Studies of influenza in hospitals of the British armies in France, 1918.

Date:
1919
Catalogue details

Licence: Public Domain Mark

Credit: Studies of influenza in hospitals of the British armies in France, 1918. Source: Wellcome Collection.

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    centration around the maximum. Further, a secondary epidemic is characterized by a vastly higher fatality than a primary epidemic. Through the kindness of the D.G.M.S., British Armies in France, and of Captain A. H. Greg, O.B.H., R.A.M.C., statisticai officer at the head-quarters of the D.M.S., L. of C., B.H.F., J have been enabled to prepare charts of incidence of the summer and autumn epidemics as they affected the British Expeditionary Force. As in Captain M. Greenwood’s curves, the abscissae are weeks, the ordinates, expressed in terms of the number of cases recorded in the worst week, show the incidence on the British armies in France. In the absence of accurate figures as to the case mortality in the summer epidemic, I have charted the total mortality per month, from all diseases, throughout the year. This brings out clearly the very slight effect of the summer epidemic upon the mortality from disease, while the marked and terrible influence of the autumn epidemic is well seen. The actual number of cases and, in the autumn epidemic, the case mortality, are shown in Tables I and II. It should be noted that, on the first appearance of the disease in May and June, many physicians preferred to use the non-committal description ‘ Pyrexia of Uncertain Origin ’ (P.U.O.) rather than the diagnosis * Influenza ’. Table I therefore includes the cases admitted to hospital under both headings. In the autumn epidemic many cases were diagnosed ‘ Broncho- pneumonia’ owing to the onset of this complication during the attack. The incidence under both headings is seen in Table II, but the totals have been used in compiling Chart I. From these tables and charts it will be at once apparent that the summer and autumn epidemics exhibited, in every particular, the characters cited by Captain M. Greenwood as typical of a primary and a secondary epidemic of influenza respectively. There can be no doubt that the two epidemics were identical in nature. The difference observed between the cases admitted in the summer and those seen in the autumn were differences in degree and depended on the enormously increased virulence of the infective agent in the secondary wave. Il. IMMUNITY FROM PREVIOUS ATTACKS. A question of great interest 1s whether those attacked during the summer outbreak retained any appreciable immunity in the autumn. No conclusive figures could be collected on this point owing to the errors necessarily introduced by the unequal proportion of replace- ments of personnel in units and formations during the intervening months. Some units, engaged in the severe fighting of the late summer and autumn, must have changed their whole personnel during the period under review, while others, such as L. of C. units, probably underwent but little change. The question of diagnosis also introduces difficulty, as common colds and slight attacks of simple pyrexia tend to be called influenza during epidemics of this disease, and it is by no means certain that a patient stating that he had had a previous attack had really suffered from the disease.