Abstract
Successful infection of animals with a virus recovered from influenza patients 1 laid the foundation for experimental study of the mode of transmission of this important respiratory disease. Intranasal instillation of influenza virus recovered from artificially infected air 2 proved air conveyance of the virus to be possible, and destruction of the air-suspended virus by ultraviolet irradiation raised hopes of environmental control of epidemic influenza by sanitary ventilation. Demonstration of air-borne influenzal infection of ferrets 3 and introduction of quantitative inhalation technics of inoculation 4 provided experimental means for study of air-borne influenza and air-borne superinfections which frequently complicate the pathologic and epidemiologic patterns.
The experiments to be presented have been conducted during the fall and winter of 1939-40 when other duties delayed the continuation of this study until a preliminary report seems desirable. Of the 25 experiments performed, employing some 1500 mice, protocols have been chosen to illustrate our interpretation of the observed phenomena. These results have been found reproducible in repeated tests, but the exploratory nature of the protocols did not adapt them to statistical summary.
Experimental. I. Air-borne Transmission of Influenza A Virus. Exposure of white mice to air which had been infected by droplet nuclei derived from a suspension of the virus of influenza A produces typical signs of the disease in these animals and causes death with sufficiently high concentration of the virus. All mice exposed 45 minutes to air infected by atomizing 1 g of a 10% suspension of mouse lung (infected with PR-8 5 or WS 1 strain) in 50 cubic feet of air died within 6 to 9 days. (Table I.) If one-tenth of this amount was used for the spray, 30% of the mice succumbed and the remaining animals harbored severe lung lesions when autopsied on the tenth day.
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