462
edits
Changes
Jump to navigation
Jump to search
Chlamydia and Chlamydophila species (view source)
Revision as of 10:34, 18 May 2008
, 10:34, 18 May 2008no edit summary
*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
*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
*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
*Not stained by Gram stain
*Not stained by Gram stain
*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
*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
*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
*Ovine enzootic abortion
*Ovine enzootic abortion
*Contagious ovine abortion in late pregnancy
*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
*Bacteria localise in placenta and cause placentitis, leading to late abortion or premature weak lambs
*Abortion rates may reach 30%
*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
*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
*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
*Also abortion in cattle, goats and pigs
===Diagnosis===
===Diagnosis===
*Direct microscopy of smears and tissues e.g. organs from aborted foetuses, liver/spleen from avian cases
*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
*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