Sessional_Paper_1906 — Page 219

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Probable Causation.

We do not here intend to discuss any of the theories regarding the causation of Beri-beri in general, but merely wish to call attention to a few points in con- nection with this particular outbreak. The predisposing causes we can point to fairly clearly. The disease broke out among an overcrowded, stagnant population resident in a building which we consider is ill-ventilated, and in addition is damp and ineffectually sunned. This much is easy of assertion and of proof. When however we come to consider what may be the exciting cause or causes we under- take a more difficult task. For we are unable to assign a cause to the outbreak. We can only point to the fact that when the conditions of residence were amelior- ated the disease ceased spreading. As soon as the inmates were removed to the large, airy wards of the Tung Wah Hospital the incidence of the disease was arrest- ed. Only two wards were occupied and the inmates crowded into them—but these were large, airy wards with wide doors on every side and the sun's rays pe- netrated into them all day. The food remaining the same in both establishments; it is perhaps a question whether it acts as a factor in causation, and if it does whether it requires certain conditions of crowding and surrounding to bring it into play. With this particular outbreak it was noticed that the patients improved on transfer, and that only one or two fresh cases occurred after transfer these pro- bably incubating at that particular period.

Prognosis.

With such mild, and mildly severe cases, the prognosis is invariably favour- able. Of the 32 patients attacked all recovered except one. This patient had a rather more severe attack than the others. She quickly lost the power of move- ment and became confiued to bed. The dema of the legs became more pro- nounced and after a time the heart began to act badly-dilatation shewed itself, and after a time she contracted subacute pneumonia to which she sucumbed. Favourable points in prognosis are mildness of attack, as evidenced by power of locomotion if even slight, non involvement of the heart, and a moderate degree of anæmia. Then also the prognosis is most favourably influenced by prompt re- moval from the premises in which the disease developed or manifested itself—and removal if possible to well ventilated, sunny, airy premises.

Period of Incubation.

There is a diversity of opinion regarding the duration of the period of incu- bation of the disease, and in this series of cases also we meet with extremes. Assuming that the disease was contracted within the building, and that the infect- ion was present or developed therein, we can calculate the length of time the pa- tient was subjected to its influence before manifesting the earliest symptoms. And this period we night assume to be the period of incubation. From such an estimation we set a variation between a maximum period of 200 days in one case, and a minimum of 23 days in another. Between these periods we have varying periods--lengthy in some cases, such as 184, 147, 119, 117 and 131 days and com- paratively short in others, such as 31, 53, 63 and 68 days. Calculating an average from these periods we set a period of 84 days, which we might call the period of incubation. [This of course only applies to this particular series of very inild cases in very acute cases the incubation period has been known to be not much more than 40-50 hours].

During this period the symptoms are apparently very trifling and not such as to lead the patient to make any complaint nor such as to cause any inconvenience. Perhaps slight digestive disturbances or slight palpitation may be forerunners : certainly a condition of anæmia supervenes. Sometimes amenorrhoea may occur which in young females should lead to a suspicion of the cause, especially in a loca- lity where the disease is endemic. So that it may be said that the incubation period is prolonged, the symptoms vague and indefinite, leading to the conclusion that the poison is slow working, and its result cumulative.