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Table IX
Incidence of B. Influenzæ in Normal Men Contrasted With That in Early Cases of Influenza as Determined by Multiple Cultures from Nose, Throat, and Sputum
DATE	PLACE	GROUP	NUMBER EXAMINED	PER CENT SHOWING B. INFLUENZÆ
NOSE	THROAT	SPUTUM DIRECT CULTURE	SPUTUM MOUSE INOCULATION	BY MULTIPLE CULTURES
Nov. 12	Hot Springs, Ark.	Normal draft men assembled to entrain for camp	50	0	0	0	22	22
				(4 cultures only)	(31 cultures only)
Nov. 25	Camp Pike	Normal men; 12 had influenza during the epidemic	26	38.6	50	34.6	50	80.8
Dec. 10	Camp Pike	Normal men; 12 had influenza during the epidemic	25	48	52	24	68	88
Oct. 10 and Nov. 19	Camp Pike	Patients with influenza in Base Hos.	28	21.4	50	60.7	78.6	100

Summary of the results obtained in normal men shows that the incidence of B. influenzæ in normal individuals from isolated communities or in groups free from respiratory diseases prior to the occurrence of the fall epidemic was relatively low, namely, 10 to 20 per cent; that in observations made before the fall epidemic in groups in which “bronchitis” and pneumonia were fairly prevalent, B. influenzæ was found much more frequently, namely, in 25 to 50 per cent of the cases; and that in groups studied at intervals during the epidemic the incidence of B. influenzæ rapidly rose, reaching 85 per cent at the end of the epidemic. In contrast with this, B. influenzæ was found in 100 per cent of cases of influenza without reference to the time at which they occurred during the epidemic. It is obvious that the high percentage of normal men carrying B. influenzæ found at the end of the epidemic can depend only on the wide dissemination of B. influenzæ that must occur during epidemic times.

Bacillus Influenzæ in Measles.—Since the presence of B. influenzæ in other diseases than influenza has been advanced as an argument against its causal relationship to influenza, an extensive study of the incidence of B. influenzæ in the throats of measles patients was made during the period of the epidemic of influenza at Camp Pike from September 10 to October 20. In all a total of 830 throat cultures in 487 cases of measles were made, many cases being cultured repeatedly at weekly intervals. The results have been condensed as far as possible and are presented in Tables X, XI, XII.

Table X
Incidence of B. Influenzæ in 400 Consecutive Cases of Measles as Determined by Throat Culture at Time of Admission to the Base Hospital
DATE	NUMBER OF CASES	B. INFLUENZA FOUND
NUMBER	PER CENT
Sept. 16–Oct. 4	100	27	27
Oct. 4–Oct. 10	100	32	32
Oct. 10–Oct. 15	100	32	32
Oct. 15–Oct. 19	100	48	48

The prevalence of B. influenzæ in cases of measles during the period of the influenza epidemic corresponded very closely with that found in normal individuals under similar circumstances. The increasing proportion of cases carrying B. influenzæ as the epidemic of influenza advanced is further evidence of the wide dissemination of the organism during the epidemic.

Table XI
Incidence of B. Influenzæ in 830 Throat Cultures in 487 Cases of Measles; Cultures Repeated at Weekly Intervals
DATE	NUMBER OF CASES	B. INFLUENZA FOUND
NUMBER	PER CENT
Sept. 10–15	47	15	31.9
Sept. 16–29	106	33	31.1
Sept. 30–Oct. 6	122	38	31.1
Oct. 7–13	235	96	40.8
Oct. 14–20	320	157	49.1
Total	830	339	40.8

Table XII
Total Number of B. Influenzæ Carriers Among 223 Cases of Measles as Determined by Repeated Throat Cultures at Weekly Intervals after Admission to Hospital
TIMES CULTURED	NUMBER OF CASES	NUMBER OF CULTURES	B. INFLUENZÆ FOUND	TOTAL CARRIERS IN ONE OR MORE CULTURES
NUMBER	PER CENT	NUMBER	PER CENT
2	129	1st	37	28.7	82	63.6
		2nd	63	48.8
3	69	1st	20	28.9	52	75.4
		2nd	31	44.9
		3rd	33	47.8
4	25	1st	6	24	21	84.0
		2nd	10	40
		3rd	13	52
		4th	14	56

It is evident from the figures presented in Table XII that a large percentage of the measles cases studied were at one time or another carriers of B. influenzæ. In consideration of this fact, it must be borne in mind that all these cases were cultured during the period when the influenza epidemic was at its height and that many of these cases had influenza while in the hospital for measles. No data are available as to the exact number, since a definite diagnosis of influenza could hardly be made during the acute stage of measles. It is probable that approximately 25 per cent developed influenza, since that was the incidence of influenza in the total population of Camp Pike. The consistent increase in the percentage of influenza carriers clearly demonstrates that this was due to wide dissemination of B. influenzæ with the progress of the epidemic. Another point of exceeding interest is that the percentage of measles cases carrying B. influenzæ in the throat was lowest during the acute stage of the disease and increased during convalescence. This is in direct contrast with the results found in cases of influenza where the number of cases carrying B. influenzæ in the throat was highest during the acute stage and rapidly diminished in uncomplicated cases with the onset of convalescence.

Summary.—Multiple cultures made simultaneously from the nose, throat and lower respiratory tract showed that B. influenzæ was invariably present in all cases of influenza from the onset of the disease. Not only was B. influenzæ present in all cases, but it was frequently present in predominant numbers, sometimes in nearly pure culture. In the majority of cases that went on to rapid recovery without the development of an extensive bronchitis or complicating pneumonia, the predominance of B. influenzæ over other organisms rapidly diminished coincident with onset of convalescence. Many cases, however, continued to carry B. influenzæ in large numbers in the throat throughout convalescence. No data on the possible duration of the carrier state have been obtained. By the culture methods employed no other organism has been found that would suggest any etiologic relationship to the disease. The two organisms most frequently associated with B. influenzæ in postinfluenzal pneumonias, pneumococcus and S. hemolyticus, have not differed in their incidence in early uncomplicated cases of influenza from that found in normal individuals.

The incidence of B. influenzæ in normal men, in different groups studied, has varied between 11.1 and 88 per cent. This wide variation has depended upon the prevalence of respiratory diseases, more particularly influenza, in the groups studied and the opportunity thereby offered for the wide dissemination of B. influenza. With the progress of the epidemic, the number of normal men carrying B. influenzæ has steadily increased until it reached its maximum at the end of the epidemic.

The incidence of B. influenzæ in cases of measles studied during the epidemic of influenza has been relatively high though never equaling that found in cases of influenza. As in normal men, the incidence in cases of measles has steadily increased during the period of the epidemic. Repeated throat cultures at weekly intervals in cases of measles have shown that approximately 80 per cent became temporary carriers of B. influenzæ at one time or another during the period of the epidemic. Many of these cases had influenza during the time that they were in the hospital. The carrier state in cases of measles was found to bear no relation to the acute stage of the disease since the number of carriers at the time of admission to the hospital was considerably lower than that found during convalescence as determined by repeated cultures in the same cases.