|
|
| (9 intermediate revisions by 4 users not shown) |
| Line 1: |
Line 1: |
| − | <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>
| |
| − | | |
| − | | |
| − | ''Chlamydophila psittaci'' involved in [[Nasal cavity - inflammatory#In Cats|feline rhinotracheitis]] together with [[Herpesviridae|herpes virus 1]] C.psittaci more frequently infects the conjunctival epithelium -> chronic conjunctivitis, see [[Bacterial infections#Feline Chlamydiosis|feline chlamydiosis]]
| |
| − | | |
| − | *May cause [[Joints - inflammatory#In Sheep|arthritis in sheep]] and [[Joints - inflammatory#In Cattle|arthritis in cattle]]
| |
| − | | |
| − | ===Overview===
| |
| − | | |
| − | *Host adapted and non-host adapted species varying in virulence for different hosts
| |
| − | *Species cause specific diseases in particular hosts
| |
| − | *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
| |
| − | *Human infections usualy acquired from infected birds, causing psittacosis or ornthosis, causing respiratory infections
| |
| − | | |
| − | | |
| − | ===Characteristics===
| |
| − | | |
| − | *Obligate intracellular bacteria
| |
| − | *Gram negative bacteria with outer membrane, LPS, ribosomes, DNA and RNA
| |
| − | *Peptidoglycan cell wall resistant to lysozyme
| |
| − | *Only grow in presence of living eukaryotic cells
| |
| − | *Unable to synthesis ATP therefore require intermediates from host cells
| |
| − | *Not stained by Gram stain
| |
| − | *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
| |
| − | **Retiuculate body: larger, metabolically active, osmotically fragile
| |
| − | *Elementary body survives in the environment for several days
| |
| − | | |
| − | | |
| − | ===Pathogenesis and pathogenicity===
| |
| − | | |
| − | *Elementary body enters host epithelial cells by receptor-mediated endocytosis
| |
| − | *Transformation into larger reticulate body within endosome; known as an inclusion
| |
| − | *Reticulate body divides by binary fission to form many new chlamydia cells
| |
| − | *Reticulate bodies mature and condense to form elementary bodies
| |
| − | *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 such as presence of interferon gamma
| |
| − | *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
| |
| − | *Prolonged faecal shedding of organisms
| |
| − | *Clinical infections occur in non-natural host species
| |
| − | *CLinical signs depend on route of infection and degree of exposure
| |
| − | | |
| − | | |
| − | ===''Chlamydophila psittaci''===
| |
| − | | |
| − | *Causes notifiable psittacosis in birds
| |
| − | | |
| − | | |
| − | ===''Chlamydophila abortus''===
| |
| − | | |
| − | *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
| |
| − | | |
| − | | |
| − | ===''Chlamydophila felis''===
| |
| − | | |
| − | *Host adapted species in cats
| |
| − | *Feline conjunctivitis, rhinitis and rarely interstitial pneumonia
| |
| − | *Epidemiology
| |
| − | **Up to 10% cats infected
| |
| − | **Infection via contact with conjunctival or nasal secretions
| |
| − | **Infection may persist with prolonged shedding and clinical relapses
| |
| − | **Stress of parturition and lactation may cause shedding of organisms leading to transmission to offspring
| |
| − | *Clinical signs:
| |
| − | **Incubation period 5 days
| |
| − | **Conjunctival congestion, clear ocular discharge, blepharospasm
| |
| − | **May have sneezing and nasal discharge
| |
| − | **Resolves within a few weeks, or causes persistent infection
| |
| − | *Diagnosis:
| |
| − | **Intracytoplasmic inclusions in stained conjunctival smears
| |
| − | **Antigen detection in ocular/nasal secretions - ELISA, PCR, Kosters, fluorescent antibody test
| |
| − | *Modified live vaccines reduce clinical signs but do not prevent infection or shedding
| |
| − | | |
| − | | |
| − | ===''Chlamydophila pecorum''===
| |
| − | | |
| − | *Neurological disease
| |
| − | *Common intestinal infection of cattle
| |
| − | *Sporadic bovine encephalomyelitis:
| |
| − | **Usually in cattle under 3 years
| |
| − | **Fever, incoordination, depression, excessive salivation, diarrhoea
| |
| − | **Recumbency and opisthotonos before death
| |
| − | **Up to 50% mortality
| |
| − | **Vacular damage in brain
| |
| − | **Serofibrinious peritonitis
| |
| − | | |
| − | ===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
| |