Term
| Chlymadiales and rickettsiales - similarities |
|
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 |
|
|
Term
|
Definition
-Chlamydia spp.
-Chlamydophilia psittaci (avian chlamydiosis / grannies dz)
-Chylamydiolphilia abortus (EAE)
-Chylamydiophila felis (feline chlamydiosis) |
|
|
Term
| Chlamydiales - intracellular survival |
|
Definition
| -live in endosome - modify the compartment - insert proteins into endosome membrane so doesn't become fully acidified |
|
|
Term
| Chlamydiales - extracellular transmission |
|
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 |
|
|
Term
| Chlamydiales - life cycle |
|
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 |
|
|
Term
| Chlamydiales - dz. trends |
|
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 |
|
|
Term
| Chlamydophilia psittaci - dz |
|
Definition
Avian chlamydiosis
-resp and intestinal inf. w. high mortality |
|
|
Term
| Chlamydophilia psittaci - source |
|
Definition
-EB shed in faeces
-subclinical carriers shed when stresed |
|
|
Term
| Chlamydophilia psittaci - sequence of events |
|
Definition
| inhalation of EB --> acute systemic dz --> ocular / nasal discharges and green bloody diarrhoea --> high mortality |
|
|
Term
| Chlamydophilia psittaci - zoonoses |
|
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. |
|
|
Term
| Chlamydophilia abortus - main dz |
|
Definition
| Enzootic Abortion of Ewes (EAE) - cause of ~90% ovine abortion in UK |
|
|
Term
| Chlamydophilia abortus - source |
|
Definition
| ingestion of EBs in placentas / uterine discharge / environment |
|
|
Term
| Chlamydophilia abortus - infection late pregnancy |
|
Definition
no abortion
BUT may abort next pregnancy or ewelambs may be subclinically infected and then abort |
|
|
Term
| Chlamydophilia abortus - infection early pregnancy |
|
Definition
abortion in late pregnacy
or premature / weak lambs which if ewelambs may be subclinically infected and then abort |
|
|
Term
| Chlamydophilia felis - disease |
|
Definition
Feline chlamydiosis - conjunctivitis, rhinitis
-endemic - low mortality and usually self limiting
-but persists subclinically so get relapses |
|
|
Term
| Chlamydial infection - tx |
|
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) |
|
|
Term
| Chlamydial infection - prevention |
|
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 |
|
|
Term
|
Definition
-Ehrlichiaceae
-Rickettsiaeae |
|
|
Term
| Rickettsiales - intracellular survival |
|
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 |
|
|
Term
|
Definition
mucous membrane epithelial cells
+/- macrophages if penetrate |
|
|
Term
| Rickettsiales - cell type |
|
Definition
Ehrlichia - RBC and WBC (multiple in vaculoles)
Rickettsia - capillary endothelial cells, mutliple in cytoplasm |
|
|
Term
| Rickettsiales - transmission |
|
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 |
|
|
Term
|
Definition
-very similar to chlamydials
-plus blood transfusion if necessary |
|
|
Term
| Rickettsiales - prevention |
|
Definition
-very similar to Chlamydiales
-plus vector control |
|
|
Term
| Chlamydial and rickettsial infection - dx |
|
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) |
|
|
Term
| Ehrlichia phagocytophila - dz |
|
Definition
| tick borne fever - initially fever then chronic immunosuppression |
|
|
Term
| Ehrlichia phagocytophila - spp affected |
|
Definition
| ruminants - esp. in tick-infected areas affecting lambs |
|
|
Term
| Ehrlichia phagocytophila - sequence of events |
|
Definition
infects granulocytes --> fluctuating fever for a few days
persistence of organism --> relapses --> chronic immunosuppression --> susceptible to other serious infections |
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