Notifiable Diseases Flashcards
Anthrax
agent species affected effects CS (3) Transmission
Bacillus anthracis
Mammals: zoonotic
Morbidity – low – only one or two not whole herd
Mortality - 100%
CS:
- sudden unexplained death
- pyrexia
- dysentry
Transmission: resistant spores (60yrs) through disturbance of soil
Anthrax
- Dx
- Tx (2)
- PM (2)
- control (4)
Dx:
on blood smear (stab sample from ear vein) [gram positive – blue] - polychrome methylene blue stain
Tx:
- crystalline penicillin
- Vaccination
PM
- intensely haemorrhagic carcase
- enlarged spleen
Control
- affected carcase incinerated
- contact area cleansed and disinfected
- contacts moved (treated or vaccinated)
- imports of meat & bone meal controlled
Enzootic Bovine Leukosis
- agent
- species affected
- CS (2)
- Transmission (2)
- Control
- Surveillance (4)
retrovirus
Species affected - cattle
CS:
- multicentric lymphosarcoma in cattle over 4 y.o.
- enlarged LN
Transmission:
- in lymphocytes :- lactogenic, periparturient, iatrogenic (needles,rectal gloves)
- biting flies
Control:
eradicated since 1996 in GB due to compensation and slaughter
Surveillance:
- brucella milk & blood samples screened
- all tumours (except papillomata & haemangiomata) tested (PCR for proviral DNA)
- sporadic lymphosarcoma cases investigated
- imported cattle tested (non-EU countries)
Warble Fly
- agents (2)
- species affected
- CS
- transmission
- life cycle
- pathogenesis
- Hypoderma bovis
- Hypoderma lineatum
- Species affected - cattle
CS:
- warbles’ (swellings on back)
- holes in hide
- ‘gadding” (in extreme case: posterior paralysis, anaphylactic shock)
- Transmission - flies that lay eggs
- Life Cycle - egg > larva > pupa > fly
- Pathogenesis:
Lay eggs on legs, larvae travel through spinal canal onto back, through skin and come out through breathing hole and pupate and they drop to the ground.
Warble Fly
- eradication (2)
- surveillance (4)
eradicated from GB 1990: compulsory autumn treatment (OP, Avermectin)
Surveillance:
- visual at markets & abattoirs
- serological screening of brucella bloods
- imports must be treated/tested (24hrs)
- larvae in cattle, sheep, horses (deer) screened
Bovine Brucellosis
- agent
- species affetced
- CS (4)
- Transmission (3)
Brucella abortus
Species affected:
- cattle
- zoonosis - undulant fever in people (flu like condition)
CS:
- late abortion (last 1/3 pregnancy)
- retained placenta
- carriers
- ‘abortion storms’
Transmission:
- uterine discharges
- milk, semen
- via skin, conjunctiva, ingestion, at service
Bovine Brucellosis
- bacterial survival (4)
- eradication
- Surveillance (2)
- Reactors (2)
- Controls (2)
Bacteria survive:
- slurry 8 months
- faeces 4 months
- urine 4 days
- damp soil 27days [Vectors]
1960s &1970s (Vaccination programme, then surveillance by national blood testing until 2007): 1990 UK officially free
Surveillance:
- abortions tested
- bulk milk tested quarterly (ELISA)
Reactors :
- valued and slaughtered
- farm movement restrictions
Controls:
- dealers
- imports
BSE
- agent
- CS (4)
- Transmission (2)
- FActs (3)
unknown (prion/subvirus)
CS:
- apprehension
- hypersensitivity
- ataxia
- death
Transmission :
- ruminant derived meat & bonemeal
- maternal transmittion
- Incubation period - 4-6 yrs
- Morbidity < 3%
- Mortality - 100%
BSE
- Diagnosis
- Control (6)
Diagnosis
-post mortem confirmation only: histopathology (Western blotting; immunocytochemistry; scrapie associated fibrils or SAFs)
Control
- slaughter & compensation
- no animal protein in animal feedstuffs
- no sale of milk from suspects
- SRM controls in abattoirs
- Over Thirty Month Scheme (OTMS)
- Old Cow Disposal Scheme (OCDS) ended‘08
Bovine Tuberculosis
- agent
- species affected
- Transmission (3)
- Bacterial Survival (3)
Mycobacterium bovis
Species affected - cattle, mammals, zoonosis
CS: variable: +/- cough and wasting, often absent
Transmission:
- inhalation/aerosol
- ingestion including milk
- close contact
Bacterial survival
- 11 months in warm, dark, moist conditions
- 18 days water
- 6 weeks faeces
TB
- incubation
- susceptibility
- Dx (3)
- Confirmation (2)
- Incubation period – < 60 days for immune response
- all age groups susceptible
• Diagnosis:
- single intradermal comparative cervical skin test (SICCT)
- gamma interferon blood test (infected herds)
- routine meat inspection
•Confirmation
- histopathology (not confirmatory)
- culture (8-14 weeks)
TB
- Eradication programmes in different countries
- controls (4)
eradication programmes:
• England - The Strategy for achieving Officially Bovine Tuberculosis Free status for England by 2038
• Wales - Bovine TB Eradication Programme – Annual testing of all cattle; Badger Vaccination Programme in N Pembrokeshire, July 2012. Enhanced biosecurity.
• Scotland - OTF since 2009
Controls: Passive Surveillance (Lesions at slaughter) Active Surveillance (Reactor at TB test)
• national tuberculin skin testing based on risk
- annual testing of all animals over 6 weeks of age in high risk herds and high risk areas (all of Wales; England, see map)
or
- 4-yearly testing of breeding stock in low risk areas (eg Scotland OTF since 2009)
TB Scotland
- Testing Rules (2)
- movement controls (2)
- Herds meeting criteria, “low risk”, exempt from routine TB testing (default testing interval remains 48 months for non-exempt herds)
- Approximately 35% of Scottish cattle herds exempt
Movement controls:
- pre and post movement tests if moving from high incidence herds/high incidence areas (animals >42 days old isolated, tested 60 days pre- and 60-120 days post- movement at farmer’s expense)
- post import tests eg Ireland
What animals do we test?
- Adult breeding portion of herd (cows which have calved and breeding bulls over 1 year old) as these remain in herd and
- Young stock intended for breeding, whether home bred or purchased (except calves under 6 weeks old)
Gamma Test
- one off blood test
- Gamma test designed to pick up infection earlier in disease process. Skin test is standard surveillance.
- Can only use gamma if confirmed problem.
The TB skin test:
Single intradermal comparative cervical test (SICCT)
Day 1 (13) DAy 2 (5)
Day 1:
- Apply surgical spirit to swab
- Place swab in holster
- Restrain animal
- Check identity
- Clip avian site - control
- Clip bovine site below
- Measure avian site at upper clip mark
- Measure bovine site at lower clip mark
- Record measurements
- Inject avian tuberculin into upper clip mark intradermal
- Palpate avian injection site for intradermal nodule
- Inject bovine tuberculin intradermally into lower clip mark
- Palpate bovine injection site for intradermal nodule
Day 2:
- restrain animal
- Check identity
- Measure Avian site – palpate for presence of reaction (circumscribed/oedematous)
- Measure Bovine Site - palpate for presence of reaction (circumscribed/oedematous)
- Record measurements - refer to TB64
OFT (officially TB free)
• OTFS = OTF Suspended: 1 piece of evidence of disease:
– Suspect Slaughterhouse case- TB lesions
– Reactors
• OTFW= OTF Withdrawn: 2 pieces of evidence of disease:
– Slaughterhouse case which is culture positive
– Reactors which are visibly lesioned +/or culture positive
– ‘Unconfirmed’ disease with additional risk factor
Loss of Herd OTF status = Whole herd movement restrictions apply
Visible Lesions/Culture positive (OTFW) consequences (12)
– herd movement restrictions, isolate, value and slaughter reactors
– post mortem examination and culture of samples (8-14 weeks)
– epidemiological enquiry
– Cleansing and disinfection (C&D)
– gamma interferon blood test
– Slaughter any reactors to blood test
– Retest the herd Check test all untested animals i.e animals not eligible at original test
– 60 day short interval testing (SIT) of all animals
– 2 clear skin tests - Removal of herd restrictions
– trace and test animals moved on and off
– test contiguous herds
– improve biosecurity (including wildlife)
Wildlife
- what
- infection
- excretion
- transmission
badgers:
- primary infection in pulmonary system and associated lymph node
- excretion of bacilli in sputum, urine, faeces and pus
- transmission route = aerosol. Secondary route = biting?
