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ON THE DURATION OF CONTAGIOUSNESS AFTER

ACUTE INFECTIOUS DISEASES.

By ALFRED LUDLOW CARROLL, M. D., of Richmond County.

Read November 18, 1884.

UNDER most sanitary authorities, a salutary regulation exists forbidding the return to school of any pupil convalescent from a contagious disease, except upon a medical certificate that the danger of infection is past; and, aside from this very necessary precaution against the perpetuation and dissemination of infection in schools or through other public intercourse, our more private duties to our clients almost daily call on us to decide when it may be safe to permit the restoration to the family circle of some patient whom we have been carefully isolating in a separate chamber during the course of an acute infectious disorder. From many points of view, therefore, this inquiry is one of great practical importance to the public and to our profession; and yet, in the present state of our knowledge, it is one of the most difficult to answer. We know the limits of incubation of most of the infectious zymoses; we know something of the ætiology of many of them ; we know much of their natural history; and we are unlearning much as regards their treatment. But, in our narrow field of observation, we know nothing of the wider and more momentous question: When do they cease to threaten others than the individual under our care? In our preventive efforts, we have for years gone on in blind empiricism, erring, perhaps—as it is the proper part of ignorance to do on the side of overcautiousness, but without any definite facts to guide us. Much

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time must elapse, and many accurate observations be made, before such facts can be established and fixed rules of conduct deduced from them; and my intention is, not to advance any new theories, but simply to present for consideration a subject which, in an assemblage such as this, may profitably serve as material for “collective investigation."

In the consideration of this question, we must theoretically exclude the retention of the several contagia by fomites. Without doubt, much perplexity has hitherto arisen from the undetermined part played by infected clothing resumed by the convalescent patient, or by other inanimate articles. For our present purpose, we must assume that proper measures of disinfection have been pursued with regard to these, and that we have to deal solely with the body or the excreta of the individual.

Another element of uncertainty lies in the “personal factor”; the varying susceptibility to infection of different persons, or of the same person at different times. Of a hundred unprotected persons exposed to the contagium of small-pox, measles, or any other infectious zymosis, a considerable percentage will escape infection; but their immunity is, of course, no evidence that the transmissibility of the virus has ceased.

At the present day most of us, probably, are convinced that, in the majority, if not in all of the communicable zy moses, certain forms of microphytes act, if not as the specific causes, at all events as the carriers of disease; and, from this point of view, our ultimate certitude as to the question at issue must come from further biological research into the life-history of the various pathogenic or pathophorous schizophytes and the latent vitality of their resting spores. But, in the mean time, our course must be shaped according to the best conducted observations at our command.

The only attempt within my knowledge to formulate experience in respect of the duration of infectiousness is that of Dr. Miller, of Dundee,' whose tabulation is as follows:

Small-pox....... 14 days after termination of scabbing.
Typhus......... 28 days from inception.

“British Medical Journal,” July 30, 1881, No. 1074, p. 173.

Scarlet fever..... 7 weeks from inception.
Diphtheria..... 6 weeks from inception.
Whooping-cough. 8 weeks from inception.
Measles.... 6 weeks from inception.

The first thing that strikes one about this table is the omission of any estimate of the duration of infectiousness in the discharges from such diseases as enteric fever or cholera ; the second, the rather arbitrary assumption of intervals which, in some instances, may seem unnecessarily long.

In order to ascertain if there were any consensus of professional opinion regarding the points so often brought before me in my official position, I addressed, some months ago, a note of inquiry to several of the leading medical teachers and hospital physicians of this and other cities, whose names, for the present, I shall leave unmentioned, as their kind replies were intended to form the basis of a report to the State Board of Health. I may, however, briefly recapitulate the views presented in their valued communications.

SMALL-POX.--As to small-pox, there is practically unanimity in regarding the danger as existing until all crusts are removed ; but a few incline to prolong even further the period of isolation. One of our most eminent teachers writes that at least eight weeks should elapse ... before a child that has been affected with it should be allowed to return to school." On the other hand, a gentleman of wide sanitary experience apprehends but little danger from the crusts which sometimes linger under the thick skin of the soles and palms, provided that every scab be removed from the body and hair, and that thorough cleansing of the surface be effected. Other correspondents fix the duration of quarantine “during the whole of desquamation"; "until the cicatrices are fully healed"; "until all traces of the cutaneous affection have disappeared and everything is removed from the surface of the body by repeated ablutions”; and other replies are to the same effect; while one writer approves, in general terms, the rule of the Boston Board of Health, as regards all infectious disorders, that four weeks should elapse from the beginning of the last case of disease in the family, before a patient should be allowed to attend school.

TYPHUS FEVER.-In relation to typhus, the responses are fewer and less in accord. One deems fomites the most important factor in the dissemination of the malady, while the rest lay stress on personal contagion. One regards it as “not contagious after a short interval”; a second advises segregation until repeated baths have followed the complete disappearance of the cutaneous exanthem; a third, somewhat indefinitely, would permit return to school “after complete recovery and disinfection.”

TYPHOID FEVER.—Those who believe in the direct personal contagiousness of enteric fever are few in number; and I fancy that nearly all of us will agree that the intestinal discharges are all with which preventive medicine has concern. Whether these retain their infectious properties during the whole process of the malady, is a question still in uncertainty, and rendered more obscure by the apparent demonstration that the disorder may, under certain undetermined circumstances, be generated de novo from ordinary sources of filth-poisoning. At all events, isolation of the person seems unnecessary as soon as convalescence is complete.

The same considerations will apply, I believe, to cholera, with the further remark that, if Koch's recent observations be correct, the germs of this disease appear to be shorter-lived than any other known species, being destroyed, not only by desiccation, but by the “scavenger bacteria," which conquer them in the struggle for existence in the products of common decomposition.

DIPHTHERIA.—Diphtheria affords a wider debatable ground. To begin with, there are many (among whom my own experience forces me to class myself) who assign the first place in the pathogeny of diphtheria to filth-poisoning and doubt its exceeding contagiousness. Of a number of persons exposed to the same pathogenic conditions, it is not surprising that several should succumb; but this is not convincing evidence of transmission from one to the other, and I have seen repeated instances where, despite intimate contact, the disease failed to

extend after its introduction into places in proper sanitary condition. Moreover, the experiments of Péter and Trousseau serve to show, at least, that diphtheria is not contagious under all circumstances. One of my correspondents, who has long had charge of a large hospital for children, believes this malady to be “feebly, if at all, contagious,” and finds it quite safe to remit quarantine “after the disappearance of membranes”; a practical sanitarian, of national reputation, excluding fomites and filth in air and water, does not believe in personal contagion; a distinguished teacher in one of our metropolitan colleges doubts “its communicability, except by contact ”; another, equally eminent, declares that contagiousness endures until the last trace of inflammation or infiltration secondary to the diphtheritic process has disappeared; a fourth would protract the duration of quarantine for a month, or, at least, three weeks, after all symptoms have abated, and would forbid return to school while any redness of the fauces or any coryza lingers. The discrepancy of opinions in this respect among the leaders of professional thought suffices to show the need of more definite data to guide our deliberations.

WHOOPING-Cough.—In pertussis, all opinions agree, save one, that contagiousness ends when the cough loses its spasmodic character; the single doubtful view being that, as the danger is wholly from the breath of the patient, it cannot be determined how long the cough may convey infection. It should be remembered, however, that a few writers have expressed doubts of the contagiousness of pertussis in any stage.

MEASLES.—With regard to measles, I find equal diversity of views. One regards its contagium as very volatile, not long adhering to person or clothing, and permits the return of the patient to school in two weeks after convalescence; a second would defer liberation from quarantine until a week, at least, after desquamation; a third releases the patient when desquamation has ceased, or, in cases where no desquamation occurs, after twenty-one days; a fourth fixes eighteen days; a fifth be

1 Vide a paper by Dr. M. A. Avery, Assistant Physician to the Nursery and Child's Hospital, in the “N, Y. Medical Journal,” February, 1882,

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