NA TURE 



145 



THURSDAY, DECEMBER 19, i{ 



THE EPIDEMIC OF INFLUENZA. 



FOR the first time after an immunity of nearly half 

 a century, our country is again threatened with 

 an epidemic of influenza. The accounts we receive of 

 epidemic illness in Russia, in Germany, and last of all 

 in Paris, seem to make its irruption here every week more 

 imminent. The question will,, however, naturally be asked 

 by the public, whether there is any real ground, in the 

 history and in what is known of the nature of the disease, 

 for such an apprehension.'' Is it a disease really brought 

 from a distance ? Is it anything more than the general 

 prevalence of catarrhal affections, of colds and coughs, 

 which the time of year, and the remarkably unsettled 

 weather we have lately experienced, make readily ex- 

 plicable without any foreign importation? Indeed, is 

 influenza, after all, anything more than a severe form of 

 the fashionable complaint of the season ? 



To answer the last question first, and so to put it by, 

 there can be little doubt that influenza is a distinct, 

 specific affection, and not a mere modification of the 

 common cold. The grounds for this belief cannot be 

 fully stated here, but may be gathered by reference to 

 the descriptions of the disease as seen in former out- 

 breaks by physicians of the older generation ; for instance, 

 by Sir Thomas Watson in his classical "Principles of 

 Physic," or the late Dr. Peacock in his article in Quain's 

 " Dictionary of Medicine." 



These symptoms, the history of the disease, and its 

 distribution, all justify us in treating it as a distinct and 

 specific disease, which when it is prevalent will rarely be 

 mistaken, though, with regard to isolated and sporadic 

 cases, difficulties of diagnosis may arise. About its 

 •nature, or its affinities with other diseases, it is unne- 

 cessary to speculate. It will be sufficient to inquire what 

 its recorded history in the past justifies us in expecting as 

 to its behaviour in the future. There are few cases in 

 which history proves so important an element in the 

 scientific conception of a disease as it does in that of 

 influenza. For hardly any disease shows a more marked 

 tendency to occur in epidemics — that is, in outbreaks 

 strictly limited in point of time. After long intervals of 

 inaction or apparent death, it springs up again. Its 

 chronology is very remarkable. Though probably occur- 

 ring in Europe from very early times, it first emerged as 

 a definitely known historical epidemic in the year 15 10. 

 Since then, more than 100 general European epidemics 

 have been recorded, besides nearly as many more limited 

 to certain localities. Many of them have in their origin 

 and progress exhibited the type to which that of the pre- 

 sent year seems to conform. We need not go further 

 back than the great epidemic of 1782, first traceable in 

 Russia, though there believed to have been derived from 

 Asia. In St. Petersburg, on January 2, coincidently 

 with a remarkable rise of temperature from 35" F. below 

 freezing to 5° above, 40,000 persons are said to have 

 been simultaneously taken ill. Thence the disease spread 

 over the Continent, where one-half of the inhabitants were 

 supposed to have been affected, and reached England in 

 Vol. xli. — No. 1051. 



May. It was a remarkable feature in this epidemic that 

 two fleets which left Portsmouth about the same time were 

 attacked by influenza at sea about the same day, though 

 they had no communication with each other or with the 

 shore. 



There were many epidemics in the first half of this 

 century ; and the most important of them showed a simi- 

 lar course and geographical distribution. In 1830 started 

 a formidable epidemic, the origin of which is referred to 

 China, but which at all events by the end of the year had 

 invaded Russia, and broke out in Petersburg in January 

 1 83 1. Germany and France were overrun in the spring, 

 and by June it had reached England. Again, two years 

 later, in January 1833, there was an outbreak in Russia, 

 which spread to Germany and France successively, and 

 on April 3, the first cases of influenza were seen in our 

 metropohs; "all London," in Watson's words, "being 

 smitten with it on that and the following day." On 

 this same fateful day Watson records that a ship ap- 

 proaching the Devonshire coast was suddenly smitten 

 with influenza, and within half an hour forty men 

 were ill. In 1836 another epidemic appeared in 

 Russia ; and in January 1837, Berlin and London 

 were almost simultaneously attacked. Ten years 

 later, in 1847, ^the last great epidemic raged in 

 our own country, and was very severe in November, 

 having been observed in Petersburg in March, and having 

 prevailed very generally all over Europe. 



Some of these epidemics are believed to have travelled 

 still further westward, to America ; but the evidence on 

 this point seems less conclusive. Without entering on 

 further historical details, and without speculating on the 

 nature of the disease, we may conclude that these 

 broad facts are enough to show that a more or less rapid 

 extension from east to west has been the rule in most of 

 the great European epidemics of influenza ; and that 

 therefore its successive appearance in Russia, Germany, 

 and France, makes its extension to our own country in the 

 highest degree probable. 



There are, it is true, certain facts on the other side, but 

 they appear much less cogent. Since our last great visita- 

 tion, certain epidemics of influenza have been recorded 

 on the Continent which have not reached our shores. 

 One was that of Paris in 1866-67 ; another at Berlin in 

 1874-75, of ^ disease described by the Gg-man doctors 

 as influenza, and of great severity, affecting all classes of 

 society. But in all epidemic and even contagious 

 diseases there are outbreaks which seem to be self-limited 

 from the first, showing no tendency to spread. This has 

 been notably the case with plague and cholera. On the 

 other hand, when an epidemic shows an expansive and 

 progressive character, it is impossible to predict the extent 

 to which it may spread. And the present epidemic, it 

 must be confessed, appears to have this expansive 

 character. 



Many interesting points are suggested by this historical 

 retrospect. What is the meaning of the westward spread 

 of influenza, of cholera, and other diseases? Is it a uni- 

 versal law ? To this it must be said, that it is by no 

 means the universal law even with influenza, which has 

 spread through other parts of the world in every kind of 

 direction, but it does seem to hold good for Europe, at 

 least in the northern parts. The significance of this law, 



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