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#REDIRECT[[:Category:Chlamydophila species]]
 
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<br>
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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 - Pathology#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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*[[Respiratory Bacterial Infections - Pathology#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-Neelsen) 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 embryonated 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 - Pathology#In Sheep|arthritis in sheep]] and [[Joints Inflammatory - Pathology#In Cattle|arthritis in cattle]]
 
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