Transmission of rat and guineapig Haemophilus spp. to mice and rats

Mice and rats, free from Pasteurellaceae, were exposed to Haemophilus spp. (V-factor dependent Pasteurellaceae) by housing in proximity to infected ra ts or guineapigs, and monitored by culture and enzyme-linked immunosorbent assay (ELISA) for cross infection. A minority of mice became infected when exposed to Haemophilus-infected rats but none when exposed to guineapigs. R ats were readily infected when exposed to Haemophilus-infected guineapigs o r rats. Although Pasteurellaceae infections are commonly considered as host specific, our data show that Haemophilus spp. can cross the species barrie r from rats to mice and from guineapigs to rats.