Time course investigation of infection with a low virulent Pasteurella multocida strain in normal and immune-suppressed 12 week-old free range chickens

Citation:
Mbuthia PG, Njagi LW, Nyaga PN, Bebora LC. "Time course investigation of infection with a low virulent Pasteurella multocida strain in normal and immune-suppressed 12 week-old free range chickens.". 2011;10.

Abstract:

Time course investigation of infection with a low virulent Pasteurella multocida strain in normal and immune-suppressed 12 week-old free range chickens

P. G. Mbuthiaa, L. W. Njagia, P. N. Nyagaa, L. C. Beboraa, U. Mingab, Jens Peter Christensenc & J. E. Olsenc*

Date of publication: DOI:10.1080/03079457.2011.623298; Available online: 15 Sep 2011
Avian Pathology
Abstract
Twelve week old indigenous chickens, either immune-suppressed using dexamethasone (IS) or non-immune-suppressed (NIS), were challenged with a low virulent strain, Pasteurella multocida strain NCTC 10322T and developed clinical signs and pathological lesions typical of chronic fowl cholera. NIS birds demonstrated much more severe signs of fowl cholera than IS birds. With few exceptions, signs recorded in IS and NIS birds were of the same types, but significantly milder in the IS birds, indicating that immune-suppression does not change the course of infection, but rather the severity of signs in fowl cholera.
P. multocida signals by fluorescent in situ hybridization (FISH) were observed between 1 hr and 14 days in lungs, trachea, air sacs, liver, spleen, bursa of Fabricius and caecal tonsils, while signals from other organs mostly were observed after 24 hours. More organs had FISH signals in NIS than in IS-birds and at higher frequency per organ. Many organs were positive by FISH even 14 days post infection, and it is suggested that these organs may be likely places for long term carriage of P. multocida following infection.
This study has demonstrated the spread of P. multocida in different tissues in chickens and distribution of lesions associated with chronic fowl cholera, and pointed to a decrease of pathology in immune-suppressed birds. Since dexamethasone mostly affects heterophils, the study suggests that these cells play a role in the development of lesions associated with chronic fowl cholera in chickens.

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