May 30, 1890.] 



SCIENCE. 



329 



The ratio of mortality under this estimate is 1 in 83 and a frac- 

 tion (^fff§fi=83.78). But in this comparison we have ignored 

 some very important factors wliich are in favor of Dr. Fi-eire's 

 statistics. A large number of the deaths, no doubt, occurred 

 among strangers who did not belong to the population of the city, 

 and especially among the sailors on foreign vessels arriving dur- 

 ing the epidemic, who are commonly sent to the Jurajuba Hos- 

 pital when taken sick. On the other hand, we have no definite 

 information as to the precise date when the vaccinations were 

 practised, and no data with reference to the exposure before and 

 after vaccination. In the statistics of previous years a very con- 

 siderable number of persons were vaccinated after the epidemic 

 had terminated ; that is, persons who had passed through the 

 epidemic season without contracting the disease were vaccinated, 

 and counted among those supposed to be protected from an at- 

 tack by this proceauie. Evidently, the later in the epidemic the 

 vaccinations were practised, the less value can be accorded to the 

 subsequent exposure as a test of protection. Previous exposure 

 without being taken sick is, on the contrary, evidence of com- 

 parative insusceptibility. To put those vaccinated on the same 

 footing with the 200,000 of the population of Rio with whom we 

 have compared them, they should have been vaccinated at the 

 outset and exposed in the infected city throughout the epidemic 

 season. How many were vaccinated when the epidemic had 

 commenced to decline, or after it had practically terminated? How 

 many left the city soon after being vaccinated? These are ques- 

 tions we cannot answer for 1889; but the facts with reference to 

 1884, 1885, and 1886 are given in my published report heretofore 

 referred to, some extracts from which I beg leave to quote. Re- 

 ferring to the year 18s5, I say, — 



"Dr. Freire has omitted to state one very important fact with 

 reference to vaccinations practised during the period included in 

 this tabular statement. The date of vaccinations is not given. 

 Fortunately, I am able to supply this omission from his journal 

 containing the names of the vaccinated, which he kindly placed 

 in my bands during my stay in Rio. I find from this record that 

 the inoculations were practised as follows: — 



January 392 



February 34J 



Marcli 611 



April 139 



May 273 



June 813 



July 481 



"Now, it is well known that June and July are inonths during 

 which yellow-fever does not prevail in Rio, and that, in fact, the 

 month of May furnishes as a rule but few cases. 



"The exposure even in an epidemic year amounts to very little 

 during the months of May, June, and July, and may be consid- 

 ered practically nil in a year like 1885, when the whole mortality 

 was only 378 in a city of 400,000 inhabitants. But Dr. Freire has 

 included in his list 1,294 persons who were vaccinated during the 

 healthy winter months of June and July, and who presumably had 

 beenexposedduring the preceding comparatively unhealthy months 

 of January, February, March, and April. If these 1,294 individuals 

 were protected from an attack of yellow-fever by the inoculation 

 practised in June or July, what protected them from being at- 

 tacked during the preceding epidemic season? We must insist 

 upon excluding these 1,294 persons from consideration during the 

 year 1885, to which the report under review relates, and we think 

 that it would be quite proper also to exclude those inoculated 

 during the month of May, but will not insist upon this point. 

 We have, then, to consider the value of the evidence oflfered by 

 Dr. Freire as regards 1,757 inoculated persons, instead of 3,051 in- 

 cluded by him in his statistics for the year. 



"Again I find, that in 1886, as in 1885, Dr. Freire has included 

 in his statistics a large number of persons who were vaccinated 

 after the termination of the epidemic, and whose expusure was but 

 little greater than that of the 1,476 imaginary persons who must 

 be added to his list in order to give the mortality of 1 per 1,000. 



"Dr. Freire has not given us the date of his vaccinations in his 

 elaborate presentation of his statistical results, but I find from his 



manuscript record that they were distributed throughout the year 

 as follows (I place in parallel column the figures showing the total 

 mortality from yellow-fever during the period) : — 



Vaccinations. 



Total Deaths 



from 

 YeDow-Pever. 



January. . , 

 February. 



Marcb 



April 



May 



June 



July 



August — 



"This table shows that during the epidemic period, from Jan. 1 

 to April 30, there were 880 vaccinations, and during the same 

 period 936 deaths occurred from yellow- fever; while during the 

 months of May, June, July, and August, when the total mortal- 

 ity was but 77, the number of vaccinations was 1,026: i.e., a ma- 

 jority of the vaccinations were practised after the epidemic sea- 

 son was over, and upon persons who, no doubt, had for the most 

 part passed through the epidemic season without contracting the 

 disease. 



"We turn now to the age of the vaccinated persons. Dr. Freire 

 says, in his report first quoted, that the great'-r proportion of the 

 deaths is comprised between one and thirty years. This is, then, 

 the period most favorable for the development of yellow-fever. 

 Now, it will be seen that among the number vaccinated, which 

 we give in the second part of our statistics, 2,6i4 individuals are 

 comprised in this period. But Dr. Freire has elsewhere shown 

 us that the age which gives the greatest mortality is from twen- 

 ty-one to thirty years. Let us then see what proportion of the 

 vaccinated are included in these limits. Reference to his tables 

 shows the deaths between twenty-one and thirty years of age to 

 have constituted 39 per cent of the entire mortality, while only 15 

 per cent of the vaccinated fell within these limits of age. On the 

 other hand, 43 per cent of the vaccinated were less than ten years 

 of age, while the mortality for this period was only 12.5 per cent 

 of the entire mortality. We note, also, that a large number of 

 the children vaccinated were infants below two years of age. 



"In Dr. Freire's report under review, he says, on p. 7, 'We in- 

 clude in these figures all the vaccinated during the two previous 

 years who liave been carefully observed during the epidemic sea- 

 son.' 



"That portion of the sentence which I have italicized surprises 

 me exceedingly. From what has been said, it will be seen that 

 a careful observation of the floating population of the corligos, in 

 which most of the vaccinated persons resided, would be practi- 

 cally impossible, even with a large force of inspectors at com- 

 mand. 



"Dr. Freire himself did not find time to make fhe vaccinations 

 among these poor people of the cortigos, but delegated this work 

 to certain apothecaries. One of these, Mr. Telles, informed me 

 that he had himself vaccinated between three and four thousand 

 persons. He also communicated the startling information that 

 none of those inoculated with the 'attenuated microbe' of yellow- 

 fever had contracted small-pox during the recent epidemic in Rio, 

 leaving me to infer that the vaccine was a protection against both 

 diseases. This intelligent(?) apothecary, a mulatto, recorded a 

 large portion of the statistics which Dr. Freire has tabulated." 



I have said enough to show Dr. Freire's method of manufac- 

 turing statistics, and must refer the reader who desires fuller de- 

 tails to my published report. George M. Sternberg, M.D. 



