Studies on respiratory infection: II. The influence of aerosol particle size on infection of the guinea-pig with Pasteurella pestis

Abstract

The LD50 dose of Past. pestis is much greater when tested by the respiratory route than by subcutaneous challenge. This is probably due to trauma inflicted on the airborne particles.Two forms of plague, both originating in the respiratory tract of the guinea-pig, can develop according to the size of the particle containing Past. pestis presented to the host. Small particles initiate a broncho-pneumonia which leads to septicaemia and death. Large particles establish a septicaemia, and death results more quickly without the development of a pneumonia.Cross-infection to normal animals occurs irregularly when they are exposed to others developing plague by the respiratory route. Such incident is rare when the initially infected animals are exposed to large particles. Cross-infected animals suffer from the disease characteristic of exposure to large particles. Attempts to establish an epizootic by cross-respiratory infection were abortive, probably due, in some measure, to the type of disease developing in first cross-infections.