Читать книгу Epidemic Respiratory Disease. The pneumonias and other infections of the repiratory tract accompanying influenza and measles онлайн

34 страница из 67

In a series of animal experiments carried out by this commission recorded in an appendix to this report, sixteen-hour cultures of B. influenzæ freshly isolated from early cases of influenza were demonstrated to be pathogenic for monkeys, both by inoculation of the nasal and pharyngeal mucosa and by intratracheal injection. Monkeys so inoculated developed coryza, epistaxis, tracheitis, bronchitis, and extreme prostration. Experiments with forty-eight-hour cultures of strains preserved by subculture during from ten to fifteen days failed to demonstrate pathogenicity for monkeys. Proof that these monkeys had influenza can depend only upon the demonstration that they suffered with a disease having the clinical character and pathologic lesions of influenza.

The reported failure to produce influenza in man by direct inoculation with freshly isolated cultures of B. influenzæ in experiments conducted on volunteers by the United States Public Health Service^[27] at Gallops Island, Boston, is interesting, but would seem to lack definite significance since attempts to transmit the disease from man to man by direct contact also failed. Since all the subjects of these experiments had been previously exposed to influenza during the epidemic, 30 per cent actually having contracted the disease, it would seem probable that the remaining 70 per cent were only very slightly if at all susceptible. It is noteworthy that the attack rate of influenza in most army groups was approximately 20 to 30 per cent during the epidemic, the remaining 70 to 80 per cent failing to contract the disease though equally exposed. No other explanation presents itself except that influenza is no longer transmissible when clinical symptoms have appeared.