All infectious diseases may spread in consequence of war and develop into epidemics of varying extent. In the next chapter we shall see how the wars at the end of the fifteenth century favoured the spread of an epidemic of syphilis. In the Union Army, during the American Civil War of 1861–5, both measles and typhoid fever were very widespread, and together they were the cause of 4,246 deaths, or about 1·75 per cent of the total enlistment. Scarlet fever, influenza, yellow fever, relapsing fever, and malaria (if the war is waged in countries where this disease is endemic—especially in the Lower Danube region, in the Netherlands, Spain, and Italy) have also played an important rÔle in many wars. But we give the name ‘war pestilences’ only to those infectious diseases which in the course of centuries have usually followed at the heels of belligerent armies, such as typhus fever, bubonic plague, cholera, typhoid fever, dysentery, and small-pox; we may also include here scurvy, the etiology of which has not yet been definitely determined.

1. Typhus fever (spotted fever, exanthematic typhus—called in France and England simply typhus, in Spain tabardillo^[2]—formerly called contagious typhus, hunger typhus, camp fever, and Hungarian fever) is an acute infectious disease of cyclic recurrence, which resembles typhoid fever only in name. From the eighth to the tenth day after infection, often somewhat sooner or later, it begins with a chill, accompanied by nausea, vomiting, violent headache, and psychic depression. In the first few days the patient’s temperature rises rapidly, and on the fourth or fifth day a rash in the form of dull-red spots, as large as a pea, breaks out over the entire body. These spots gradually grow larger, and after two or three days, through the appearance of very small haemorrhages, change into petechiae. The apathy of which the patient first gave evidence now gives way to wild delirium. At the end of the second week the temperature falls rapidly, and in one or two days becomes normal; often, however, the fall of temperature takes from six to eight days. The duration of the entire disease, accordingly, is from two to two and a half weeks. Death usually occurs at the crisis of the disease—from the tenth to the twelfth day—rarely between the sixth and ninth days or after the twelfth.

The danger of the disease varies greatly in different epidemics; statements regarding this point diverge according as we refer to the statistical records of hospitals or to the private practice of physicians. With the latter the number of deaths is smaller, since persons suffering from the disease in mild form less often go to the hospitals. Epidemics in which a quarter of the patients, and even more, have succumbed have frequently occurred, especially in war times, during famines, &c. The cause (infective agent) of typhus fever is not known; according to recent investigations it is spread by vermin; Ricketts and others have fixed responsibility for it upon the body louse. The infection is communicated from man to man, and very often it is contracted from the clothes, linen, and other effects of typhus patients. Recovery from the disease usually renders a person immune against a second attack. Typhus fever frequently appears nowadays in the eastern and south-eastern parts of Europe, in Hungary and Galicia, and also in Spain, Italy, and Ireland.

2. Plague appears in two forms, depending upon the place where the infective agent enters the body: the bubonic plague and the pneumonic plague. In the case of the former the painful plague-sores (buboes) develop, usually two or three days after infection, from the lymphatic glands; these sores,—which appear most often in the region of the groin, less often in the axilla, on the neck, lower jaw, and in other places,—soon suppurate. There is either a development of toxins, which are the cause of the severe general symptoms, or else the bacilli pestis go from the glands into the circulatory system and cause septicaemia, which is quickly fatal. Pneumonic plague takes the form of a catarrhal inflammation of the lungs, causing a profuse and bloody expectoration, which contains large quantities of bacilli. This form of the disease almost always ends fatally in a few days. The mortality of bubonic plague is somewhat lower; the disease has an average duration of eight days, and carries away from fifty to seventy per cent of its victims.

In the Middle Ages an epidemic of plague (black death) ravaged all Europe. At the present time it is still endemic in India, in southern China, in Egypt, in Uganda, and perhaps in other countries, whence it frequently develops into general epidemics.

The infective agent in the case of plague is the bacillus pestis, identified in 1894 by Kitasato, and subsequently, but independently, by Yersin. Rats, which are very susceptible to the disease, play an important rÔle in spreading it; in India the outbreak of a plague epidemic is always preceded by the dying of large numbers of rats. Their excrement contains large quantities of bacilli, which may be destructive to human beings. The rat-flea is also known to carry the infection. The infection may be conveyed directly by plague patients, when the buboes suppurate, or when the blood becomes generally infected with the bacilli pestis, which are contained in abundance in the sputum, urine, and excrement, or when the lungs are affected and the patient charges the atmosphere by coughing. One who has recovered from the disease is usually immune for life.

3. Cholera, after an incubation period of two to eight days, begins with frequent (ten to twenty times a day) vomitings of a fluid like rice-water, and incessant retching. The patient, owing to the great loss of water, sinks rapidly; he acquires a corpse-like appearance, loses consciousness, and death may result on the first or second day. If the attack is survived, the patient frequently dies from sheer exhaustion afterwards. The mortality of cholera is great—from forty to fifty per cent of its victims die. In this calculation the numerous cases of cholerine, that are always prevalent during cholera times, are excluded. Recovery from the disease does not protect a person against contracting it again. The infective germ in the case of cholera is the ‘comma bacillus’, discovered by Robert Koch in 1883. The spread of cholera is caused by the penetration of the comma bacillus into the alimentary canal, resulting from contact with objects which have been contaminated by the evacuations of cholera patients; less frequently it is indirectly caused by the pollution, from evacuations, of water used for drinking or washing purposes.

4. Dysentery has always played an important rÔle in military campaigns. To be sure, it is not very dangerous, so far as the patient’s life is concerned, but in war times, owing to irregular nursing and scanty nourishment, and the consequent use of unsuitable food, it may spread over a large territory and be very destructive to large numbers of soldiers and other people.

There are two distinct forms of the disease—amoebic dysentery and bacillary dysentery. The latter is caused by the bacillus pyocyaneus, discovered independently by Stiga, Kruse, and Flexner. The disease used to be common throughout Europe; at the present time it appears in Central and Western Europe only in small epidemics, whereas in Eastern Europe it spreads over large territories. It causes frequent, often blood-coloured, defecations, accompanied by griping pains in the abdomen and a distressing pressure (tenesmus). The disease lasts from one to one and a half weeks, but for a long time after recovery the patient’s alimentary canal is very sensitive to improper nourishment. The disease is transmitted either by direct contact, since the evacuations of the bowels contain large quantities of bacilli, or by infected water. Amoebic dysentery, occurring in tropical countries (Southern Europe, Egypt, Southern Asia, Central America, &c.), is much more dangerous; it is caused by an amoeba, carefully studied by Kartulis, and very often acquires a chronic character, sometimes causing abscess of the liver.

5. Typhoid fever (called in England ‘enteric fever’, in France ‘fiÈvre typhoÏde’, in Italy ‘febbre tifoidea’) in many wars has been very widespread among the armies; for example, in the American Civil War, in the Franco-German War (Metz), and in the Russo-Turkish War of 1877–8. The progress of the disease is well known; between the time of infection and the outbreak of the sickness nine to eleven days usually intervene, sometimes even as much as three weeks. In the first week the temperature of the patient rises slowly, during the second week it remains at about the same height, while in the third week it abates considerably, becoming normal in the course of the fourth week. The spleen enlarges a great deal, and in the second week small pale-red spots (roseola), scarcely as large as a pea, appear on the buttocks and especially on the belly. The patient’s bowel-movements, at first normal, now becomes diarrhoeal, while certain psychic disorders also manifest themselves, usually in the form of a heavy somnolence. In the third week the patient’s life is threatened by complications in the intestines—haemorrhage or perforation. Characteristic of the disease are the anatomical changes of the small intestine—at first enlargement, and later ulceration of Peyer’s patches. The infective agent in the case of typhoid fever is a bacillus, identified by Gaffky in 1882. It lodges in the alimentary canal, and is conveyed by food that has been touched with hands to which matter containing the bacillus has adhered, or else in contaminated water used for drinking or other purposes. From eight to ten per cent of the patients die, while a single recovery usually insures immunity against a second attack.

6. Small-pox has an incubation period of ten to fourteen days. The disease begins with a chill, accompanied by violent headache. On the third day the eruption appears; little papules develop and quickly change into pustules, showing themselves first on the face, then on the back, arms, and hands, and finally on the legs and feet. On the ninth day the pustules suppurate, and after that gradually dry up; if it progresses favourably, the disease is over in two or two and a half weeks.

In the case of small-pox the infective agent is not yet known; infection is caused by contact with a patient, or with objects which he is using or has used. It is particularly dangerous to touch things on which the contents of the pustules have dried, for such articles remain infectious for a long time. Recovery from the disease usually renders a person immune for life. The mortality in different epidemics varies greatly; most dangerous of all is the so-called ‘black small-pox’ (haemorrhagic small-pox, with bleeding in the pustules and under the skin). The total number of deaths in an epidemic of small-pox is dependent upon whether the disease appears in a vaccinated or an unvaccinated community; in the latter case the mortality may reach thirty per cent, whereas in the former case only three or four per cent of the patients die. Vaccination renders a person immune for eight to twelve years, while, if the disease breaks out anywhere in spite of vaccination, the number of fatal cases is very few. It should be noted that small-pox was formerly dreaded, not only because of its danger to life, but also because it frequently leaves a person disfigured for life, and in rare instances causes total blindness.

7. Scorbutus (scurvy) used to be a common disease on ships, in prisons, and in times of famine; it appeared with the greatest malignancy in besieged cities—Thorn, Nuremberg, Alexandria, Port Arthur, &c. The real cause of the disease is unknown, although too much food of one kind, particularly lack of fresh vegetables, together with long confinement in poorly ventilated and dark rooms, are important causative factors. Inasmuch as the disease almost always appears in the form of an epidemic, it is probable that there is a specific infective agent. It begins with a general feeling of weakness; the skin and mucous membranes become pale and sallow, the gums become inflamed and ulcerated, and small and large extravasations of blood take place in the skin and muscles, and at the joints and knuckles. In serious cases haemorrhages occur in the intestines, kidneys, bladder, and uterus. A change of diet and surroundings will quickly cure scurvy; otherwise progressive anaemia will result in death.