a community,' and is increased in the bodies of those whom it attacks, indicates that the two agencies of yellow fever and paroxysmal fevers are entirely distinct." That great point being considered settled, the inquiry into the conditions of the spread of yellow fever becomes easier. The points to seize are its frequent and regular localization and its transportation. The localization at once disconnects it from any general atmospheric wave of poison; it is no doubt greatly influenced by temperature, and is worse when the temperature is above 70° Fahr. Though it will continue to spread in a colder air than was formerly supposed, it does not spread rapidly, and appears to die out; but even temperature does not cause it to become general in a place. The localizing causes are evidently (cases of Lisbon, Gibraltar, West Indies, etc.) connected with accumulation of excreta round dwellings, and overcrowding. Of the former there are abundant instances, and it is now coming out more and more clearly that, to use a convenient phrase, yellow fever, like cholera and typhoid fever, is a fecal disease. And here we find the explanation of its localization in the West Indian barracks in the olden time. Round every barrack there were cesspits, often open to sun and air. Every evacuation of healthy and sick men was thrown into perhaps the same places. Grant that yellow fever was somehow or other introduced, and let us assume (what is highly probable) that the vomited and fecal matters spread the disease, and it is evident why, in St. James' Barracks at Trinidad, or St. Ann's Barracks at Barbadoes, men were dying by dozens, while at a little distance there was no disease. The prevalence on board ship is as easily explained. Granted that yellow fever is once imported into the ship, then the conditions of spread are probably as favorable as in the most crowded city; planks and cots get impregnated with the discharges, which may even find their way into the hold and bilge. No one who knows how difficult it is to help such impregnation in the best hospitals on shore, and who remembers the imperfect arrangements on board ship for sickness, will doubt this. Then, in many ships, indeed in almost all in unequal degrees, ventilation is most imperfect, and the air is never cleansed. Overcrowding, and what is equivalent, defective ventilation, is another great auxiliary; and Bone' relates several striking instances.* I Cases of the Bann, Eclair, Icarus, and several others. The remarkable introduction of yellow fever from Havana into St. Nazaire, in France (near Brest), is most striking, and cannot be explained away. It spread both from the ship, and, in one instance, from persons. (See Aitken's Medicine, 7th edit., 1880; and Report on Hygiene for 1862, in the Army Medical Report, by Dr. Parkes.) The introduction into Rio in 1849, and into Monte Video, are still more striking cases of importation; and a case very similar to that of St. Nazaire occurred some years ago at Swansea. (See Report (by Dr. Buchanan) to the Medical Officer of the Privy Council, 1866.) * As more care is taken, the symptoms of the two diseases also are found to be diagnostic, and if it were not for the constant use of the unhappy term "remittent," the confusion would not have so long prevailed. An interesting instance of good diagnosis was made by the French at Vera Cruz in 1861. In the spring the vomito prevailed, and then disappeared. Some months afterward, cases of a disease occurred so like yellow fever that they were at first taken to be that disease, but on a closer examination they were found to be clearly paroxysmal, and to yield to quinine.-Rec. de Mem. de Méd. Milit., 1863. * Yellow Fever, by G. F. Bone, Assistant Surgeon to the Forces. For example, in the same barrack, the windward rooms have been quite healthy, and the leeward rooms attacked. Men in the latter have ceased to have cases of the disease when moved to the former locality. (See a good case in Bone, op. cit., p. 13.) The question of the origin of yellow fever is one which cannot be considered in this work, and at present no preventive rules of importance can be drawn from the discussion. The chief preventive measures for the external cause are these:— 1. The portability being proved, the greatest care should be taken to prevent introduction, either by sick men, or by men who have left an infected ship. The case of the Anne Marie' has made it quite uncertain what period of time should have elapsed before an infected ship can be considered safe; in fact, it probably cannot be safe until the cargo has been discharged and the ship thoroughly cleansed. Still, it appears, that if men leaving an infected place or ship pass into places well ventilated and in fair sanitary condition, they seldom carry the disease; in other words, the disease is seldom portable by men, but it will occur. It appears necessary, also, to consider that the incubative period is longer than usually supposed, probably often fourteen or sixteen days. In the case of a ship, it seems desirable not to consider danger over until at least twenty days have elapsed since the cure or death of the last case, and even at that time to thoroughly fumigate the ship with chlorine and nitrous acid before the cargo is touched. Men working on board such a ship should work by relays, so as not to be more than an hour at a time in the hold.' In case men sick with yellow fever must be received into a barrack or hospital, they should be isolated, placed in the best ventilated rooms at the top of the house, if possible, or, better still, in separate houses, and all discharges mixed with zinc sulphate and zinc chloride, and separately disposed of, and not allowed to pass into any closet or latrine. 2. The introduction by drinking-water not being disproved, care should be taken that the possibility of this mode of introduction be not overlooked. 3. Perfect sewerage and ventilation of any station would probably in great measure preserve from yellow fever, but in addition, in the yellow fever zone, elevation is said to have a very great effect, though the confusion between malarious fevers and the vomito renders the evidence on this point less certain, and its introduction into Newcastle in Jamaica (4,200 feet), and its frequent occurrence at Xalapa (4,330 feet), as well as its prevalence on high points of the Andes (9,000 feet) (A. Smith), show that the effect of mere elevation has been overrated. Still, as a matter of precaution, stations in all yellow fever districts should be on elevations above 2,000, and if possible 3,000 feet. 4. If an outbreak of yellow fever occur in a barrack, it is impossible then to attempt any cleansing of sewers; the only plan is to evacuate the barracks. This has been done many times in the West Indies with the best effects. As a preventive measure, also, evacuation of the barracks, and encampment at some little distance, is a most useful plan. Before the barrack is reoccupied, every possible means should be taken to cleanse it; sewers should be thoroughly flushed; walls scraped, limewashed, and fumigated with nitrous acid. If a barrack cannot be altogether abandoned, the ground floors should be disused. There are several instances in which persons living in the lowest story have been attacked, while those above have escaped. See Aitken's Medicine, and Report on Hygiene in the Army Medical Report for 1862. Dr. Perry (op. cit.) considers quarantine useless, and advises a most rigorous system of disinfection. He cites eight instances of the introduction of yellow fever through a strict quarantine, seven to New Orleans, and one to Pensacola. 5. In all buildings where sick are, or where yellow fever prevails, there should be constant fumigation with nitrous acid, which seems to be, as far as we know, the best disinfectant for this disease. 6. If it appears on board ship, take the same precautions with regard to evacuations, bedding, etc. Treat all patients in the open air on deck, if the weather permit; run the ship for a colder latitude; land all the sick as soon as possible, and cleanse and fumigate the ship. Internal Cause.-Recent arrival in a hot country has been usually assigned as a cause, but the confusion between true yellow fever and severe febricula (ardent fever or causus) and malarious fevers, renders it uncertain how far this cause operates. Still, as a matter of precaution, the present plan of three or four years' Mediterranean service before passing to the West Indies seems desirable, although this has been questioned by some experienced officers. Different races possess the peculiar habit which allows the external cause to act in very different degrees; this is marked in the cases of negroes and mulattoes as compared with white men, but even in the European nations it has been supposed that the northern are more subject than the southern nations. Of the sexes, women are said to be less liable than men. 2 This predisposition is increased by fatigue, and it is said, especially when combined with exposure to the sun; by drinking, and by improper food of any kind which lowers the tone of the body. No prophylactic medicine is known; quinine is quite useless. Little, therefore, can be done to avert the internal causes, except care in not undergoing great fatigue, temperance, and proper food. The external conditions are the most important to attend to. 66 Dengue. This disease, which has attracted much attention of late years, appears to bear some relation to yellow fever, not in its pathological characters, but in the time of its appearance and geographical distribution. It has, however, prevailed in Asia, where yellow fever has hitherto been unknown. In Egypt (according to Vauvray) it is seen at the time of the date-harvest, and is known as date fever." In other parts of the world it has been attributed to vegetable emanations. Although its symptoms are those of bloodpoisoning, it may be doubted if this is due to vegetable emanations only. Dr. J. Christie thinks that the Dengue of the Eastern and the Dandy fever of the Western Hemisphere are varieties of the same disease, produced in the one case by the virus of yellow fever, and in the other by that of cholera, modified by local conditions of an insanitary kind, chiefly decomposition of bodies improperly interred. He suggests general hygienic measures, and especially improved methods of burial, as the best preventives. 3 In the old times in Jamaica it was, however, always noticed that the worst attacks occurred in regiments during the first twenty-four, and especially the first twelve months. In thirteen epidemics in different regiments, four occurred in less than six months after landing, seven in less than twelve months, and two in less than twentyfour months. But it has been stated that residence in one place, though it may secure against the yellow fever of that, does not protect against the disease in another locality. It is much to be wished that all these assertions which abound in books should be tested by figures. That is the only way of coming to a decision. Arnold, Bilious Remittent Fever, 1840, p. 32. Transactions of the International Medical Congress, 1882, vol. iv., p. 636. Cholera. External Cause.-As in the case of yellow fever, we have no certain clue to the origin of cholera,' and in some respects the propagation of the disease is very enigmatical. The way, for example, in which the disease has spread over vast regions, and has then entirely disappeared,' and the mode in which it seems to develop and decline in a locality, in a sort of regular order and at certain seasons, are facts which we can only imperfectly explain. But as far as preventive measures are concerned, the researches of late years seem to have given us indications on which we are bound to act, though they are based only on a partial knowledge of the laws of spread of this poison. These indications are 1. The portability of the disease, i.e., the carriage of cholera from one place to another by persons ill with the disease, both in the earliest stage (the so-called premonitory diarrhoea), and the latter period, and in conva lescence. The carriage by healthy persons coming from infected districts is not so certain; but there is some evidence. It is clear this last point is a most important one, in which it is desirable to have more complete evidence. The occasional carriage by soiled clothes, though not on the whole common, has also evidence in its favor. All these points were affirmed by the Vienna Conference of 1874. Even Pettenkofer admitted that man is the carrier of the disease germ, although the locality may be the means of rendering it potent. On the other hand, Dr. J. M. Cuningham' makes a tabula rasa of everything, denies the transportability of the disease either by persons or by water, and says there is a mysterious factor still to be sought for. His evidence, however, cannot be considered as conclusive. Whatever may be the final opinion on all these points, we are bound to act as if they were perfectly ascertained. It is usually impossible to have rigid quarantines; for nothing short of absolute non-communication would be useful, and this is impossible except in exceptional cases. For persons very slightly ill, or who have the disease in them but are not yet apparently ill, or possibly who are not and will not be ill at all, can give the disease, and therefore a selection of dangerous persons cannot be made. Then as the incubative stage can certainly last for ten or twelve days, and there are some good cases on record where it has lasted for more than twenty, it is clear that quarantine, unless enforced for at least the last period of time, The researches of Lewis and D. D. Cunningham in India, and of Eberth, of Zürich (Zur Kenntniss der Bacteritischen Mykosen, von J. C. Eberth, 1873), have shown that no specific germ has been yet discovered, and have disproved the fungoid and other origins proposed by Hallier, etc. 2 There is, of course, no doubt that the common autumnal cholera, however much it may resemble superficially the Indian cholera, is quite a separate disease. 3 With respect to convalescence, the only evidence is apparently that given by Volz, quoted by Hirsch, Jahresb. für ges. Med., 1868, Band ii., p. 221. Especially in the Mauritius outbreaks, where parties of coolies coming from places where cholera prevailed, but being themselves healthy, gave cholera to other parties of coolies who had arrived from India, and had no disease among them. Dr. Leith Adams (Army Medical Report, vol. vi., p. 348), in his excellent Report on Cholera in Malta, states: "There are many pointed facts to show that cholera may be introduced and communicated to susceptible persons by healthy individuals from infected districts." Ninth Annual Report of the Sanitary Commissioner with the Government of may be useless. The constant evasions also of the most strict cordon render such plans always useless. An island, or an inland village, far removed from commerce, and capable for a time of doing without it, may practise quarantine and preserve itself; but, in other circumstances, both theory and actual experience show that quarantine fails.' M. Fauvel believes that the quarantine measures adopted in the Red Sea have been instrumental in preventing the spread of cholera to Europe on three separate occasions, namely, 1872, 1877, and 1881. This difficulty, however, of carrying out efficient isolation is no argument against taking every precaution against communication, and keeping a strict watch and control over every possible channel of introduction. In this way, by isolation of the individual, or of bodies of men, as far as possible, and by looking out for and dealing with the earliest case, an outbreak may perhaps be checked, especially by discovering the diarrhoeal attacks, and by using disinfectants both to the discharges and to linen.' In the case of troops coming from infected districts they should be kept in separate buildings for twenty days, and ordered to use only the latrines attached to them, in which disinfectants should be freely used. 2. The introduction of the disease into any place by persons is considered by most observers to be connected with the choleraic discharges, either when newly passed, or, according to some, when decomposing. The reasons for this are briefly these: the portability being certain, the thing carried is more likely to be in the discharges from the stomach and bowels than from the skin or breath (the urine is out of the question), and for these reasons: Water can communicate the disease, and this could only be by contamination with the discharges; water contaminated by discharges. has actually given the disease, as in Dr. Macnamara's cases; in some cases a singularly local origin is proved, and this is nearly always a latrine, sewer, or receptacle of discharges, or a soil impregnated with choleraic evacuations; soiled linen has sometimes given it, and this is far more likely to be from discharges than from the perspiration; animals (white mice and rabbits) have had cholera produced in them from feeding on the dried discharges. Finally, in the history of the portability of cholera, there are many instances in which, while there has been decided introduction by a diseased person into a place, there has been no immediate relation between that person and the next case; in other words, the cause must be completely detachable from the first case, and must be able to act at a distance from his body; it is therefore far more probable that the discharges are this 1 When circumstances are favorable (as respects trade and intercourse), however, good quarantine may be successful even on the mainland. This was shown in Algeria in 1861. See Dr. Dukerley's Notice sur les Mesures de Préservation prises à Batna (Algérie) pendant le Choléra de 1867, Paris, 1868, for a very interesting account of those successful measures of which strict isolation and constant hygienic measures were the principal. So also in America, Dr. Woodward states (Circular on Cholera, No. 5, Surgeon-General's Office, Washington, 1867) that "the general tenor of army experience is strongly in favor of quarantine." Quarantine on land was condemned by the Vienna Conference, but recommended on the Red Sea and the Caspian. In Europe, however, only rigorous inspection was recommended, with various rules for preventing spread as much as possible. * Revue d'Hygiène, vol. iv., 1882, p. 754. * The Indian Government are now cautiously attempting to limit the spread of cholera by superintending and controlling the pilgrimages, which are so common a cause of the spread of cholera in India. The Report of the Cholera Committee (Inspector-General Mackenzie, Colonel Silva, and Dr. Ranking) to the Madras Government, published at Madras in 1868, gives a great deal of important evidence on this point, and in addition lays down excellent rules for the management of pilgrimages. |