3. Diagnosis of infectious diseases, treatment of animals having infectious diseases. Flashcards
How do we diagnose infectious diseases
It is complex! Epidemiological data: vet CS, allergic reactions PM lesions Preliminary diagnosis - Ddx --> if suspicion for notifiable disease/xoonosis - test for it right away Lab exam: 1. Sampling: appropriate number, how to sample correctly and covering letter 2. Clinical observations and necropsy 3. Histological examination
How can we directly detect the agent itself?
Microscopy: organs, fluids, smear
Isolation: medium, cell culture, CAM, lab animal - good for bacteria
Detection of antigens: IF, ELISA, western/immunoblot, electrophoresis
Methods detecting nucleic acids: DNA hybridization, PCR, can detect some genes for virulence factors
What are indirect detection methods?
Detecting antibodies or immune cellular reactions
Classical: agglutination, precipitation, electropphoresis, PAGE, complement fixation
Virus serology: VNT, HAI (infl, parainfl)
Marked immunological methods: IF, ELISA
+ CELLULAR TESTS - not widely used
Cellular tests
LST - lymphocyte stimulation test (paratuberculosis)
Allergic test - tuberculin
Gamma interferon test (mycobacteria)
Sensitivity of diagnostic test
Can detect large number of positive cases
Specificity of diagnostic test
No cross reactions, when it is positive, it should not be false
Sensitivity and specificity is influenced by
- amount & antigenicity of the agent, phase of the pathogenesis
- Indirect: needs time for the immune reaction, so can’t be used in acute
phase of pathogenesis, but can be used even after clinical signs disappear - More diagnostic methods have to be used AND they have to evaluated together with the pathogenesis/Clinical
signs/PM lesions - complex final evaluation
Etiological treatment
Bacteria (own metabolism): AB treatment (appropriate medicine –prudent use!)
Hyper-immune serum: animals vaccinated many times producing high level of antibodies then the blood is taken and the serum from them is used to treat other animals with their serum – not widely used
Viruses: antiviral medicines (limited use, very expensive, have to be used in the appropriate phase of the pathogenesis)
Symptomatic treatment
Support the healing/immune system of the animals - animal welfare + eliminate predisposing factors
Treatment of which diseases are not allowed
NOTIFIABLE det burde du vite
Prevention of complications
Mainly viral diseases - can give antibiotics e.g. IBR to avoid secondary complications
Name two chronic diseases that cannot be treated or treatment is not reasonable (easier to slaugther than to treat)
Swine/Fowl typhoid - salmonella
