Chlamydophila abortus
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- Ovine enzootic abortion
- Especially in intensive systems
- Ewe lambs may acquire infection at birth and abort in their first pregnancy
- Pathogenesis:
- Infection via ingestion or inhalation causes a bacteraemia
- Bacteria localise in placenta and cause placentitis, leading to late abortion or premature weak lambs
- Necrosis of cotyledons and oedema of adjacent tissue, as well as dirty pink uterine discharge
- Aborted lambs well preserved
- Large numbers of chlamydiae shed in placenta and uterine discharges; survive in environment for several days
- Abortion rates may reach 30% in susceptible flock
- Ewes infected late in pregnancy may not abort, but may abort during the next pregnancy
- No other clinical signs in aborting ewes
- Fertility not impaired
- Transmission:
- Survival of elementary bodies in faeces and wild birds are a source of infection from one lambing season to the next
- Ewes may be carriers for several years
- Venereal transmission from infected rams
- Some immunity develops after infection, protecting ewes from subsequent disease
- Vaccination:
- Live attenuated vaccines prior to breeding or inactivated vaccines during pregnancy
- Vaccines prevent infection but will not clear infection from persistently-infected animals
- Vaccination of ewe lambs prior to breeding
- Treatment: long-acting oxytetracyclines during an outbreak to protect in-contact pregnant ewes
- Control: isolate aborted ewes; destroy placentas, thorough cleaning
- Also abortion in cattle, goats and pigs
- Serious infection in pregnant women