Perinatal lamb mortality in Western Australia: 5. Vibrionic infection

Area of Science:

• Veterinary Pathology
• Animal Microbiology
• Epizootiology

Background:

• Vibrionic abortion is a significant cause of ovine reproductive loss.
• Campylobacter fetus subsp. intestinalis is a primary pathogen responsible for ovine abortions.
• Understanding the epidemiology and pathology is crucial for disease management.

Purpose of the Study:

• To document the incidence and characteristics of vibrionic abortion in Western Australian sheep.
• To analyze the mortality patterns and gross pathological findings in infected lambs.
• To identify the causative agent, Campylobacter fetus subsp. intestinalis, and its association with specific lesions.

Main Methods:

• Retrospective analysis of diagnosed cases of vibrionic abortion in sheep between 1963-1965.
• Examination of post-mortem records, including time-of-death and gross lesions.
• Bacteriological isolation of Campylobacter fetus subsp. intestinalis from affected lambs.

Main Results:

• 48 diagnoses of vibrionic abortion were recorded, with 3 cases co-infected with other pathogens.
• Lamb mortality occurred ante-parturient (50.5%), parturient (13.2%), and post-parturient (36.3%).
• Common gross lesions included subcutaneous edema, serous cavity effusions, and characteristic liver foci (37.4%). Campylobacter fetus subsp. intestinalis was isolated from lambs with liver lesions and starvation signs.

Conclusions:

• Vibrionic abortion posed a substantial threat to lamb survival in Western Australia during the study period.
• The pathogen, Campylobacter fetus subsp. intestinalis, was confirmed as the causative agent, associated with specific pathological changes.
• Outbreaks occurred under diverse environmental conditions, including hot semi-arid regions, highlighting the need for targeted control strategies.