An avirulent live Pasteurella multocida vaccine for drinking water and aerosol administration against turkey cholera.

A naturally avirulent isolant of Pasteurella multocida (Heddleston sero-type 3) was investigated as a seed strain for the development of a live vaccine against turkey pasteurellosis. Laboratory trials showed that when given in aerosol form at a dosage of 5 x 10(8) c.f.u. per m(2), of barn floor, the vaccine produced satisfactory protection against both homologous and heterologous serotypes challenge administered by aerosol. Likewise, turkeys vaccinated once, twice or three times, and challenged at various time intervals were protected for over 20 weeks. The vaccine strain could be recovered from the lungs for a period of 6 days following aerosol vaccination.