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| − | <big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
| + | #REDIRECT[[:Category:Chlamydophila species]] |
| − | <big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
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| − | ===Overview===
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| − | *Host adapted and non-host adapted species varying in virulence for different hosts
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| − | *Species cause specific diseases in particular hosts
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| − | *Repsiratory, enteric, pleural and reproductive diseases in animals and humans
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| − | *Conjunctivitis, arthritis, abortion, urethritis, enteritis, pneumonia, encephalomyelitis
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| − | *Manifestation varies from subclinical to severe systemic infections
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| − | *Intestinal infections often subclinical and persistent
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| − | *Human infections usualy acquired from infected birds, causing psittacosis or ornithosis, causing respiratory infections
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| − | ===Characteristics===
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| − | *Obligate intracellular bacteria
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| − | *Gram negative bacteria with outer membrane, LPS, ribosomes, DNA and RNA
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| − | *Peptidoglycan cell wall resistant to lysozyme
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| − | *Only grow in presence of living eukaryotic cells
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| − | *Unable to synthesis ATP therefore require intermediates from host cells
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| − | *Not stained by Gram stain
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| − | *Two morphological forms
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| − | **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
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| − | **Retiuculate body: larger, metabolically active, osmotically fragile
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| − | *Elementary body survives in the environment for several days
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| − | ===Pathogenesis and pathogenicity===
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| − | *Elementary body enters host epithelial cells by receptor-mediated endocytosis
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| − | *Transformation into larger reticulate body within endosome; known as an inclusion
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| − | *Reticulate body divides by binary fission to form many new chlamydia cells
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| − | *Reticulate bodies mature and condense to form elementary bodies
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| − | *Elementary bodies released from dying host cells after about 72 hours to infect other cells
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| − | *Persistent infections can occur if replication delayed by environmental conditions such as presence of interferon gamma
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| − | *Many infections subclinical due to intracellular existence of ''chlamydia'' preventing inflammatory reactions
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| − | *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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| − | *Prolonged faecal shedding of organisms
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| − | *Clinical infections occur in non-natural host species
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| − | *CLinical signs depend on route of infection and degree of exposure
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| − | ===''Chlamydophila psittaci''===
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| − | *Causes notifiable psittacosis in birds
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| − | *Epidemiology:
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| − | **Many wild and domestic birds susceptible
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| − | **Organisms present in respiratory secretions and faeces of infected birds
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| − | **Infection via inhalation or ingestion
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| − | **Subclinical infection common
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| − | **Intermittent shedding for prolonged periods
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| − | **Stress precipitates disease outbreaks
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| − | *Clinical signs:
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| − | **Generalised infection affecting intestinal and respiratory tracts
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| − | **Up to 10 day incubation period
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| − | **Loss of condtion, oculonasal discahrge, diarrhoea and respiratory distress depending on strain
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| − | **Hepatomegaly, airsacculitis and peritonitis
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| − | *Diagnosis: stained smears, immunohistochemistry, ELISA, PCR, isolation, antibody detection by ELISA and complement fixation
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| − | *Treatment: tetracyclines for several weeks
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| − | *Control: quaranteen imported birds and give tetracyclines; good husbandry
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| − | *Involved in [[Nasal cavity - inflammatory#In Cats|feline rhinotracheitis]] together with [[Herpesviridae|herpes virus 1]]
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| − | *Zoonotic by aerosol infection - can cause systemic disease with pneumonia, meningitis or meningoencephalitis
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| − | ===''Chlamydophila abortus''===
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| − | *Ovine enzootic abortion
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| − | *Especially in intensive systems
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| − | *Ewe lambs may acquire infection at birth and abort in their first pregnancy
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| − | *Pathogenesis:
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| − | **Infection via ingestion or inhalation causes a bacteraemia
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| − | **Bacteria localise in placenta and cause placentitis, leading to late abortion or premature weak lambs
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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
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| − | **Fertility not impaired
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| − | *Transmission:
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| − | **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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| − | **Ewes may be carriers for several years
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| − | **Venereal transmission from infected rams
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| − | **Some immunity develops after infection, protecting ewes from subsequent disease
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| − | *Vaccination:
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| − | **Live attenuated vaccines prior to breeding or inactivated vaccines during pregnancy
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| − | **Vaccines prevent infection but will not clear infection from persistently-infected animals
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| − | **Vaccination of ewe lambs prior to breeding
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| − | *Treatment: long-acting oxytetracyclines during an outbreak to protect in-contact pregnant ewes
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| − | *Control: isolate aborted ewes; destroy placentas, thorough cleaning
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| − | *Also abortion in cattle, goats and pigs
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| − | *Serious infection in pregnant women
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| − | ===''Chlamydophila felis''===
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| − | *Host adapted species in cats
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| − | *[[Bacterial infections#Feline Chlamydiosis|Feline chlamydiosis]]
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| − | *Feline conjunctivitis, rhinitis and rarely interstitial pneumonia
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| − | *Epidemiology
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| − | **Up to 10% cats infected
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| − | **Infection via contact with conjunctival or nasal secretions
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| − | **Infection may persist with prolonged shedding and clinical relapses
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| − | **Stress of parturition and lactation may cause shedding of organisms leading to transmission to offspring
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| − | *Clinical signs:
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| − | **Incubation period 5 days
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| − | **Conjunctival congestion, clear ocular discharge, blepharospasm
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| − | **May have sneezing and nasal discharge
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| − | **Resolves within a few weeks, or causes persistent infection
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| − | *Diagnosis:
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| − | **Intracytoplasmic inclusions in stained conjunctival smears
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| − | **Antigen detection in ocular/nasal secretions - ELISA, PCR, Kosters, fluorescent antibody test
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| − | *Modified live vaccines reduce clinical signs but do not prevent infection or shedding
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| − | ===''Chlamydophila pecorum''===
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| − | *Common inapparent intestinal infection of cattle
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| − | *Conjunctivitis and arthritis
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| − | *Sporadic bovine encephalomyelitis:
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| − | **Usually in cattle under 3 years
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| − | **Fever, incoordination, depression, excessive salivation, diarrhoea
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| − | **Recumbency and opisthotonos before death
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| − | **Up to 50% mortality
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| − | **Vacular damage in brain
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| − | **Serofibrinious peritonitis
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| − | **Treat with high doses tetracyclines and tylosin
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| − | ===Diagnosis===
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| − | *Direct microscopy of smears and tissues e.g. organs from aborted foetuses, liver/spleen from avian cases
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| − | *Kosters (modified Ziehl-Neelson) stain of placental smears shows small red rods
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| − | *Blue inclusions in cytoplasm of Giemsa-stained cells
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| − | *Methylene blue stain with darkfield microscopy
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| − | *Fluorescent antibody stain
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| − | *Antigen detection kits for diagnosis from swabs
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| − | *ELISA to detect ''Chlamydophila'' LPS
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| − | *Isolation in embyonated eggs and McCoy cells as well as animal tissues
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| − | *PCR to detect chlamydial DNA
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| − | *Serological tests: complement fixation, ELISA, indirect immunofluorescence
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| − | *May cause [[Joints - inflammatory#In Sheep|arthritis in sheep]] and [[Joints - inflammatory#In Cattle|arthritis in cattle]]
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