Term
Chlymadiales and rickettsiales - similarities |
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Definition
-both IC survival
-have all the enzymes and machinery they need
-but unable to synthesise all precursors (missing some cofactors and so unable to make sufficient E)
-therefore totally reliant on host |
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Term
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Definition
-Chlamydia spp. -Chlamydophilia psittaci (avian chlamydiosis / grannies dz) -Chylamydiolphilia abortus (EAE) -Chylamydiophila felis (feline chlamydiosis) |
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Term
Chlamydiales - intracellular survival |
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Definition
-live in endosome - modify the compartment - insert proteins into endosome membrane so doesn't become fully acidified |
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Term
Chlamydiales - extracellular transmission |
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Definition
totally reliant on the host, can not be transmitted by traditional routes. There are distinct forms of chlamydiales Elementary body (EB) is the infectious form - it is dehydrated, w. a R wall and is metabolically inactive i.e. spore like The reticulate body (RB) is the intracellular form which is active and replicates |
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Term
Chlamydiales - life cycle |
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Definition
-EB attaches to host cell and stimulates uptake by PIE and favourable conditions -EB --> RB i.e. wall softens, rehydrates -RB undergoes binary fission and there is formation of inclusion bodies -RB reaches certain point , condenses --> EB -cell lysis and EB released |
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Term
Chlamydiales - dz. trends |
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Definition
-associated w. MM resp, GIT, conjunctival and UGT - some can cross and give rise to systemic dz (esp GIT) - arthritis, encephalomyelitis -subclinical persistence and clinical flare-ups over years |
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Term
Chlamydophilia psittaci - dz |
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Definition
Avian chlamydiosis -resp and intestinal inf. w. high mortality |
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Term
Chlamydophilia psittaci - source |
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Definition
-EB shed in faeces -subclinical carriers shed when stresed |
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Term
Chlamydophilia psittaci - sequence of events |
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Definition
inhalation of EB --> acute systemic dz --> ocular / nasal discharges and green bloody diarrhoea --> high mortality |
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Term
Chlamydophilia psittaci - zoonoses |
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Definition
psittascosis "grannies dz / parrot fever" -generally associated w. pet birds -inhalation of EB w. dried faeces, esp when cleaning cage -resp inf / pneumonia and poss systemic spread -death in 20% untreated cases (NB: generally older population associated) Can also get in association w. turkeys / pigeons. |
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Term
Chlamydophilia abortus - main dz |
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Definition
Enzootic Abortion of Ewes (EAE) - cause of ~90% ovine abortion in UK |
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Term
Chlamydophilia abortus - source |
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Definition
ingestion of EBs in placentas / uterine discharge / environment |
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Term
Chlamydophilia abortus - infection late pregnancy |
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Definition
no abortion BUT may abort next pregnancy or ewelambs may be subclinically infected and then abort |
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Term
Chlamydophilia abortus - infection early pregnancy |
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Definition
abortion in late pregnacy or premature / weak lambs which if ewelambs may be subclinically infected and then abort |
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Term
Chlamydophilia felis - disease |
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Definition
Feline chlamydiosis - conjunctivitis, rhinitis -endemic - low mortality and usually self limiting -but persists subclinically so get relapses |
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Term
Chlamydial infection - tx |
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Definition
- difficult! - need antibiotics to be clinically effective IC -antibiotics usually oxytetracyline for 2-3 weeks, NOT penicillin (affects bact. cell wall but unable to lyse it, so may push IC) |
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Term
Chlamydial infection - prevention |
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Definition
-detergents - due to high lipid content EBs are sensitive - should be rel. easy to remove from cage -vaccines are available - feline chlamydiosis vacc (but largely ineffective) -avian chlamydiosis - regulated dz (NB this does not mean notifiable!) -EAE - live attenuated vacc. used pre-breeding, or inactivated in preg -as avian chlamydiosis is regulated, imported birds muct be quarantined for 35-45 days |
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Term
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Definition
-Ehrlichiaceae -Rickettsiaeae |
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Term
Rickettsiales - intracellular survival |
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Definition
-entry via PIE -Ehrlichia live in endosome -Rickettsia escape from endosome - have lipases which degrade the endo. wall an so escape and survive in cytoplasm |
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Term
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Definition
mucous membrane epithelial cells +/- macrophages if penetrate |
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Term
Rickettsiales - cell type |
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Definition
Ehrlichia - RBC and WBC (multiple in vaculoles) Rickettsia - capillary endothelial cells, mutliple in cytoplasm |
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Term
Rickettsiales - transmission |
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Definition
totally reliant on the host, can not be transmitted by traditional routes. -transmitted by blood-sucking arthropod vectors Can be mechanical or biological vectors |
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Term
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Definition
-very similar to chlamydials -plus blood transfusion if necessary |
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Term
Rickettsiales - prevention |
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Definition
-very similar to Chlamydiales -plus vector control |
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Term
Chlamydial and rickettsial infection - dx |
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Definition
-ID bact in lesion smear - Giemsa stain / IF show inclusion bodies w. RBs -PCR -serology on paired sera from several birds - ELISA, indirect IF -isolation - tissue cultures / embryonated eggs (won't grow on normal agar) |
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Term
Ehrlichia phagocytophila - dz |
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Definition
tick borne fever - initially fever then chronic immunosuppression |
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Term
Ehrlichia phagocytophila - spp affected |
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Definition
ruminants - esp. in tick-infected areas affecting lambs |
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Term
Ehrlichia phagocytophila - sequence of events |
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Definition
infects granulocytes --> fluctuating fever for a few days persistence of organism --> relapses --> chronic immunosuppression --> susceptible to other serious infections |
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