LABORATORY STUDIES AND PRELIMINARY FIELD-EVALUATION OF VACCINATION TRIALS AGAINST PASTEURELLOSIS IN DUCKS

Formalin-inactivated, alum-adsorbed broth bacterin of Pasteurella multocida A: 1 from ducks was tested in laboratory and field trials. An indirect haemagglutination (IHA) test using glutaraldehyde-fixed sheep erythrocytes sensitized with crude capsular polysaccharide was conducted on duck sera for humoral antibody levels. The highest ranges of IHA IA titres of sera from once and twice vaccinated docks were, respectively, 80-640 and 1 280-10 240 as aganist 0-40 from unvaccinated ducks. The IHA titres were significantly higher (P<0.001) for vaccinated over unvaccinated and twice over once vaccinated ducks and did not decrease significantly up to 94 day post-vaccination. Ducks vaccinated twice withstood homologous challenge with 1 740 cfu 70 days after second vaccination. Recovered ducks had IHA tubes of 10 240 to 20 480 and withstood future high challenge dose of 10(7) to 10(8) cfu. Pasteurellosis could not be recovered from these birds. The disease in ducks was controlled by regular vaccinations and zoo-sanitary measures.