Study on the prevalence ofPasteurella multocida carriers in slaughtered cattle and relationship with their immunity status at Ahvaz abattoir

This study was carried out on 250 slaughtered cattle at ahvaz abattoir in khouzestanprovince oflran to investigate the occurrenceofpasteurella multocida carriersand relationshipwith their immunity status. nasopharyngeal swabs and 10 ml blood samples were takenimmediately after slaughter. the swabs were streaked on 5%sheep blood agar plates. culturesowere incubated at 37 c for 24h and the plates were examined for colonies resembling p.multocida, suspicious colonies were further subcultivated and examined microscopically andbiochemically. the isolates were serotyped serologically and their pathogenicity in mice wascarried out. sera samples were tested for the presence of antibody against p. multocida byindirect haemagglutination (lha) test and sera with a titer of ~1:16were considered as positive.p. multocida was isolated from the nasopharynx of 6 (2.4%) out of 247 healthy cattle examined.there was no relation between infectionand sexorage. all of6 isolates belonged to type b. theywere pathogenic for mice and caused death in injected mice within less than 24h after injection.indirect haemagglutlnatlon test revealed the titers of ~1:16 of p. multocida antibody in 212(84.8%) cattle. among 6 cattle recognized as the carriers of p. multocida, 5 were positiveserologically and 2, 2, and one of them had titers 1: 128, 1: 64,and 1: 32, respectively.