65 Loc. cit.
That bad hygienic conditions have much to do with the induction of the disease is shown by the records of Zurich and Berne, where the cases have been very numerous among the lower classes, who are hard worked, ill fed, and poorly housed. Possibly here other unknown causes may be at work, as the conditions which prevail in the Zurich canton are not unknown in other countries. In Ireland, where the peasants have poor food and wretched houses, the disease does not appear to be common. In the Montreal cases the subjects were chiefly of the upper or of the higher mechanic classes.
The age most subject to the disease is the adult period; cases are rare under twenty and over fifty. In Pye-Smith's table of 103 selected cases there were only 6 under fifteen years of age; 4 between fifteen and twenty; 29 between the twenty-first and thirtieth years; 26 cases between the thirty-first and fortieth years; 21 between the forty-first and fiftieth years; 13 between the fifty-first and sixtieth; and only 4 above sixty. The youngest case I have seen was in a girl of twenty, and oldest in a woman over sixty. The youngest case on record was at the fifth year.66
66 Quoted in Am. Journ. Med. Sci., Jan., 1885.
Sex.—If we exclude all cases in women directly connected with the puerperal state, primary idiopathic anæmia is more frequent in men than in women. Of the 16 Montreal cases, 4 were dependent upon parturition, and of the remainder, 9 were in men and only 3 in women. But most of the collected figures include the parturition cases, and the women are in excess; thus, of 93 cases from the Swiss clinics at Zurich and Berne, 67 were females. Eichorst's figures are 65 women and 30 men. Of 110 cases collected by Coupland, 56 were men and 54 women. In Pye-Smith's careful tabulation of 103 selected cases, 48 were men and 59 women.
As observed by Channing, Lebert, and Gusserow, pregnancy and parturition are important factors in the production of a grave form of anæmia. In the majority of cases the symptoms develop post-partum, often, but not necessarily, in consequence of loss of blood during delivery. Obstinate vomiting during pregnancy and prolonged lactation may bring about the same condition. Of 29 cases of this sort in Eichorst's table, in 19 the symptoms developed during pregnancy and in 10 after delivery.
Gastric and intestinal disturbance, dyspepsia, vomiting, and diarrhoea have occurred in a number of cases prior to the development of the anæmia.
In some instances loss of blood, chronic discharges, ulcers, or other sources of drain have been present.
In not a few cases there has been mental worry, grief, or fright. This has been specially noted by Wilks and Howard, and more recently by Curtin.67 It does not seem probable that malaria has any predisposing influence.
67 "Nervous Shock as a Cause of Pernicious Anæmia," Med. Times, Philada., April 4, 1885.