OTHER ASPECTS OF INFECTIOUS DISEASE I. In the foregoing chapters we have considered a number of the infectious diseases of public health importance in the United States. These for the most part are diseases which are systemic in character and the losses we have considered have been direct losses either from sickness or death. There is another type of damage which these diseases may produce that is fully as important as the losses we have heretofore con sidered, namely the sequel2e. These consist of a permanent injury or impairment of function arising from the illness, as a consequence of which the individual may never be restored to the degree of physical efficiency existing before the illness, and while he may recover from the infection, the permanent damage may either assist in the development of other patho logical processes which shorten life or reduce the economic efficiency of the individual. We will briefly consider the injuries of this character. But little quantitative data on this point are available, so the presentation will deal necessarily with generalities.
In a study of nearly two thousand cases of typhoid fever, Dublin finds that cardiac disease and a lowered resistance to tuberculosis are the most important sequel manifesting their effect within three years following recovery. He concludes that during this period the mortality is twice that among in dividuals who have not had typhoid fever. It is usually con sidered that with typhoid, ten per cent. of the cases have a fatal outcome. He points out that in addition, the which produce a fatal outcome increase this mortality very nearly by five per cent. The fact that an increased mortality from tuberculosis is observed is very important. Many of the acute infections so undermine the individual's resistance to a more chronic infection such as tuberculosis, to an extent that a heretofore latent infection becomes active or the nephritis appearing as a complication of scarlet fever may fail to clear up with convalescence, and remain as a permanent injury to the individual. Diphtheria toxin may permanently impair the nervous system, so that the post-diphtheritic paralyses are one of the most dreaded sequelx of any disease. Likewise the great popular horror of poliomyelitis arises from the disabling paral ysis so common in those who recover. The greatest progress we have made with poliomyelitis in recent years has been in the intelligent orthopedic handling of these cases. The results are
so striking and so beneficial that many progressive state health authorities are now following up all poliomyelitis cases and making provision for orthopedic relief. Similar disablement may follow cerebrospinal meningitis, together with deafness. Noticeable mental or nervous impairment may follow typhus fever or whooping cough. Gonorrheal infection of the geni talia in either male or female is frequently responsible for sub sequent sterility of the individuals, and where infection is transferred to the eye, permanent blindness may result. After the active infective stages of syphilis are past the individual may suffer great physical disability from the lesions the tertiary and quaternary stages. It is therefore apparent that the ravages of those diseases are not sufficiently brought out by a study of the mortality or morbidity records alone.
Another aspect of this subject is that of the so-called "focal infections" whose importance was first emphasized by Billings and his associates. Chronic infection localized in some ob scure area of the body may be responsible for the production of acute rheumatism, chronic deforming arthritis, gonorrheal arthritis, malignant endocarditis, myositis, myocarditis, sep ticemias of several types, certain infectious types of thyroiditis with or without hyperthyroidism, acute and chronic pancreatitis with or without glycosuria, gastric ulcer and cholecystitis. The situations in which the chronic infection is localized are most commonly the dental alveoli, the tonsils, the gall bladder, the appendix or a nasal sinus. From these locations bacterial emboli are thrown off into the circulation, and if the defenses of the body are diminished by overwork, exposure to cold, dissipa tion, insufficient or improper food, unhygienic surroundings, injuries from former diseases (valvular scars) or trauma, some of the conditions mentioned may develop. The responsible micro-organisms are most commonly those of the pneumococcus streptococcus group. From a public health standpoint these conditions do not come to the attention of the health authorities except in so far as they participate in mortality production. But from the standpoint of the practising physician they are a field of preventive medicine in which brilliant results may be secured by searching for the chronic focus of infection and effecting its removal.