Conditions Favouring Diphtheria

The circumstances of the great and sudden explosion of diphtheria in 1858 and 1859 are as likely as any to throw light on the causes or determining conditions of the disease. Those two years were remarkable for the Thames running so low in summer as to give out a stench, which was thought to forebode much fever[1379]. The expected epidemic of fever did not come; on the contrary the fever deaths in London were much lower than usual in 1858 and 1859, and, to judge from the few admissions of each kind to the London Fever Hospital, enteric fever declined as well as typhus[1380]. It was diphtheria that came. The lowness of the rivers was due to a succession of years with rainfall below the average:

Low rainfall High rainfall

1855 21·1 inches 1865 29·0 inches

1856 22·2 " 1866 30·7 "

1857 21·4 " 1867 28·4 "

1858 17·8 " 1868 25·2 "

1859 25·9 " 1869 24·0 "

Average 21·7 " Average 27·4 "

The low state of the rivers was an index of a low level of the ground-water. If diphtheria is to be included among the infections that have the habitat of their virus in the soil, it will probably be found to be affected by irregularities in the movements of the subsoil water. A series of observations have been made which seem to favour that hypothesis.

At Maidstone in each of the three years 1885, 1886 and 1887, the ground-water rose with the greatest regularity and steadiness to its highest point towards the end of the first quarter of the year, and fell with equal steadiness to its lowest point in the autumn. During two of the years there was little diphtheria, and in one of them none. But, in the next two years, 1888 and 1889, “the levels of the ground-water oscillated to and fro with unwonted frequence,” having several maxima in 1888, and a somewhat uniform high level all through 1889; and during those two years there was a severe outbreak of diphtheria, as well as an excessive number of deaths registered as “croup[1381].”

The relationship with the ground-water, if any, will probably be found to be more than ordinarily complex; but some connexion is indicated by the remarkable selection of the Fen country of Lincolnshire in 1858. Among the 18th century observations, it was remarked in New England in 1735-36 that the throat distemper was worst near lakes or rivers, as at Newbury Falls, Hampton Falls, and the like. The ill-reputed “Kidderminster sore throat,” was associated with the low situation of weavers’ houses in the valley of the Stour, subject to inundations. Practitioners in many parts of England and Scotland have suspected an association with water, even if it were only a mill dam, in the more recent prevalence of diphtheria[1382].

Diphtheria has affinities in its pathological nature with enteric fever on the one hand and with scarlatina on the other. The process in the throat and pharynx is comparable to the typhoid process in the ileum, which is often a truly diphtheritic process in the second half of the fever[1383]. The affinities to scarlatina are shown best of all in the real ambiguity of diagnosis in some whole epidemics of the 18th century, if not also in the great epidemics of garrotillo in the 16th and 17th centuries. Another singular affinity both to scarlatina and to enteric fever lies in the fact that diphtheria, as well as each of these, has been distributed in milk from some particular dairy, and that contamination of the milk by the products of disease upon the cows’ teats has been found to be the relevant thing both for the scarlatina and the diphtheria[1384]. Again, whatever suspicion pertains to slaughter-houses or animal offal for the production of a scarlatinal miasm, pertains to them also for the diphtherial. With such more or less real affinities in the pathology and etiology, it may be made a question whether the recent increase of the death-rate by diphtheria in London and some other places has depended, as if in the way of correlation, upon the decrease in the death-rates of scarlatina and of enteric fever[1385]. Diphtheria is perhaps the most obscure and complex of all the infective diseases in its causes and favouring conditions. A certain explanation may seem to suit one outbreak and be wholly irrelevant for another. More particularly there have been innumerable cases for which insanitary surroundings cannot be alleged in any ordinary meaning of the term.