ENTERIC OR TYPHOID FEVER.
Enteric fever causes its highest death-rate in early adult life, though it is not peculiar to any age. Eberth in 1880 discovered the Bacillus typhosus in the spleen and other organs of enteric fever patients. This is commonly known as Eberth’s bacillus, and is the cause of enteric fever. A few years later it was isolated and can now be grown on agar or gelatine in laboratories. It closely resembles other bacilli which are normal inhabitants of the human intestine; but can be distinguished by certain tests. It is a small rod, rounded at its ends, and from 2 to 4 µ long and three times as long as broad. In the living state it is freely motile, and possesses a number of minute cilia or flagella. Apart from other means of distinction between it and other bacilli, Grüber’s serum reaction enables its identity to be ascertained. The bacillus suspected to be the Bac.-typhosus is cultivated in broth in the bacteriological laboratory. A small quantity of blood is taken from the finger of a patient known to be suffering from enteric fever. The serum is separated from the blood corpuscles of this blood by a centrifugalising machine. A drop of the blood serum is diluted with 100 drops of broth culture of the suspected bacillus. If the latter is not the Bac.-typhosus, the individual bacilli when a drop of the mixture is examined under the microscope, will continue to move about freely; if it is the Bac.-typhosus, the bacilli will adhere together in “clumps” and become immobile. Conversely a valuable means of ascertaining whether a suspected case is really suffering from enteric fever is secured, as this blood added to 30 times the amount of a pure culture of the Bac.-typhosus in broth will cause the latter to “clump” within half-an-hour (Widal reaction). Higher dilutions are usually unnecessary.
The chief means of spread of enteric fever is by the urine and fæces; and nurses who have to empty bed-pans unless very careful to wash their hands afterwards, using the nail-brush, are very liable to become infected, probably when eating food afterwards. The urine in a considerable proportion of cases, contains the typhoid bacilli, and it is therefore most important that care should be exercised in the cleansing of all chamber utensils, and that the urine as well as the fæces should be rigidly disinfected (see page [331]). The infectivity of enteric fever has been underrated in the past. When patients with this disease are nursed at home by relatives who do not appreciate the full importance of the necessary precautions, it is rather the rule than the exception for them to fall victims to its infection. Probably, sometimes the infection has been scattered as dust, owing to small particles of fæces or of urine having become dried on bed linen. The most absolute cleanliness is essential in nursing this disease. In hot climates there is reason to believe that infective dust may be blown about from privies.
Insanitary local circumstances are an important means of spreading enteric fever. It is more prevalent where there are privies than where there are pail-closets; and more prevalent where there are pail-closets, than where water-closets are the rule. Defective drains or soil-pipes are frequently found in houses in which enteric fever originates, and there can be little doubt that the former are at least partially responsible for the latter. The exact link is doubtful. Probably infective dust is blown or aspirated into the room and is inhaled.
The most common cause of enteric fever is infected food or water. Of foods milk not infrequently has been the means of spread of enteric fever. Large epidemics have been traced to this source. Usually this has arisen by washing the milk cans with or wilfully adding contaminated water to the milk. Water, whether added to milk or taken independently, must have contained the specific contagium (the Bac.-typhosus) of enteric fever, to enable it to cause enteric fever. Hence water from a contaminated stream is more likely to have produced this effect than well-water, unless a patient has had enteric fever in the house to which the well is attached, and his dejecta have contaminated the water. Surface waters or spring waters may be contaminated with sewage (as at Maidstone) or deep well waters through fissures (as at Worthing) and thus widespread epidemics be produced. After floods, rivers and wells are most likely to contain the specific contagium of enteric fever, as at such times surface impurities from middens, etc., are apt to be washed into the water. (See also pages 91 and 224).
The means of prevention of enteric fever are the discovery and removal of the cause of an outbreak, and the isolation of each patient and disinfection of all discharges. An early means of diagnosis is secured by Widal’s reaction. This is especially useful in cases not presenting characteristic clinical symptoms. The recognition of a disease or at least the suspicion of its presence is an indispensable first step for the taking of precautionary measures.