random offers no promise of proving the transmission of these diseases by these hosts; so the examination of 24, of 240 or even of 2,400 bills not selected with intelligent appreciation of the opportunity for infection will contribute nothing at all to the solution of the transmission of infection by dirty money.

Great saving of human suffering and even life has resulted from triumphs referred to; likewise, the closing of other avenues of infection will certainly act as a prophylactic measure in regard to other infections. It is particularly desirable to discover the transmitting media of the more common but no less fatal organisms, such as the germs that infect the respiratory passages, notably the germs of colds, grip, diphtheria, pneumonia and tuberculosis. It is probable that the avenues of transmission of these germs are limited as are those of the diseases already discovered. It is, therefore, much more difficult to demonstrate the exact part that any particular avenue plays in the transmission. That dirty money, which, according to Mr. Hilditch, of the Sheffield Laboratory, Dr. Park, of the Research Laboratory of the Board of Health of New York, found to be "similar to other paper and rags and capable of carrying living tubercle and diphtheria bacilli for some days or longer," plays an important and unfortunate part in such transmissions is not only highly probable but is rendered more so by the very conditions found by Mr. Hilditch on the twenty-four bills selected by him from various sources, none of which is known to have had any direct connection with infectious material.

Examinations of drinking water for the agents of cholera or typhoid infection is so laborious and negative results are of such uncertain value that bacteriologists do not ordinarily make use of the direct isolation and identification of the specific germs of the disease in determining the purity of a given water, but rather look for indirect evidence of pollution which may be determined with more certainty and which is accordingly of greater negative as well as positive value. This evidence ordinarily consists of the identification of the colon bacillus, the recognition of which is certain and the presence of which signifies the contamination of the drinking water with material in which the colon bacillus is a normal inhabitant, namely, with human or animal waste. The demonstration of colon bacilli, then, constitutes proof of pollution of the water in a way that makes the introduction of cholera and typhoid germs possible. Even if they are not present, the way is open for their introduction at any time and the water is accordingly unfit for consumption.

It is desirable, it seems to me, to apply precisely the same principles to money. Mr. Hilditch has demonstrated that the average number of bacteria in each of twenty-one bills was 142,000, while by far the most common forms present were the varieties of the pyogenic staphylococcus. These organisms were not in possession of their full virulence but merely produced a more or less local reaction, on guinea-pig injection, with swelling of the lymph glands of the groin. Their constant presence on money is certainly of greater significance than merely indicating the exposure to the bacterial contamination of the air; they clearly indicate that the money has been contaminated by handling and without regard to the virulence or the danger of infection to which these particular organisms themselves expose those who receive the money, they establish beyond question the most fundamental and significant fact for scientific demonstration, viz., that money is a medium of bacterial communication from one individual to another.

Upon the question of the communication of highly infectious organisms, scientific evidence should now be sought by competent examinations of money known to have been exposed to sources of such contamination. It is not enough to know that much of the money in circulation is merely dirty; it should be known whether it is or is not a medium of the transmission of disease where such disease exists to be transmitted. From the contributions of Mr. Hilditch it appears that the handling of money infects it; from the observations of Dr. Park it appears that the germs of diphtheria and tuberculosis may live on bills infected by these germs for several days or longer. It seems but a step, then, to the final demonstration of the actual transmission of these and similar diseases by money in circulation and to the prevention of such spread of disease by the proper measures to eradicate such possibilities.