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Lymphoreticular and haematopoeitic > LHS Infectious disease 2: FIP and FIA > Flashcards

LHS Infectious disease 2: FIP and FIA Flashcards

1
Q

Outline FIP

A
  • fatal dz
  • domestic and non-domestics
  • feline coronavirus (infection common, clinical dz uncommon)
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2
Q

What was feline coronavirus previously classified as?

A
  • feline enteric coronavirus (FECV)
  • feline infectious peritonitis virus (FIPV)
  • now thought to be biotypes of same virus
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3
Q

What type of virus is FIP?

A
  • enveloped, ssRNA
  • large, pleiomorphic
  • mutates
  • 2 types: 1 wholly feline, 2 - arises by recombination with canine coronavirus
  • 70-90% field isolates type 1, 10-30% type 2
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4
Q

Where does FIP (coronavirus) live/replicate/ etc?

A
  • replicates: cytoplasm, newly synthesised virions acquire membranes from ER and golgi, released by cell lysis or vesicle fusion with plasma membrane
  • relatively unstable outside host: inactivated at room temp in 24 h at 56 degrees for 1h, may live up to 7 wks in environment if protected (heat, light, chemicals)
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5
Q

Describe FECV

A
  • present in large % helahty cats
  • oronasal transmission
  • virus replicates in enterocytes
  • CS mild/inapparent: V, D, URT signs
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6
Q

Describe FIPV

A
  • FCoV mutation (‘internal mutation theory’ questioned by recent work showing identical nucleotide sequences of enteric and non-enteric FCoV in cat that died of FIP)
  • infects macrophages –> systemc infection
  • FIP = clinical dz syndrome from ineffective I.R.
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7
Q

Outcomes of FCoV infection

A
  • transient infection: 60-70%
  • PI: 10-15%
  • FIP 5-10%
  • resistance to FCoV infection 2-5%
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8
Q

What type of dz is FIP?

A

immune complex dz

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9
Q

What is FIP characterised by?

A
  • vasculitis
  • complement activation
  • excessive cytokine production
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10
Q

Pathophysiology - FIP

A

Viral Ag + anti-viral Ab + coplement –> complement fixation –> release of vasoactive amines –> endothelial cell retraction –> increased vascular permeability (protein rich exudate, neutrophils produce lysosomal enzymes and vessel wall necrosis)

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11
Q

How does the strength of the FIP cell-mediated I.R. affect outcome?

A
  • strong response –> protection
  • partial response –> non-effusive dz
  • poor response –> effusive dz
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12
Q

What are the CS of FIP the consequence of?

A

vasculitis and secondary organ damage

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13
Q

Incubation period - FIP

A

weeks to months (onset of CS sudden or insidious)

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14
Q

CS - early signs

A
  • generally non-specific
  • pyrexia
  • inappetance/ anorexia, wt loss
  • diarrhoea
  • listless, dehydration
  • icterus
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15
Q

T/F: in FIP, some cats may show a mixed form

A

True (mixed of effusive and non-effusive)

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16
Q

Describe the effusive form of FIP

A
  • 60-75% caes
  • abdominal effusion –> ascites
  • pleural effusion –> dyspnoea
  • pericardial effusion (less common)
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17
Q

Describe the dry form of FIP

A
  • dry or granulomatous form

- predisposition for: eye, brain, CNS, kidney, liver, localised regions of intestine

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18
Q

Dx - FIP

A
  • often difficult ante-mortem (especially dry gorm)
  • hx and CS
  • PE (always include ocular + fundic exam, look for uveitis and chorioretinitis)
  • lab / imaging findings
  • alorithms may help
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19
Q

Describe CBC for FIP

A
  • lymphopaenia
  • neutrophilia with mild left shift
  • mild non-rgenerative anaemia
  • may also be normal
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20
Q

Describe biochem for FIP

A
  • hyperglobulinaemia (by serum electrophoresis, polyclonal increse in gamma globulins, increased APPs)
  • hyperbilirubinaemia
  • usually NOT azotaemic
  • may also be normal
21
Q

Describe fluid analysis in FIP

A
  • clear, straw-yellow
  • high protein count (may clot in tube)
  • viscous, may become frothy whne shaken
  • variable cellularity (
22
Q

How is FIP coronavirus titre determined?

A
  • IFA most commonly: for anti-FCoV Ab, use FIP virus-infected feline cell lines as substrate, ELISA available
  • IFA and ELISA tests don’t distinguish cats infected with FCoV or FIPV: positive titre indicates prior exposure to FCoV, not necessarily the presence of FIP, rare negative titres in FIP, predictive significance of high titres
23
Q

What other diagnostic tests can you use for FIP?

A
  • CSF: dry tap or increased protein and cells
  • OTHER TESTS TO DEMONSTRATE FCoV: direct FA adn IHC (tissue sections), RT-PCR detects viral genomic RNA (positive in healthy cat), new RT-PCR detects sub-genomic mRNA therefore replicating virus in circulating
24
Q

What is alpha1-acid glycoprotein?

A
  • an APP produced by liver in response to inflammatory stimuli
  • increased serum not specific for FIP but can be useful in combination with other clinical findings
  • if 1500 increased index of suspicion
25
Q

Histopathology of FIP

A
  • light plaques on serosal surfaces, adhesions of omentum and mesentery
  • liver, spleen, kidney, omentum, mesenteric LN, most commonly affected
26
Q

Tx / prognosis - FIP

A
  • grave prognosis: no cure for dz in large majority of cases, tx palliative
  • remission/ cure reported - questionable
  • options:
  • supportive/ palliative care: ABs, SQ fluids, nutrition, rest, thoracocentesis
  • immune-modulators
  • GCs +/- chlorambucil
  • aspirin? (care - cats)
  • oral polyprenyl immunostimulant
27
Q

Outline vaccination against FIP

A
  • strong cell-mediated immune response without strong Ab response
  • Primucell: T-sensitive mutant of serotype 1 FCoV, IN administration, local I.R., induced low IgG titres, efficacy controversial, but safe, no ADR
28
Q

Key points with FIP

A
  • difficult to diagnose
  • only way to confirm is histopath
  • non-effusive dz hardest to dx
  • cannot predict which cats will develop dz
29
Q

What is the reclassification of feline infectious anaemia (FIA)?

A

Haemotropic mycoplasma (haemoplasmas) - small epicellular parasites, no cell wall, TC-sensitive

30
Q

What can cause FIA?

A
  • Mycoplasma haemofelis: most pathogenic form (–> anaemia)
  • Candidatus Mycoplasma haemominutum: less pathogenic
  • Canididatus Mycoplasma turicensis: documented in swiss cat with haemolytic anaemia, SPF cats mild to severe anaemia
31
Q

Outline pathogenesis of FIA

A
  • Mycoplasma attach to RBCs –> I-M destruction
  • concurrent dz, immunosuppression –> enhanced dz
  • if recover from infection –> chronic infection for variable time (reactivation and recurrence possible)
32
Q

Describe Mycoplasma haemofelis

A
  • associated with anaemia
  • pleiomorphic: rods, rings or spherical
  • gram negative
33
Q

Possible routes of transmission of haemotropic mycoplasmas

A
  • fleas
  • blood transfusion
  • female cats to neonates (in utero, nursing)
  • fighting
  • oral
  • experimenting (IP, IV and PO infected blood, urine and saliva not thought to be infective)
34
Q

Describe infection with Mycoplasma haemofelis

A
  • dz more common in young, entire males
  • often infection ‘latent’
  • stress/ concurrent illness –> acute disease
  • recovered cat may have relapse with stress
35
Q

Outline PCV changes with FIP

A
  • may cases: rapid decrease in PCV, organisms in blood (go to spleen)
  • PCV rises as organisms disappear
  • some cats (PCV continues to decrease after parasitaemic episode, result of RBC destruction)
36
Q

Outline anemia in FIA cats

A
  • direct damage to RBC

- I-M injury: Coombs’ test may be positive, extravascular haemolysis by macrophages in liver, spleen, lungs and BM

37
Q

CS - M.haemofelis

acute and chronic signs

A 
ACUTE INFECTION:
- lethargy
- inappetance/ anorexia
- fever
- anaemia (39-41 degrees)
- splenomegaly
- icterus
CHRONIC INFECTION:
- normal to subnormal temperature
- weakness
- depression
- wt loss/ emaciation
- icterus and splenomegaly less likely
38
Q

Outline CBC for FIA

A
  • REGENERATIVE ANAEMIA: varies in severity (PCV 15-18%), reticulocytosis, regenerative morphology
  • If acute onset anaemia, may be pre-regenerative
  • Eryhthrophagocytosis and autoagglutination may be present
  • leukocyte count variable: leucocytosis with monocytosis in acute forms, normal counts in chronic forms, leucopaenia in moribund
39
Q

How can M.haemofelis be detected?

A
  • fresh blood smear: EDTA may displace organism
  • organisms only noted in about 50% acute dz cases (fluctuating numbers): repeat daily for 5-10d
  • diferentiate from Howell-Jolly bodies, basophilic stippling, stain precipittes
  • apparent absence doesn’t r/o dx
  • acridine orange stain, IFA
  • PCR: sensitive, amplification of DNA from organism in vitro, can distinguish b/w M. haemofelis and Candidatus M haemomintum
  • evaluate for other dz
40
Q

Tx - FIA

A
  • DOXYCYCLINE: 5-10mg/kg, orally BID for 14-21d
  • potential AEs: GIT, abdominal discomfort, vomiting, inappetence/ anorexia, oesophagitis, oesophgeal stricture formation
  • POSS ALTERNATIVE = enrofloxacin 5-10mg/kd orally SID for 2wks but acute irreversible retinal degeneration, blindness. Marbofloxacin
  • FLEA CONTROL: especially FeLV or FIV positive cats, likely to relapse
  • SUPPORTIVE CARE: blood transfusion if necessary (compatible blood type essential), immunosuppressive therapy (prednisolone) to inhibit erythrophagocytosis, gradually reduce dose
41
Q

Px - FIA

A
  • no tx: approxiamtely 1/3 with uncomplicated acute dz die
  • regeneration –> destruction + immune response to organism –> recovery
  • recovery phase: last parasitaemia to PCV stabilisation > 1 month
  • carrier state
42
Q

Distinguish enzootic and epizootic - FIP

A
  • ENZOOTIC (commonest): sporadic, infrequent, unpredictable losses
  • EPIZOOTIC: high losses (50%, esp juveniles), may last 6-12 mo then reverts to enzootic, may be d/t intro of new sttrain
43
Q

Control - FIP

A
  • ↓ stress
  • ↓ faecal contam.
  • small groups by age and Ab status
  • FeCoV seronegative household
  • test incoming cats
  • prepare kitten room
  • barrier nurse
  • wean/isolate kittens early (5-6wks) if seropositive queen
  • test for anti-FCoV Ab after 10 wks
44
Q

Actions - cat with FIP

A
  • don’t introduce new kitten

- coronavirus can persist up to 7 wks in environement (wait 2 mo after removal)

45
Q

Effect of Candidatus mycoplasma haemominutum

A
  • common isolate of healthy cats
  • experimental infection (minimal CS of acute dz and minimal haematological changes)
  • experimental co-infection with FeLV causes more severe anaemia
  • chronic infxn (may promote neoplastic transformation of haemopoietic cells in cats with FeLV)
46
Q

Effect of splenectomy in FIA

A

fewer parasites (Candidatus Mycoplasma haemomintum) removed but splenectomy nt as significant in cats as other spp

47
Q

Ddx - FIA

A
  • FelV-induce HA
  • IMHA of other causes
  • tx prior to results is for FIA and IMHA
48
Q

Serum biochemistry - FIA

A
  • increased ALT and AST
  • hyperbilirubinaemia
  • increased [TP]
  • hypoglycaemia (moribund cats)
49
Q

Describe FIA carrier state

A
  • clinically normal
  • recovered from acute dz (chronically infected, possibly for life)
  • normal PCV/ mild regen. anaemia
  • organisms: low #s or absent
  • opportunistic? may observe acute dz with stress

Lymphoreticular and haematopoeitic (21 decks)

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