A MANUAL

OF THE

PRACTICE OF MEDICINE.

I. THE INFECTIOUS DISEASES.

TYPHOID FEVER.

Definition and Synonyms.-Typhoid fever is an acute infectious disease caused by a specific bacillus, and is characterized anatomically by lesions of the intestinal and mesenteric glands and by enlargement of the spleen. The disease runs a febrile course of three or four weeks, with a characteristic eruption and systemic symptoms. Synonyms: Typhus fever (German); Abdominal typhus; Ileo-typhus ; Enteric fever; Autumnal fever.

Etiology.-Typhoid fever is one of the most widely spread of all the infectious fevers; it occurs in all countries and in all climates, though it is more frequent in the temperate zones. It may occur at any time of the year, but it is most commonly seen in late summer and in early fall, hence the name "autumnal fever" which has sometimes been applied to it. It seems to occur with especial frequency after hot, dry summers.

The disease affects the sexes equally, although in hospital practice more cases are met with in men, because they more readily apply for hospital treatment.

The disease may occur at any age, but young adults between the ages of fifteen and twenty-five are especially

susceptible. After the age of thirty-five the disease appears progressively infrequent.

There is in this disease, as in all infectious diseases, a great difference in personal susceptibility, some individuals. being more readily infected than others who have been subjected to the same degree of exposure. In cities strangers are more susceptible to this fever than old inhabitants. The development of the disease after exposure is favored by any inflammatory condition of the intestine, the entrance of the germ into the lymphatics being favored by the epithelial desquamation resulting from the catarrhal process. A low and sickly condition of the general health does not seem to increase the susceptibility to infection. The disease appears in both epidemic and endemic forms. The epidemics are usually local, affecting a group of houses, an institution, or a part of a town. The longer the epidemic, the more difficult it often is to trace the source of infection. It appears as an endemic disease where it had previously existed as an epidemic, and it is endemic in almost all large cities. The source of infection is with difficulty traced in endemic cases.

The actual exciting cause of typhoid fever is now proved to be the infection of the patient by a specific germ known as the bacillus typhosus, or Eberth's bacillus. This germ is a short, mobile bacillus whose length is equal to one-third the diameter of a red blood-cell, and having rounded bulbous ends which often present a shining appearance, due rather to alterations in its protoplasm than to spore-growth, as was at first supposed. In its appearance and growth this germ closely resembles the bacterium coli commune, or ordinary colon-bacillus, from which it is hard to differentiate it. The typhoid bacillus grows with ease in almost every kind of nutritive media, and it possesses extraordinary vitality. It may persist in drinking-water or in the soil for weeks or for months, and may even increase in number. It grows with

great rapidity in milk without altering its appearance or taste; and so great is its tenacity of life that it may remain imprisoned in ice for months without losing its virulent properties. In the accumulations of privy-vaults and sewers it finds conditions most favorable for its growth and activity. Cultures are killed by a temperature of 60° C., by carbolic acid (1:200), and by corrosive-sublimate solution (1:2500). Cultures resist drying for several days, but the growth of the bacilli is retarded by exposure to sunlight.

The bacillus obtains entrance to the body through the alimentary canal, and enters the intestinal lymphoid tissue probably through abrasions of the epithelial coat. It has been found in the lymphoid tissue of the intestines, in the mesenteric glands, the spleen, the liver, at times in the blood taken from the rose spots, and occasionally in the urine. It has been found also in some of the complicating lesions of the disease. The bacilli are found in clusters in the intestinal contents and the stools of patients, and are thrown out from the body in this way. They are not eliminated from the lungs or the skin.

Methods of Infection.-The disease is in no sense personally contagious, cases of typhoid being received into the general wards of hospitals without risk. The bacilli being cast off only in the dejecta of the patient, it is from the stools that danger of infection arises. If the stools are thoroughly disinfected and the bacilli are killed, there is no further risk of a spread of the infection. If the stools are not disinfected, however, the bacilli will live and thrive in them, and this infected sewage, draining into water-supplies, will spread the disease among those who drink of such

water.

There are three ways by which the infection of typhoid may occur:

The first method is by direct infection from stools. While

not common, infection has occurred among attendants on the sick and among those who have washed the soiled linen of typhoid patients, the germs being transferred from infected hands to the food, and thus obtaining entrance to the body.

The second method of infection is by contamination of the water-supply. This is the usual source of infection, and it explains the origin of epidemics of the disease that occur from time to time in towns, in institutions, and in villages. Contamination of drinking-water with filth and sewage will not produce the disease unless to such sewage is added the specific germ. Interesting investigations of epidemics frequently show their origin in the contamination of the water-supply by the dejecta of a single typhoid patient, even though months may have elapsed between the infection of the sewage and the consequent contamination of the water-supply. The source of contamination is most easily traced in small epidemics, and examples of epidemics in hotels, villages, and towns so traced are to be found reported in full in medical literature. In the same way the infection may be conveyed by impure ice, after the thawing of which the germs regain their vitality.

The third method of infection is by means of milk, in which the bacilli readily thrive, and to which they are added by impure water used either to wash the cans or to dilute the milk.

There are reports of epidemics apparently caused by eating meat of diseased cattle, but this mode of infection is not yet definitely determined. Poor drainage, sewer-gas, and imperfect hygiene will not of themselves cause the disease: they only offer favorable conditions for the growth and development of the bacillus.

Pathology. The lesions are divided into those essential to, and those complicating, the disease.