Protection against Pasteurella pneumotropica during infection with Angiostrongylus cantonensis.

Lung infections of specific-pathogen-free rats were studied to determine cross-immunity between infections with Pasteurella pneumotropica and Angiostrongylus cantonensis. Rats were found to have differences in mortality due to pneumonic infections with P pneumotropica and A cantonensis and to coinfections of P pneumotropica and A cantonensis. Single infections of P pneumotropica were not dosage-dependent in their lethality for specific-pathogen-free rats. The mortality of coinfection with P pneumotropica and A cantonensis was significantly lower than that of a monoinfection with P pneumotropica, demonstrating a cross-protective phenomenon.