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*Host adapted and non-host adapted species varying in virulence for different hosts
 
*Host adapted and non-host adapted species varying in virulence for different hosts
*Different species cause specific diseases in particular hosts
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*Species cause specific diseases in particular hosts
 
*Repsiratory, enteric, pleural and reproductive diseases in animals and humans
 
*Repsiratory, enteric, pleural and reproductive diseases in animals and humans
 +
*Conjunctivitis, arthritis, abortion, urethritis, enteritis, pneumonia, encephalomyelitis
 +
*Manifestation varies from subclinical to severe systemic infections
 
*Intestinal infections often subclinical and persistent
 
*Intestinal infections often subclinical and persistent
 +
*Human infections usualy acquired from infected birds, causing psittacosis or ornthosis, causing respiratory infections
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*Only grow in presence of living eukaryotic cells
 
*Only grow in presence of living eukaryotic cells
 
*Unable to synthesis ATP therefore require intermediates from host cells
 
*Unable to synthesis ATP therefore require intermediates from host cells
*Grow in embyonated eggs and McCoy cells as well as animal tissues
   
*Not stained by Gram stain
 
*Not stained by Gram stain
*Kosters (modified Ziehl-Neelson, small red rods) or fluorescent antibody stain required for detection
  −
*Blue inclusions in cytoplasm of Giemsa-stained cels
  −
*Antigen detection kits for diagnosis from swabs
   
*Two morphological forms
 
*Two morphological forms
 
**Elementary body, the infective extracellular form, which is small, metabolically inert and osmotically stable; surrounded by cytoplasmic membrane, outer membrane with LPS, but no peptidoglycan
 
**Elementary body, the infective extracellular form, which is small, metabolically inert and osmotically stable; surrounded by cytoplasmic membrane, outer membrane with LPS, but no peptidoglycan
 
**Retiuculate body: larger, metabolically active, osmotically fragile
 
**Retiuculate body: larger, metabolically active, osmotically fragile
 
*Elementary body survives in the environment for several days
 
*Elementary body survives in the environment for several days
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*Reticulate bodies mature and condense to form elementary bodies
 
*Reticulate bodies mature and condense to form elementary bodies
 
*Elementary bodies released from dying host cells after about 72 hours to infect other cells
 
*Elementary bodies released from dying host cells after about 72 hours to infect other cells
*Persistent infections can occur if replication delayed by environmental conditions
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*Persistent infections can occur if replication delayed by environmental conditions such as presence of interferon gamma
 
*Many infections subclinical due to intracellular existence of ''chlamydia'' preventing inflammatory reactions
 
*Many infections subclinical due to intracellular existence of ''chlamydia'' preventing inflammatory reactions
 
*Chronic infections  may fail to induce an immune response, or may repeatedly stimulate the immune system, causing a delayed hypersensitivity reaction and tissue damage
 
*Chronic infections  may fail to induce an immune response, or may repeatedly stimulate the immune system, causing a delayed hypersensitivity reaction and tissue damage
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*Ovine enzootic abortion
 
*Ovine enzootic abortion
*Contagious ovine abortion in late pregnancy
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*Especially in intensive systems
 +
*Ewe lambs may acquire infection at birth, and abort in their first pregnancy
 
*Infection via ingestion or inhalation causes a bacteraemia
 
*Infection via ingestion or inhalation causes a bacteraemia
*Bacteria localise in placenta and cause placentitis, leading to abortion
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*Bacteria localise in placenta and cause placentitis, leading to late abortion or premature weak lambs
*Abortion rates may reach 30%
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*Necrosis of cotyledons and oedema of adjacent tissue, as well as dirty pink uterine discharge
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*Aborted lambs well preserved
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*Large numbers of chlamydiae shed in placenta and uterine discharges; survive in environment for several days
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*Abortion rates may reach 30% in susceptible flock
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*Ewes infected late in pregnancy may not abort, but may abort during the next pregnancy
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*No other clinical signs in aborting ewes
 
*Fertility not impaired
 
*Fertility not impaired
 
*Survival of elementary bodies in faeces and wild birds are a source of infection from one lambing season to the next
 
*Survival of elementary bodies in faeces and wild birds are a source of infection from one lambing season to the next
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*Vaccines prevent infection but will not clear infection from persistently-infected animals
 
*Vaccines prevent infection but will not clear infection from persistently-infected animals
 
*Vaccination of ewe lambs
 
*Vaccination of ewe lambs
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*Also abortion in cattle, goats and pigs
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===Diagnosis===
 
===Diagnosis===
   −
 
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*Direct microscopy of smears and tissues e.g. organs from aborted foetuses, liver/spleen from avian cases
===Treatments===
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*Kosters (modified Ziehl-Neelson) stain of placental smears shows small red rods
 +
*Blue inclusions in cytoplasm of Giemsa-stained cells
 +
*Methylene blue stain with darkfield microscopy
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*Fluorescent antibody stain
 +
*Antigen detection kits for diagnosis from swabs
 +
*ELISA to detect ''Chlamydophila'' LPS
 +
*Isolation in embyonated eggs and McCoy cells as well as animal tissues
 +
*PCR to detect chlamydial DNA
 +
*Serological tests: complement fixation, ELISA, indirect immunofluorescence
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