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

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Theoretically, under the conditions outlined above, ideal opportunities have been provided for B. influenzæ to build up sufficient virulence to enable it to produce the pandemic of 1918–19. While it is thoroughly recognized that these considerations are in the main hypothetical, it is felt that they are by no means beyond the bounds of possibility, and for that reason are offered as suggestions worthy of further investigation.

It is, of course, perfectly possible on the basis of the observations presented still to regard B. influenzæ as a secondary invader which makes its appearance in all cases of influenza simultaneously with the onset of clinical symptoms. Final proof of its causal relationship to the disease must depend upon the production of influenza by experimental inoculation. Results hitherto obtained in attempts to produce the disease experimentally have been contradictory. Pfeiffer^[8] claimed to have produced a disease in monkeys in some respects resembling influenza by the intratracheal injection of freshly isolated cultures of B. influenzæ. Wollstein,^[19] in studies upon the pathogenicity of various strains, has shown that B. influenzæ is generally pathogenic for mice and guinea-pigs without respect to source or virulence for man. Pathogenicity for rabbits and monkeys, on the other hand, was possessed only by strains that were highly virulent for man. She furthermore pointed out that for successful animal experimentation, it is imperative that inoculations be carried out immediately after the isolation of the bacilli because they rapidly lose virulence by subculture on artificial media. It is felt that failure to appreciate these facts has been responsible for the often repeated statement that B. influenzæ is not pathogenic for animals.