Term
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Definition
-obligate pathogens (in preferred natural host) - wild animal reservoir
-shed in uterine discharges, aborted material, milk, semen, faeces (depending on site of inf.)
-poor environmental survivor - killed in hours in unprotected sunlight |
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Term
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Definition
-mucous membranes - usually ingestion
-via unbroken skin - can penetrate
-venereally
-to calf in utero / via milk |
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Term
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Definition
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Term
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Definition
-erythritol is a sugar esp. in the repro tract, esp in older animals, and this stimulate growth of Brucella
-hence has predilication for repro tract and more in older animals
-survives in polymononuclearcytes and macrophages (i.e. IC) - persists in macro. and so chronic inf. which is difficult to tx |
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Term
| Brucella - sequence of events |
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Definition
entry via MM --> lymphatics / local LNs --> blood --> various blody sites --> inflamation
At placenta --> placentitis, foetal inf. and abortion |
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Term
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Definition
IgM and IgG
CMI-R
so cleared from genital tract
...but persists IC in PMNs and phagocytes and udder |
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Term
| Brucella - carrier animals |
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Definition
-abort once
-less severe inf. at subsequent pregnancies due to CMI-R
-excrete in udder and uterine discharges and so infect others |
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Term
| Brucella - calves born to carriers (inf. in utero or via milk) |
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Definition
-as prepubescent they are rel. R (less erythritol than adults) - develop good im. resp and most clear inf. and remain R
...but ~2% retain latent inf - source of infection for others and have inf. carriers themselves |
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Term
| Brucella - why a problem? |
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Definition
-zoonotic and notifiable
-common in other parts of the world incl. Ireland and EU
-used to be major problem in UK - dec. now due to pasteruisation and eradication programme
-great economic losses - abortions, decr. milk yield, long term udder damage (welfare!) and milk loss, arthritis/bursitis
-easily transmitted to humans - get flu-like illness (aches and fever) (undulant fever) and recurrence in bones and heart (fatal) |
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Term
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Definition
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Term
| Brucella abortus - main dz. |
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Definition
| -abortion storms
-placentitis, masitis, orchitis |
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Term
| Brucella abortus - eradication scheme |
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Definition
-identify inf. herds and inf. indv.
-cull infected indv (get 75% market value compensation)
-herd restrictions - retested at 8 and 12mnths - in no +ve then restrictions lifted - if any +ve then culled, along w. dangerous contacts and herd tested every 2 months until cleared |
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Term
| Brucella abortus - regular testing programme |
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Definition
-dairy herds tested monthly (gen. bulk tank)
-beef cattle every 2 years
-test imported cattle
-test abortions |
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Term
| Brucella abortus - identifying inf. herds / tests |
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Definition
Milk Ring Test - a field test (quick, easy reliable)
-sample of milk mixed a. B abortus nd incubated
-look for agglutination Abs in milk
+ve in top cream layer is darker or same colour as milk column
-alternatively can use ELISA on bulk milk |
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Term
| Bruella - identifying infected individuals / tests |
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Definition
-bact. culture
-direct microscopy - use immunofluorescence or modified ZN / Machiavello stain
-PCR is more sensitive
-guinea pig innoculation
-serology - slide agglutination / ELISA / serum agglutination test (SAT) / complement fixation test |
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Term
| Bruella - identifying infected individuals - stains |
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Definition
modified Zielh-Neeson / Machiavello stain
-Brucella abortus is weakly acid fast so takes us primary red stain
-red stain not washed out by blue counterstain
-results in red IC bact. on blue background |
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Term
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Definition
-NOT in uk - focusing on being Brucella-free w. monitoring (and atm cost would not be economical)
-strain 19 was used in original erradication programme
-live attenuated
-huge doses needed and so caused abortion if pregnant and not used in male calves and many infertile
-female calves vacc at 2-5mnths old
-adults develop persistent antibodies to vacc / bact
NB: also RB51 licensed in USA which creares Abs which do NOT interfere w. serological tests |
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