LECTURE I.
*Read at the U. S. Naval War College in the Summer of I903.
Hygiene has many functions, being defined by various writers, writing at different periods of time, as signifying the prevention of disease and sickness; or as treating the actually sick by hygienic means rather than by drugs, such as constitutes, for instance, the present method of open-air treatment of consumption; or as the care of the well by the instruction of the people at large in the laws of hygienic living; or, finally, it is also spoken of as the science and art of raising the standard of human health, growth and development by all conceivable means, including systematic bathing and exercising the body as well as the mind, in strict accordance with the best principles prescribed by human physiology.
Like everything else, in these stirring times of universal progress, our conception of the term "hygiene" has gradually undergone a process of evolution and change; it has become more and more comprehensive as time went on. As our knowledge of and our experience with the subject increased from day to day, the depth and the extent of the meaning and significance of the term "hygiene" have deepened and widened correspondingly. Hygiene means all these things and more besides.
In some of my former lectures which I had the pleasure of giving at this college, I attempted to give a more or less systematic account of the elements of hygiene. My previous experience has convinced me that this would be impossible to do, even supposing I had eight or ten lecture hours at my disposal to do it in. In the two lectures which I have been requested to deliver before you this year, I have accordingly, and after duly considering the matter, concluded to select for a brief discussion with you a few of the more practical matters: fragments from the chapter of the "Prevention of the infectious diseases," choosing as types some of those that occur most frequently on board ships and with which you will all be sure to meet sooner or later.
In the choice of this subject, I have been directly influenced by some recent experience which went far to again impress upon me the importance as well as the necessity of the sympathetic cooperation between the commanding officer of a ship or station and his sanitary advisor, the surgeon, as a primary condition for the successful prevention not only of the introduction and spread of an infectious disease on board a ship or in a navy yard, but also for the more general purpose of maintaining a high standard of health in these places under all conditions, among the men under command.
The particular experience referred to was gained during my service as medical officer on board the Prairie, which vessel was four times threatened with an invasion of measles during the first twelve months, since last going into commission and which, moreover, only narrowly escaped from an epidemic of diphtheria last spring while undergoing a few minor repairs at the Norfolk navy yard. I hope to demonstrate to you that the cutting short of these several epidemics of measles as well as her escape from the diphtheria were entirely due to the cooperative action above referred to.
1. Measles on the Prairie.—The Prairie received her first complement of 450 landsmen for training from the U. S. R. S. Franklin about the 29th of December, 1901, and started immediately from Hampton Roads for the Gulf of Paria. On the second day out, two cases of measles appeared; two weeks later, seven cases of measles were admitted; two weeks from that time, four more cases of measles occurred. After this, the epidemic stopped. It is clear that out of these thirteen cases of measles, eleven were contracted on board ship from the two that came to us from the Franklin; it is also clear that the disease was quite ready to spread in geometric proportions, had it been allowed to do so. The second and third times measles came on board, it was arrested each single time, remaining confined to one case which was promptly recognized and sent to a hospital. On November 7, 1902, two days after the Prairie had left Norfolk with 500 marines on board and while on her way to Culebra, one case of measles was admitted; just fourteen days later three more cases appeared, after which the disease was again stamped out.
The first epidemic, then, ran its course in the Gulf of Paria, the last in Great Harbor, Culebra. The second and third attempts at invasion were met so promptly that they did not assume the epidemic form. It will be seen that three out of the four cases constituting the last epidemic were contracted on board from the one taken on board in Norfolk, and that this epidemic showed its readiness to progress as did the first epidemic—if left to itself, it would have spread until every susceptible person had been converted into an immune against measles. The object of our expedition, however, was not the immunizing of the men against measles but that of converting landsmen into ordinary seamen and every other aim had to be made subordinate to this chief object.
Measles being one of the most contagious of infectious diseases, and most of the Prairie's 720 men being still of a susceptible age, namely between 18 and 20 years, it is conceivable that a serious epidemic of them, under circumstances so favorable to the development and spread of them as they were on board the Prairie, would mean the temporary conversion of a training ship for landsmen into a hospital for contagious fevers, to the great loss in time and expense to the government and the naval service as well. It was, therefore, also reasonable to assume that any lesson we might have learned from actual experience in the past, any help we might get which would be calculated in the future to aid us in intercepting the onset, limiting the spread or impeding the progress of a disease of this character in any way under similar circumstances, would prove welcome and useful.
Suffice it to say right here and without mentioning many details in which my commanding officer seconded every effort I was concerned in making for the arrest of the epidemic, that nothing that could be done by him was left undone.
The reason that the first epidemic extended to thirteen cases probably was that it found us quite unprepared, being without a steam disinfector. 450 boys, quite unused to the sea together with the rather sudden transference from their native climate in midwinter to the Gulf of Paria, seemed to develop without warning all the weak points in their anatomy, so that the sick bay became crowded and isolation. (as that is generally understood on land) of those affected with any contagious disease was hardly to be thought of, much less to be carried out as it should be.
After having constructed a temporary sterilizer, the general principles of procedure were about as follows: The patient with measles was taken into the sick bay, made to step on a clean white sheet on which he dropped all his clothes. From here he went into a bath-tub where soap and water and the brush were used to scrub every square inch of his surface, including the hairy scalp, while the clothes he had left were wrapped up and put aside temporarily for future steam sterilization; after a patient had been scrubbed, he received a bichloride bath and after this, he was wrapped in a white sheet soaked in bichloride solution and put to bed. Three bichloride baths (sponge baths) were given him daily during the entire time of his sickness, his mouth and nose were rinsed four or five times daily with weak disinfecting solutions and he was supplied with gauze handkerchiefs soaked in the same solution, which he was ordered to use when he was either coughing or sneezing. The reasons for everything that was done were thoroughly explained to him. Any ear trouble, throat trouble or conjunctivitis were at once taken in hand and treated accordingly and while he was still in bed.
These are, in brief, the leading points of our treatment; the average duration of the cases treated on board was 8.56 days, counting from the day of admission to the day of discharge to duty, which is very good indeed and compares most favorably with the statistics of the disease. (Best results ever attained in the navy.)
You will see that the leading features in our method of handling the patients consisted in that most of the attention was directed to the patient himself as constituting the chief source of the danger of the spread of the disease; isolation, as was mentioned before, was impossible or, at best, could only partially be carried out and partial isolation is worse than none. Notwithstanding that no precautions other than those just described, were taken against the spread of the measles from one man to another in the sick bay, a measles patient often lying in a bunk adjoining that of a patient sick with quite a different disease, we are positively certain that no case of measles occurred that could be traced to any one of the patients after he had once been put under that treatment.
After a patient was well, his bichloride sheet was removed and he stepped into a clean and sterilized suit of clothes and at once went to duty.
Although I cannot go into details on the subject of an early diagnosis of the disease, I must, in fairness, mention the fact that without our having succeeded in establishing a diagnosis, on the average, two days before the eruption appeared, the number of cases would surely have been at least twice or three times as large, because it is known that patients attacked with this disease spread the contagion four or five days before the appearance of the eruption.
It is safe to say, even without referring to more accurate statistics on the matter, that measles, mumps, influenza, diphtheria and typhoid fever are the most common among the infectious diseases with which our ships are menaced, at least while cruising in home waters. All the receiving ships and naval stations had one or more epidemics. Some or all of these, usually, or of late years at any rate, have arrived on board the various receiving ships with the recruits sent there from all parts of the country by recruiting officers. Here, finding the conditions most favorable, they thrive and spread like bacteria in an incubator on a most favored medium and at the temperature optimum, before their existence is even suspected and the foundations for a long-continued and wide-spread epidemic are laid and must be the necessary consequence. The present receiving ships are generally over-crowded far beyond their allowable capacity and insanitary generally from various other reasons in addition (stagnant water); the number of medical officers on board is wholly inadequate, and the means at their disposal for combating such wholesale invasions wholly insufficient; hence their efforts are practically restricted to the sending of their patients to the hospital as they develop, which means, to a stage in the development of the epidemic when preventive measures are all but useless, because the germs of the disease are abroad and running wild, or, perhaps, are more carefully stored away in bags and hammocks, ready to be transferred to another ship whenever the time comes for a draft of men to be so shipped. Little wonder, therefore, that these receiving ships must be looked upon both as depots for the collection of all sorts of contagious diseases from all parts of the United States and as centers for the distribution of these diseases to the cruising ships of the navy. They are the veriest incubators for all sorts of disease-producing germs. The first in line to receive them are, very naturally, the training ships and from these, in due time, unless thoroughly stamped out there, they are transferred to the ships of the squadron.
In this simple manner whole fleets have been known to be invaded and measles, more especially in the past, have dragged along for months in a semi-epidemic form on board most, if not all, the different vessels of a fleet, half measures against them being ineffectual. A quarantine of at least two weeks should, in the future, be imposed upon all newly-arrived recruits and proper disinfecting plants be established to take care of their persons and clothing before they are allowed to join those already present.
Although it is never safe to generalize, each infectious disease being a law unto itself, needing different methods of handling in accordance with the difference in the character of the infectious germ causing the same, it is perhaps safe to say that the above described method would meet most of the requirements in the cases of scarlatina, rubeola, variola, variolois, varicella and exanthematic fever. All these diseases form a distinct group of infectious fevers having some very essential characteristics in common. They are all characterized by a peculiar skin eruption; they are all distinctly contagious and leave a rather enduring immunity. The germs causing them are still unknown and, from what we know of them so far, they cannot belong to the class of bacteria. It is highly probable that these germs infect the human organism by way of the mouth, throat and nose; it is certain that they cannot live long outside the living body, although remaining virulent for some time. Hence it results that in all this group of diseases, the chief danger from infection lies, first, in the infected patient himself and only in the second place in the persons and things with which he has been brought into immediate contact. Hence, also, the efficacy of the treatment above described.
Diphtheria.—There is, perhaps, not a single one of the disease-producing germs that have been discovered within recent years, better known than is the bacillus causing diphtheria. We may say that we know all about it except the chemical constitution of the poison which it produces and through which it effects all its mischief.
Being discovered by Klebs and Luffler just twenty years ago, Neisser has furnished us with a method of staining this bacillus by means of which we may sometimes diagnose a case of diphtheria even without the intervention of the usual culture, which latter delays the diagnosis at least 18 to 24 hours. By this method of double staining with methylene blue and Bismarck brown, we can stain the body of this little rod brown, and its ends a deep blue. Its favorite place is found in the mucous membranes, especially the human tonsils, where it forms a false grayish-white membrane and produces a poison which enters the blood, causing the disease; the bacillus rarely enters the blood-current bodily. The germ spreads most often from one individual to another. The opportunity is especially favorable, since the virulent germ resides often for months, even years, in the nose and throat of those who have been through an attack of this disease. Then again, experiments have shown that it remained virulent for a long time outside the human organism on the things that our patients have been in contact with. It is due to this particularly that the disease in some places remains epidemic the whole year round. We all know that, owing to the discovery of the antitoxin by Behring, diphtheria has lost most of its former death-dealing terror. Instead of our losing from 6o to 70 per cent of our diphtheria patients, as we did formerly, the timely and judicious use of this antitoxin has reduced this mortality to less than 10 per cent. When antitoxin is used on the first day of the disease, the death rate is from 1.07 to 2.7; when it is used on the second day, it has been found to be from 5.7 to 14.1 per cent; on the sixth day it rises to from 19.2 to 30.7 per cent.
Here there is a disease, one of the few of the infectious diseases against the ravages of which we can proceed with a specific remedy and ultimately cure it. In practical life, however, other conditions must be observed. Thus, diphtheria, having invaded a crowded ship, is still a very serious matter and one by no means to be taken lightly. Unless prompt and judicious measures are at once taken, diphtheria is as dangerous a disease as it ever was with all its former serious consequences. As is the case with every infectious disease, our means and methods of preventing its spread must be based upon an exact knowledge of the characters of the germ that produces the peculiar disease, if we wish to make no mistake and be successful in our efforts against it.
Assuming that the disease has become prevalent on board a ship, the first and most important step to be taken is to get rid of the chief danger, that is the patients themselves, all that belongs to them and everything with which they have lived in contact. This is, of course, possible only when communication with the shore can be established, namely, in home ports. The only after isolation has reference to surrounding every patient with such an armor as was described in our treatment for measles; which shall effectually prevent the escape of germs from his body and which I should attempt to carry out if caught at sea and away from shore communications. This, of course, presupposes our ability to diagnose every case on hand. Knowing, moreover, that the germ lives in and can be spread by the healthy, a certain percentage of whom are always found to harbor the germs during an epidemic, especially in crowded places such as ships, these must be found and treated accordingly. It seems evident that nothing short of a bacteriological examination of the throats and noses of every man of the ship's company, without exception, can effect this end. While those having the disease are sent to a hospital or otherwise isolated, the suspects or those bearing the germs without showing the actual symptoms of the disease, must be temporarily quarantined in a special tent, or if that cannot be done, their throats and noses treated with weak disinfectant solutions, their clothes disinfected and all avoidable communication forbidden. Their mess gear must be kept separate from that of the rest. Those remaining on board in active duty must be kept under constant guard, every simple case of tonsillitis at once examined for bacteria and, if any are found, separated from the well and clean.
There is no time that can be called too soon when the injection of antitoxin is commenced; the sick as well as the sound must receive it. An ordinary preventive dose for the well is, of course, much smaller than that to be administered to the sick; one dose of 200 immunizing units is sufficient for the well and will surely prevent the disease. In the case of those already showing signs and symptoms of the disease, the number of units to be administered must depend upon the severity of the course of the disease and be left to the judgment of the physician in any case—1000, 2000, 3000 units.
Of course, the old adage, of an ounce of prevention being better than a pound of cure, never shows itself as true as it does in the case of our struggles against the spread of an infectious disease. But it is just here, in these early attempts at keeping the disease away from his ship and at a time when the danger seems as yet far off to those unacquainted with the characters of disease-producing germs, that the surgeon meets with the greatest difficulties. Only too often, his suggestions and remonstrances are pronounced too severe, unreasonable and altogether impracticable and unnecessary. And yet they may mean just that ounce of prevention we have spoken of. During an epidemic, a certain number of cases of simple tonsillitis occurred on board the Prairie, due to streptococcus invasions. During that month we had between thirty and forty such cases. Daily examinations of the throats and noses, with the microscope for the diphtheritic bacilli were made and, in the doubtful cases, cultures were employed. Cultures of some cases were also sent to the hospital for the confirmation of our own examinations. I am now happy to state that of all the cases examined, not one case was discovered, in which the true bacillus of diphtheria was found and we had, by a careful and thorough quarantine, kept the disease out of the Prairie.
The time came when our repairs at the yard were completed and we were ready to receive 350 landsmen from the receiving ships. I had the assurance of Dr. Berryhill, who had been ordered there for the purpose of stamping out the epidemic and done excellent work, that the men we were to receive had satisfied all the requirements of people free from the disease, and we took them on board. Upon examining the newly-arrived lot of landsmen, three men were found among them who had not left the ship during the time measures for prevention had been taken. Neither had their persons ever been examined nor their package cleaned and disinfected. I recommended that they be returned at once. The commanding officer of the receiving 'ship refused to accept them unless on order from the commandant of the station could be obtained.
These three men broke the chain of the whole process of weeding out the well from the sick, the safe from the dangerous ones. A thorough appreciation of the principles involved, of the absolute necessity of observing all the details in the process, in order to insure success and not to destroy all previous efforts, and waste all the expense involved so far, could not have permitted these three men to have come within ten yards of those put through the required process. This technical mistake, if allowed to prevail, would almost surely have resulted in transferring the disease to a healthy ship of 720 men, ready to start a fresh epidemic, with all the necessary consequences in its wake.
Fortunately, such an order from the commandant was produced, the three men were returned and the Prairie remained free from diphtheria in consequence.
Mumps.—Mumps is another of those infectious diseases that frequently visit ships and stay a long time and the causative agent of which remains as yet entirely unknown. The objection to mumps is that they drag along for months and years on board ships, especially when they are cruising in foreign waters, and single cases cannot be sent to a naval hospital the moment they occur. Although this disease is not of a dangerous character, beyond that the service loses a good many working days, it causes in one-third of the cases a permanent atrophy of either one or both testicles, resulting in sterility.
The germ, whether a protozoon or a bacterium has a special liking for the parotid and sometimes also the other salivary glands and causes them to swell up. The great tenacity of its epidemic character is most probably due to the long period of incubation, which is eighteen days; the disease itself lasting about ten days on the average.
The germ being unknown, it is of course impossible to say I through what particular channels it leaves the infected persons, so that we are not exactly certain in what direction we are to direct our efforts at the prevention of the spread of the disease. But, knowing that the germs principally affect the salivary glands which discharge all their secretions into the cavity of the mouth, it is most likely that it will be there that the germs will some day be discovered when some one shall invent a method of staining that shall enable us to recognize them. To the expectoration, therefore, must be directed our principal efforts at preventing its spread. Indeed, the Italian naval surgeon, Belli, tells us that mumps on board the Varesi, an Italian second-class battleship, did not cease to be epidemic until all the spittoons had been thoroughly disinfected and until a heavy penalty had been put upon the promiscuous spitting on the decks.
In this connection it certainly is interesting to read what Surgeon Charles F. Stokes has to say in his last report to the Surgeon General with regard to the cup at the scuttle-butt. He says:
"The importance of providing the ship's company with distilled water is now thoroughly established and appreciated, but the sanitary importance of the scuttle-butt cup appears to have been overlooked.
"This cup, as a disease spreader, is ideal. A member of the ship's company with an infective disease drinks at the scuttle-butt, leaving some of the secretions of his mouth, germ-laden, on the lip of the cup, and the next man, possibly awaiting his turn, gets an undiluted virulent culture of the organism from the outside and edge of the cup rim. On this ship the drinking cups in use by the men are kept submerged in a solution of formaldehyde (1-2500), and outbreaks of tonsillitis, mumps, grippe, etc., have been checked in this way."
I have for many years insisted upon frequent rinsing out of the mouth with weak disinfecting solutions and receiving all expectorated matters in antiseptic spittoons or into a bichloride handkerchief which was afterwards burned or thrown overboard. This treatment was strictly followed out on board the Prairie Where we had two cases about a year ago, and to these two cases the epidemic remained confined and did not spread.
Here also, however, we must not underestimate the preventive value of an early diagnosis and consequent isolation of the patient. Owing to the long period of incubation peculiar to mumps, a man may, for twenty days, expectorate in every part of the ship and, adding to this a moist climate and a hot ship, all conditions under which any germ must flourish, a long continued epidemic may have been started before even the first case comes to be noted.
Tuberculosis.—The literature on tuberculosis is so vast and the cause of the disease so widely known that I shall confine myself to only a few remarks with regard to the most recent experiments made, with the object of showing that the expectoration of the tuberculous patient is the most frequent and effectual source of the transmission of the disease from one individual to another. It has been found by a number of the most painstaking experimenters in Germany that the spray, sent into the atmosphere during the acts of coughing and sneezing, sends the tubercle bacilli not only in a direction right in front of the person coughing but likewise in the rear of him.
Observations as regards the time during which these fine little particles of spray, carrying the bacilli with them, remain afloat in the air, show that they are exceedingly light, since they have been found to remain suspended for hours.
It has recently been found, moreover, that tuberculosis is much more often transmitted through such spray than through the dried dust that rises into the atmosphere from sweeping. The spray is richer in the number and virulence of its germs than the dust collected in the rooms of tuberculous patients. Under normal conditions, the spray from a tuberculous patient while coughing in a room is carried a distance in front of him of about one meter; hence such a distance is considered as the danger zone. From these few facts alone, the means and methods that naturally suggest themselves as applicable to the prevention of the disease on board ship are self-evident. The crowded conditions under which the men are living on board ship, being rarely more than one meter apart whether they are working on deck or in the engine- or fire-room, or whether they are asleep in their hammocks, would seem to make it imperative to send tuberculous patients out of the ship as soon as they are so diagnosed. This is not inhuman but rather as much to the interest of the patient himself as it is for the protection of the ship's company.
Fortunately, a diagnosis can readily be made and the tubercle bacillus is recognized under the microscope with the greatest of ease.
In this lecture, as you have seen, I have touched upon some of the more common domestic infectious diseases and the principles of their prevention; in my next lecture I shall take up the two most important tropical types of disease, namely: malaria and yellow fever.
LECTURE II.
Malaria.—There is perhaps no known infectious disease that has received so much attention of late as has malaria. The whole history of medicine knows no parallel. Upwards of 5000 books, monographs and pamphlets have, within the last three years, been published on malaria alone, not to speak of the large number of government reports, not in the open market, that have been made by a large number of commissions, sent out to all parts of the tropical world by the governments of Europe, with the object of investigating this disease and, if possible, of devising means for its extermination. This wide-spread attack upon malaria has been caused less by motives of humanity than by the interests of European nations in the colonization and civilization of those rich tropical countries. The object of making these countries give up their treasures, or cause them to yield agricultural products of still more value and use to the civilized world, than gold and other minerals, it seems, can never be attained unless it can be shown that malaria can be stamped out. The very question of the existence and of the permanent settlement of the white man in these tropical climes seems, at present, to revolve around the question of the exterminability of malarial disease.
The United States, besides having malaria within its own borders, has large interests vested in tropical climates; her ships have frequently been visited by the disease and many of the officers and men in the navy have suffered from its consequences.
The history of malaria practically began with the discovery of the medicinal virtues resident in the Peruvian bark, by the Countess Cinchon, then wife of the viceroy of Peru, in 1640. The next important event occurred in November, 1880, when Dr. Laveran, a French army surgeon, for the first time saw the malarial parasite in the blood of a patient suffering from malarial fever. In 1885, an Italian physician, Golgi, studied and described for the first time the different stages of development of the parasite in human blood. In 1898, the English army surgeon, Ross, proved the transmissibility of the malarial parasite through the mosquito, and since that time a whole army corps of investigators have contributed many valuable facts regarding malaria, its cure and prevention. These are, briefly stated, the most important events in the history of malaria.
The fact that, during the last International Medical Congress at Madrid, a unanimous vote of thanks was telegraphed to Laveran, Baccelli, Koch, Ross, Manson and Grassi, must be considered as proof sufficient that the discoveries of these men regarding malaria have met with the most general and world-wide acceptance and recognition.
The peculiar parasite which, when it finds entrance into the human organism, causes what is known as malaria or intermittent fever, is a protozoon, resembling in its characters those forming the class of coccidia. The malarial parasite, however, differs from the family of the coccidia, in that it is parasitic from the start and lives exclusively on the red blood-corpuscles, while the coccidian are parasitic only to epithelial cells.
The parasite passes through two different forms of development; one in human blood (endogenous) and another within the body of the Anopheles mosquito (exogenous). Since a knowledge of these two developmental cycles will greatly assist in an intelligent appreciation of the epidemiology of malaria, we will follow the parasite step by step with the aid of the figures on the adjoining plate. Fig. 1 shows a red blood-corpuscle into which one of the parasites is boring its way, having been put there by the proboscis of a mosquito; Fig. 2 shows that the parasite has grown at the expense of the blood-cell; in Fig. 3 we notice that the parasite has divided into a number of small parasites, still within the blood-cell; in Fig. 4 the blood-cell has been destroyed, the small parasites have been set free. Two ways are now open for the parasites to pursue: one is that they reenter a blood-cell and repeat the same development over again; another is that they develop into sexual forms as shown in Figs. 5, 6, 7b and 7a. Fig. 7b shows a female parasite, and Fig. 7a a male parasite. So far the development is called asexual or schizogonic, man being only the intermediate host of the parasite, not the real one. If now some of the blood, containing these sexual forms, gets into the stomach of the mosquito, the further development of these forms is completed; Fig. 8b shows a completely developed female parasite, while 8a shows a male parasite in the same advanced stage of development. In Fig. 9 we see the spermatozoa leaving the male parasite and making for the female parasite, shown in Fig. 10. Fig. 11 shows the parasite in the worm-like stage in which it bores its way through the coat of the stomach and becomes encysted just beneath its peritoneal covering. Here begins the spore-formation (13) which is continued into the development of the final sickle-shaped parasites (14) which burst the capsule, drop into the body-fluids of the mosquito and thus find their way into the proboscis or stinger of the insect and thence again into the blood of man. This last form of development is the sexual or sporogonic form of development of the malarial parasite. These two forms of development must alternate with one another, if the parasite is to continue to flourish. The schizogonic development is limited and must ultimately end with the death of the parasite unless complemented by the sporogonic form of development. It has, however, quite recently been discovered that the arrested form of the parasite in human blood (Figs. 5 and 6), called gamete, may revert to the schizogonic form of development under certain conditions, and this is really what occurs when malarial attacks recur without actual infection by fresh infected mosquitoes. The morphological proof of this has recently been furnished us by Schaudinn.
Human malarial parasites are at present classified into two distinct varieties:
1. Large Parasites, divided into:
a. The tertian (Haemamoeba vivax.)
b. The quartan (Haemamoeba Laverani.)
2. The small ring-shaped parasites, which have received many different names.
1. The large parasites: a. Tertian.
If you take a drop of blood from a malarial patient during the time the temperature is going down and put it under a good microscope, you will find in or upon the surface of the red blood corpuscles the earliest or youngest as well as the smallest forms of the tertian parasites. In size they are about one-sixth the diameter of the red blood-corpuscle. If you will stain a thin film of such blood on a thin cover-glass, you will see small rings, the outlines of which are stained sky-blue, with a blood-red, compact, little spot in some part of the ring, looking in fact like a seal ring. Twenty-four hours after the chill, these rings will be found much larger and show small, black masses of pigment in the center. Often, the parasite will not assume the ring shape, looking more like an amoeba that had become solidified the moment it had just stretched out its numerous arms.
Thirty-six hours after the chill, not a single ring-form is to be seen; the parasites, which now nearly, but not quite, fill the entire red corpuscle, appear as blue discs containing lots of pigment. The red corpuscles are now twice their normal size and have become very pale.
At last, just before the next chill is due, the parasites show signs of division or sporulation. The corpuscle, now entirely filled with these spore-like organisms, suddenly bursts, setting them free. They now are ready and in a condition to invade fresh blood corpuscles, while the black pigment is swallowed up by the white corpuscles. These forms that have been mentioned so far are the asexual forms or schizonts.
After a patient has had several attacks of fever there are in the blood certain other forms of parasites, in which the pigment is scattered uniformly through the entire disc. They either fill out the entire corpuscle or are free. No signs of division are seen. These are the spheres or gametes. A patient may have these in his blood for many days and no chill need occur. (Occasionally dumb chills are complained of.)
The Quartan Parasite is distinguished from the tertian in that it never exceeds the size of the red corpuscle, and the blood corpuscle itself is never enlarged nor loses its normal color. The development is similar to that of the tertian, only it lasts seventy-two instead of forty-eight hours; it is less stormy than the tertian.
3. The small parasites of Tropical Malaria.
These appear different from either the Benign Tertian or the Quartan. The blood, during the time the fever is at its height, just shows the smallest and finest rings, so sharp that they look as if drawn with a pen. Their diameter is about one-fifth that of a red blood-corpuscle. These are called the small tropical rings. They grow larger as they grow older, but even the largest never attain more than one-third the diameter of red blood-corpuscle. There are other characteristics by which the tropical parasites can be distinguished from the large parasites, but these we need not go into in this connection. Suffice it to say that we can, with some practice, easily distinguish these three different forms of parasites. (Marines at San Juan.)
The mere idea that mosquitoes could transfer malaria is not new. It had been frequently brought forward, but no one had been able to prove it. It was in 1897 when Ross succeeded in cultivating, as it were, the human parasite in the bodies of certain species of mosquito. In 1898, he, moreover, succeeded in transferring the disease to healthy birds, thus completing the entire circle of proof. Every investigator has since confirmed Ross's researches. The fact that the Anopheles mosquito is the only Species of mosquito so far discovered that transmits human malaria, was established by Koch. Bird malaria—due to Halteridium and Proteosoma—is harmless to men.
A few remarks on these two kinds of mosquito, the common culex and the anopheles, would seem necessary, in order the better to understand the principles involved in their destruction, which latter forms one of the chief methods of attack against the disease.
These differences, indeed, begin very early, namely, with the laying of the eggs. While the culecida lay their eggs in little heaps upon the water, the anopheles lay theirs more in the form of a thin film. The larva of the culicida hang vertically from the surface, head down, while the larva of the anopheles have their bodies parallel to the surface of the water.
The anopheles larva prefer small pools of water containing an abundance of alga, well protected from the wind and situated in shady places. The culex larva is less particular in this respect, and any little pool of water anywhere, tin cans, barrels, the bot toms of small boats, will satisfy her. Running water is free from larvae. The larva becomes the pupa, also living in the water, and from the pupa the winged insect is finally developed.
The female of the culex is easily distinguished by the small head and its long stinger. This is usually kept covered by a sheath; on either side of the stinger, a hollow needle, are the two very short palps, and outside of these are the antennae or feelers. The thorax is connected with the head by a thin neck, and is succeeded by the worm-like body. The two wings show very intricate venations which are used to distinguish the different species and varieties.
The gunus anopheles is distinguished from the culex by the palps, which are nearly as long as the stinger in both sexes. The male has feathered antennae.
You can at once distinguish a culex from an anopheles by the position which they assume on the wall. The body of the culex is nearly parallel with the surface of the wall, while the body of the anopheles forms an angle of 1450 to the surface. A few facts about them are:
I. The females alone suck blood, the males live on a vegetable diet.
II. They are night wanderers.
III. During the day they hide in the grass, on the under surface of leaves or in the bark of trees, protected from wind.
IV. Fertilized females hibernate in towns and come out in February or March. The males die. The females prefer human habitations and suck blood as soon as they can, for only after they have done so do they develop their fertilized eggs.
V. Females do not die, as is commonly thought, after sucking blood but live on to go through that process several times.
The examination of the mosquitoes, the work of dissecting out the salivary gland and looking for the germs is a tedious and very delicate sort of work which we need not go into.
EPIDEMIOLOGY.—The cause of malaria had previously been placed in the soil, because turning over the soil had always been followed by an increased morbidity. When it was shown that the soil theory did not explain half the facts connected with the epidemiology of the disease, it was located in the water; this theory also proved only half right, explained only a few known facts.
Now the question is, does the mosquito theory agree with all the facts known with regard to the epidemiology of malaria?
When we go through it, item by item, you will see that the mosquito theory agrees with everything connected with malaria, and leaves absolutely nothing unexplained.
1. It had long been known that malarial fevers appeared about twenty-one days after a temperature maximum had been reached that did not sink below 24° C., 75° F. in the houses. The anopheles must be kept steadily at that temperature if the malarial germ is expected to develop in them. If we allow ten days for the development of the parasite in the body of the mosquito and ten to eleven days for the period of incubation, the appearance of malaria, twenty-one days after the temperature maximum has appeared, is sufficiently explained. The rapidity of the development, however, is known to depend on the temperature, and can be accomplished in less time if it is higher; at 27° C. the development of the malaria germ in the body of the mosquito is completed in nine days and the remainder of the latent period is filled out by the period of incubation.
2. Malarial infection occurs for the most part during the night. The anopheles is a night wanderer and stings during the day only when stirred up in its hiding place.
3. Malaria is a disease of the country, and not so much of cities, because the anopheles finds no breeding places in cities and plenty of them in the open country.
4. Continued building and cultivating a soil gradually lead to the extinction of malaria, because they deprive the anopheles of its breeding places.
5. Merely turning over the soil always is succeeded by malarial disease. The anopheles leaves its place of hiding and stings the laborer; new pools are created in which they deposit their eggs, from which within 12 days new mosquitoes develop.
6. When in northern countries malarial fevers have decreased, it is principally to be attributed to the judicious administration of quinine. The parasites being killed, the mosquitoes were unable to infect themselves.
Men on board ship—provided the ship is anchored a certain distance from the shore—suffer much less from malarial infection as long as they remain on board than the people on land, because the anopheles does not fly great distances and only a few specimens are but occasionally found on board. The flight of the anopheles, the farthest ever known, is 5 km., or 2.2 miles.
Another fact is for the first time well explained, namely: in the tropics it is the transitional periods, both between the dry and the wet season as well as between the wet and the dry season, which always mark the greatest malarial development. It is the small and infrequent rains which cause many small pools in which the mosquito larvae can complete their development before they are disturbed; while frequent and large rains flood and destroy their breeding places.
We know, moreover, while the anopheles stings all the year around it does not infect all the year around. During the time it is non-infectious, the malaria germ is not developed on account of the absence of the proper temperature. In the spring when it becomes infected and finds the conditions more favorable, the germs develop and then the mosquitoes carry the disease.
Hence the recommendation of R. Koch to kill the germs that are in the blood of those suffering from chronic malaria before the time mosquitoes become plenty, and thus break the chain of communication by systematic administration of quinine.
PREVENTION OF MALARIA. a. Personal.—The chief aim of the personal prevention of malaria consists in taking preventive doses of quinine before infection is carried so far as to bring on an attack of the fever.
Dr. Robert Koch recently, during his travels in the tropics, has interested himself in this problem and has come to the conclusion that quinine in a single dose cannot be relied upon to prevent malaria. He found, on the contrary, that two doses on successive days were necessary to do that. His rule is to give fifteen grains of the drug every tenth and eleventh day in the morning; in case of fever occurring in spite of this, he either increases the dose to 1.5 grams or gives the same dose every ninth and tenth day. As a rule, the stomach bears such a dose without disturbance.
Another method was employed by Plehn in East Africa: Seven grains of quinine were given every fifth and sixth day, instead of, as had been proposed by Koch, fifteen grains every tenth and eleventh day. This plan, in almost everyone's hands, has failed to prevent the fever, in spite of the fact that the total amount of the drug administered was the same, although given at more frequent intervals. The taking of quinine in the above prophylactic doses seems to be the only means so far known by which the fever is prevented. Such doses must be given to those who have had the fever, no matter whether it was the tropical form or the more benign northern type of the disease, if they are to have no return of the trouble. Even if patients return to a northern climate, this preventive dose of quinine given every nine and ten days must be continued for at least three months if returns of chills are to be prevented.
Every other means that has been employed for the prevention of the fever, when compared in its effects to those of quinine, is of minor importance and of secondary value.
Next to quinine, the mosquito net is coming more and more to the front, not alone because it prevents infection but also because an undisturbed sleep in the tropics is of much greater importance than it is in a temperate climate. Fires in front of the tent during the night are also very effectual in attracting and finally burning the mosquitoes.
Mosquito-proof houses in the tropics are still in the experimental stage. Their usefulness is undoubted but the practical requirements on man, to expose himself, even after sundown, to the stings of mosquitoes, render these houses of no use, after the men living in them have thus become infected. All houses in the tropics offer to the mosquitoes hiding places, and of the mosquitoes found in the houses of the natives especially, 50% are found to be infected with the malarial germs, while of those in the open air but 5% are malarial. These native huts form, therefore, the greatest danger to the white man; hence their quarters are built preferably away from native habitations. The best and safest personal prophylaxis, therefore, remains the administration of quinine in proper doses and at proper time intervals.
a. General prophylaxis.—The belief was entertained that malaria could be prevented by the extermination of the mosquito. If this will be found possible, malarial fever, undoubtedly, must some day disappear. So far, however, this possibility must be doubted. Both the attacks upon the full-grown mosquito and those made upon its larvae have had but temporary results.
Petroleum and lime have been put into the small pools of water in marshy districts of Africa every other day for a period of three months, and the effect produced within a limited geographical area, though quite perceptible, was but temporary.
Since, as we have seen, neither the generalization of the personal quinine prophylaxis in tropical countries, nor the attempts at the destruction of the mosquito on a large scale, have been absolutely and invariably successful in ridding a country of malarial disease, Koch has proposed a new plan of campaign. R. Koch assumes that malaria, like the plague and cholera and diphtheria, could only be successfully attacked by a careful search after light cases, such as do not usually come to the notice of the physician and pass on, spreading the disease unobserved, while themselves showing no symptoms of it. These light cases must be found and cured if the work is to be thorough. This principle was strictly carried out by Koch in Stephansort, New Guinea. A systematic blood examination of all the inhabitants of the place was made and all the cases proving of malarious nature, showed the parasites in their blood, and were treated with quinine. In this manner he succeeded in rendering the place absolutely free from malaria, and at the same time, all the recurrent cases were thus prevented. Koch's plan was strictly carried out during the building of docks in Wilhelmshafen, Germany, in 1901. Dr Martini, staff surgeon in His Majesty's Navy, reports to the German Colonial Congress in 1902 that, owing to this method of procedure, the morbidity due to malaria had been quickly reduced from 200% to 0.5%; a most excellent result, showing not only what can be done by this method but also the unceasing search for malarial germs that must have been made in order to accomplish it. These are, indeed, the best results with which the prophylaxis of malarial fever has ever been attended, and these principles of prevention would no doubt be adopted and strictly carried out on a large scale in case the United States should ever build the canal on the Isthmus or at Nicaragua. The success of the plan will depend much more on the thoroughness with which it is done than upon the plan itself. Mosquito-proof tents will always be used. This plan of making frequent blood examinations, administering prophylactic doses of quinine on the slightest suspicion, was also carried out on board the Prairie while in Culebra, so far as the ship's company was concerned, and no fresh case developed, although our ship was anchored well within the zone of flight of the small anopheles mosquito. The only cases that did occur were in three officers to whom prophylactic doses of quinine had not been administered, nor had blood examinations been made. These were all recurrent cases and not due to fresh infection contracted at Culebra.
Yellow Fever.-It seems but a very short time since we stood in helpless ignorance facing the question of the prevention and spread of this dreaded disease. The numerous attempts that had been made by Sternberg, Sanarelli and others to discover the yellow fever germ had all been inconclusive. This germ still remains to be discovered. About twenty years ago, the idea that yellow fever was spread by the mosquito had been expressed by Dr. Carlos Finlay; it had, however, remained unproven.
In 1900, by a very carefully planned series of experiments by Drs. Reed and Carroll, it was shown for the first time conclusively that yellow fever was spread by the mosquito. These experiments were so planned and carried out with such scientific accuracy that the results attained proved absolutely convincing, and there is now no longer any doubt as to the correctness of the conclusions reached by these experimenters. The experiments were practically repeated and confirmed in toto by an English commission, sent to Brazil from the School of Tropical Medicine at Liverpool, consisting of Drs. Durham and Meyers, the latter dying of the disease, the former contracting it without dying, during the experiments they were making at Para.
During the American occupation of Cuba, the following precautions were taken for the suppression of yellow fever in Havana: as soon as a yellow fever case was reported, the house in which it had occurred was placed under quarantine. Reliable guards were placed around it, whose duty it was to see that no one but the attending physicians were allowed to pass in or out.
When, in 1901, the theory, that yellow fever was carried by the mosquito alone, was proven by Dr. Reed and accepted by the Board of Health, the method of procedure against the spread of the disease was modified as follows: The infected house was covered in by canvas, at public expense, every crevice was caulked in order that no mosquito should have a chance either to escape or to enter the place. After the patient had either recovered or died, the house was fumigated by the burning of insect powder; the clothes were left untouched. Since the germ could only be conveyed through the stings of the living mosquito, it was, of course, furthermore to be assumed that it could not exist outside either the human body or that of the mosquito; its very existence was made conditional upon this, hence the clothes and other things that yellow fever patients had come in contact with must be harmless, in accordance with the newly accepted theory, and this indeed proved to be the case.
Since it was found, upon further investigation, that almost all the small towns of Cuba were infected and that they were a constant danger to the city of Havana from immigration, all the physicians of these towns were ordered to notify the sanitary authorities of Havana by telegraph in case any one left there for Havana and to give their names. On the arrival of such a person at Havana, his place of residence during his stay was noted by the official who had met the man. A physician visited the house once in twenty-four hours, examining the suspect as to his temperature. In case he was not there at the appointed time and could not be found, a mild punishment was administered. This seemed to be sufficient to ensure good results.
The success of these measures was surprisingly good. Up to the end of the first year, 1250 non-immunes had been reported; of this number, the fever was almost at once discovered in twenty-seven cases. From May until July, for the first time in 150 years, Havana remained free from yellow fever. This was certainly a most unexpected and surprisingly good result in a city of 275,000 inhabitants and which was considered as thoroughly and permanently infected. The very success which had attended these preventive measures, all based upon the mosquito theory of yellow fever and carried out in strict accordance with its provisions furnishes the long missing link in the chain of proof. It may now be taken as sufficiently well established to serve as a working basis for all future attempts at the prevention of the spread and propagation of yellow fever.
The methods of both the propagation and the prevention of yellow fever are so similar to those of malarial fevers that there can scarcely be any doubt left of the fact that its germ, which will before long be discovered, will prove to be a protozoon, similar to the germ of malaria, and not a bacterium. The principles of the prevention of yellow fever on board ship, therefore, are, as a consequence, almost identical with those that are followed out in the case of the malarial fevers, except we have as yet no specific like quinine for yellow fever. We must, in some way, break the double cycle necessary for the development in the mosquito of both malaria and yellow fever germs, to prevent a successful infection of man by the fully developed germ.
How tenaciously yellow fever sometimes clings to ships, you all know from your own experience. Ships have been kept at freezing temperatures a whole winter; they have, in addition been repeatedly—and according to reports—thoroughly disinfected, and yet yellow fever has continued in them undiminished. Recently it has been proposed to burn pyrethrum powder in ships infected with yellow fever, because the fumes of this powder render the mosquito senseless. It falls on the deck, stunned, and, before it recovers, is swept up and killed. But whoever has once tried to find and catch the small stegomyia, has also found out that it hides in the most impossible places; so that it might be asked: what becomes of those mosquitoes which are in hiding during the process of such fumigation and which do not fall on deck; (Mense) do they not recover and go on with their work?
Mosquitoes prefer to hide during the day in dark and poorly ventilated places like the orlop, which is an ideal breeding place for them, and many cases of mild forms of yellow fever have occurred in men sleeping in the orlop of an infected ship, or some Other place excluded from the general ventilating system. The diagnosis in many instances has either been wrong or, for reasons of convenience, the truth about it has been known and intentionally suppressed. A most pernicious practice.
The disinfection of a ship infected with yellow fever, to deserve the adjective "thorough" must kill every one of the mosquitoes present anywhere in that ship. The stegomyia being a night wanderer, such disinfection at any rate had better be undertaken during the night or at a time when it is not in hiding.
As an example of day-disinfection and the inefficiency of it, the following most recent instance may be quoted: A steamer arrived in New York from Progreso after a six weeks' passage with a yellow fever patient on board. The patient died in the harbor, and—so the report says—the ship was thoroughly disinfected. Apparently clean, the steamer proceeded from New York to Jacksonville. The captain's wife took sick on the way and died at Jacksonville. The ship left for Santiago, and, during a voyage of six days, three more cases developed, of whom one man died. At Santiago the whole ship's company was landed and sent to a hospital where eight more cases occurred. The stegomyia would have completed its deadly work by killing everyone on board had it been allowed to do so, in spite of the last thorough disinfection at New York.
In my opinion, any mention of this most important and now most generally accepted result regarding yellow fever, its causation by infected mosquitoes and methods of prevention by Drs. Reed, Carroll, Agramonte, Lazear and Major Gorgas of the army, without its referring to the cooperative support which these medical men received from General Wood in every way within his power, would indeed be ungrateful as well as incomplete. The magnitude and far-reaching importance of the discovery, its everlasting benefits to mankind, coupled with the fact that it would not and could not have been accomplished without the moral, physical and financial support and the intelligent cooperation of the then Commanding General of Cuba, entitles him to a large share of the credit in this great achievement.