Hirsch and McKinney report that an epidemic of unusual virulence swept with great rapidity through several organizations in Camp Grant between September 21, 1918, and October 18, 1918. During this time 9,037 patients were admitted to the Base Hospital, representing about one-fourth of the strength of the camp, and of these, 26 per cent. developed pneumonia. About 11 per cent. of the total admissions or 43 per cent. of the total cases of pneumonia died.
Referring to the report of Howard and Love, we quote as follows: “It is probable that practically all susceptible human material in infected camps suffered from an attack of the disease during the continuance of the epidemic. The records from various camps indicate that from 15 to 40 per cent. of commands suffered from an attack of the disease. These records, as previously stated, do not indicate in full the true incidence of the disease. Certain good results were accomplished in some camps by the application of effective and early isolation of patients and suspects and other measures generally recognized as of value. It was sometimes possible to retard the progress of the epidemic and cause it to be spread over a longer period of time. The epidemic thus became less explosive in character, and fewer people were under treatment at the same time. It was possible to take better care of the sick and thus reduce the incidence of and deaths from complicating pneumonia. It has not been shown that such measures accomplished reduction in the absolute number of cases of influenza occurring in one command as compared with another.
“The ‘cantonment’ group of camps gave a much higher death rate from influenza and its complications than the ‘tent’ camp or ‘departmental’ group. At first glance it would appear that the different housing conditions and the more marked overcrowding in cantonments at the time would fully account for this divergence. Closer study, however, leads to the conclusion that geographical location was a factor of equal or greater importance. It is well known that the disease was most virulent and fatal in the northern, eastern and middle west states, a district in which cantonments predominated. In the southern and Pacific coast states, where the most of the tent camps were located, a milder type of the disease prevailed, with fewer resultant fatalities. Camp Lewis, Washington, and Camp Gordon, Georgia (both cantonments), had relatively low death rates, approximating those in nearby tent camps. On the other hand, Camp Syracuse, New York, and Camp Colt, Pennsylvania (both tent camps), suffered severely and reported death rates approximating those of cantonments in the same geographical district.”
Three waves of influenza are reported by Stanley at San Quentin Prison. During the early wave it was estimated that over 500 of the 1,900 men in the prison population were ill. The wave lasted for a little over two weeks. In the second epidemic there were 69 cases in all, ten per cent. of which developed pneumonia, with two deaths. There were fewer ambulatory cases than in the first. Three and seven-tenths per cent. of the population was attacked in the second epidemic, as compared with 27 per cent. in the first. In the third epidemic there were 59 cases, with no pneumonia and no deaths.
Hernando estimates that in the Philippine Islands, 40 per cent. of the total population of 7,000,000 was stricken with the disease. The epidemic began in June, although it did not become severe until October. The group of ages that suffered most were those between ten and twenty-nine years. Hernando does not believe that the disease was imported because cases were reported before ships arrived from infected countries. After the importation of cases from elsewhere the disease assumed the more severe form.
Armstrong, in reporting a survey of 700 influenza convalescents in Framingham, Mass., remarked that 16 per cent. of the entire population were infected with influenza. Reeks, in a house survey in New Britain, Connecticut, found from among 2,757 persons that the morbidity rate reached 234 per thousand. Dr. Niven found in his block census in Manchester, England, that of 4,721 individuals, 1,108 (25 per cent.) had developed the disease. Fourteen and eight-tenths per cent. of the population were attacked in the summer and 10.4 per cent. during the autumn and winter.
Frost found in his survey of 130,033 individuals that the percentage of the population attacked varied from 15 per cent. in Louisville, Ky., to 53.3 per cent. in San Antonio, Texas, the aggregate for the whole group being about 28 per cent. He remarks that this agrees with scattered observations in the first phase of the 1889–1890 epidemic, when the attack rate seems to have varied within these limits. In five of the localities studied, geographically widely separated, the incidence rate varied only within a narrow limit, from 200 to 250 per thousand. Variations in attack rate showed no apparent consistent relation to geographic location or size of community, or to the rapidity of development of the epidemic.
In a house-to-house survey of 10,000 individuals in Boston the author found that in the winter of 1918–19, 19.71 per cent., or one-fifth of the entire population had developed the disease. It should be pointed out that while the standards used in this survey are entirely comparable to those used by Frost, the author has, contrary to Frost’s method, not included in his group of positive cases those classified as “doubtful.” This would raise the total incidence to a certain extent, but we feel convinced that by omitting the doubtful cases we have approached nearer to a correct picture of the epidemic as it actually occurred. As will be seen from Chart XVI there was no great variation in the different districts studied, with the exception of Districts IV and V. Districts I, II and III were in the tenement section of the city, while District VI was in one of the finest residential parts of Brookline. Districts IV and V were midway between these two extremes as regards economic and sanitary status, as well as extent of crowding. The lowest incidence was in the Irish tenement district. The highest in a middle class Jewish population.
CHART XV.
