INCUBATION.
Great discrepancies occur in the statements of different observers, but inasmuch as each epidemic varies in severity, a severe type of the “Flu” may have a shorter incubative period than a mild type, and therefore taking the variations in type into consideration, may reconcile the differences. If Influenza was accompanied with a facial eruption or exanthem, this would materially assist in the determination of its Incubative period. In Hawaii, two to three days is the most frequent period of Incubation; it may vary, however, from 24 hours to 72 hours, even to five days; in these long incubative cases, headache, aching eyeballs, and great languor are the indicating signs, and those persons so affected succumb slowly and offer great resistance to the overpowering toxins of the Bacillus Influenzae.
The Immunity which a person may possess in one Epidemic and not in another, may be accounted for by assuming that each Epidemic may have a difference in the strain or the species of the Influenza bacillus.
SALIENT POINTS.
Period of Life. Most cases occur between 20 and 40 years.
In Schools. The older children are first attacked: open air schools are a positive, but not an absolute defense against Infection.
Indoor Schools. The ratio of prevalence amongst children of all ages is 40%.
Outdoor Schools. All ages, the ratio of prevalence is 10%.
Open Air Occupations. Such as workers in the fields, 12% are attacked.
Closed Rooms. Factory Operatives, 49% are attacked.