Deep sea fishermen and keepers in lighthouses and on lightships frequently have no communication with land for a long time. The careful official investigations which were made in England have shown that in 1889-1890, among 415 residents in the 51 lightships and in 20 lighthouses, upon the English coast, influenza occurred at only four places and affected only eight persons, and in every one of these cases direct communication with the infected coast could be definitely proved. Among the workmen upon the Northeast Sea canal only those were attacked who lived in Rendsburg. Those living outside in barracks were unaffected by the disease. The 438 lead miners of Rookhope, in a lonely valley in Durham, were quite exempt from influenza during the three epidemics (from 1889-1892).
The prevalent view at the beginning of the pandemic of 1889 of the miasmatic, that is to say, of the aerogenous nature and aerodromic transmission of influenza, raised, among others, the question whether those engaged in open air occupations were earlier and more intensely attacked by influenza. Several of the older physicians (Bianchi, 1712, and others) were of this opinion. (The question itself is illogical, for the air from outside is continuously, although slowly, streaming through our rooms and dwellings, which are certainly not germ proof.) On the contrary, the air in houses with influenza patients was probably far more laden with the air borne germs than the air outside. Occasionally it seemed as if those whose occupations involved remaining for a long time in the open air, such as postal and railroad officials, and among these especially the traveling clerks, were early and severely affected by influenza. But in opposition to all these partly statistically proved statements, there are others from other places to show that residence in the open conferred a conspicuous immunity. Here statistics directly contradicted each other. Moreover, the well arranged statistics regarding the incidence of influenza among the officials and servants of the various state railways shows that the personnel in the offices was oftener affected earlier and more severely than those on outdoor duty.
Quite a number of occupations were thought to confer immunity against influenza, so that workers in glass, coke, smelting ovens, chlorinated lime, petroleum, tobacco, cement, sulphuric acid, creolin factories, and tanneries were thought to be exceptionally exempt. But against all these statements others were brought which showed that these occupations did not confer immunity, so that we arrive at the following conclusion: Occupation and social positions have an influence on the disease incidence only in so far as certain occupations and conditions of life offer greater or lesser opportunity for intercommunication.
The differences occasionally noted in the frequency of the disease in different races of men, as, for instance, between natives and Europeans, depend undoubtedly upon other circumstances than race (communication, living, sanitation, etc.).