13 St. Louis Courier of Med., Sept., 1879.

14 Annales de Gynécologie, May, 1879.

All ages are susceptible to the measles poison, and the apparent exemption enjoyed by adults is due to the fact that most grown-up people have already suffered the disease in childhood; but in Panum's epidemic, mentioned above, it was discovered that nearly all who had not had measles elsewhere, or were not old enough to have been exposed at the last visitation, sixty-five years before, acquired the affection regardless of age. It is quite probable, however, that the law of decrease of susceptibility with age holds good for measles as well as for variola, etc., but to a less degree. It will therefore be seen that measles is not essentially a disease of childhood. Although there is no special limit to the susceptibility of rubeola at one extreme of life, it would seem to be quite well established that it is much modified at the other—namely, that infants under six months are rarely attacked. This latter fact is conceded by individual experience, by the records of epidemics, and by the testimony of most observers.15

15 On the other hand, as quoted by Forchheimer (loc. cit.), H. C. Fox publishes some tables which show that for England and London a much larger number of young children are attacked by measles than other statistics would lead us to believe.

England. London.
Males. Females. Males. Females.
Under one year 3022 2530 3571 2987
One and under two years 6086 5825 8630 8050
Two and under three years 3178 3255 4683 4757
Three and under four years 1730 1851 2594 2620
Four and under five years 980 1028 1358 1466
Five and under ten years 255 278 301 316
Ten and under fifteen years 29 38 24 32
Fifteen and under twenty years 9 13 9 11
Twenty and under twenty-five years 7 9 5 7
Twenty-five and under thirty-five years 5 8 5 7
Thirty-five and under forty-five years 3 5 2 3

Even sucklings do not enjoy a complete immunity from measles. Steiner16 states that he has met with it in children only four or five weeks old. Monti has recorded ten cases of rubeola in children under two months of age. A case is reported by Kunze where a mother in the stage of efflorescence gave birth to a child, which contracted the disease five days afterward. Quite a number of cases of congenital measles have been put on record from time to time; but Thomas, after a careful investigation, says that he has been able to discover but six authentic accounts of such occurrences.17 That children born to mothers suffering at the time of parturition from measles may yet escape it themselves is proven by the cases of Nelson and Gautier mentioned above. Whether a pregnant woman attacked by measles transmits the disease to the foetus in utero, thereby securing immunity from it in after life, is a question difficult of decision, especially as we have not yet been able to decide this same inquiry, with infinitely better opportunities, for vaccinia.18

16 Compendium of Children's Diseases, N.Y., 1875, p. 396.

17 I believe that, under certain circumstances, the erythema papulatum of the new-born is often mistaken for measles.

18 See experiments of Burckhardt, Rickett, Gart, and others, quoted in Hardaway's Essentials of Vaccination, p. 38.

There is no good reason to believe that sex is of much importance in establishing a predisposition to measles, although the statement has been repeatedly made that males are more frequently attacked than females. Fox's statistics show a slight preponderance in favor of the male sex; but a careful examination of accessible statistics proves, as would be expected, that this degree of susceptibility varies at different times in obedience to circumstances not readily understood.