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Feline Infectious Peritonitis (view source)
Revision as of 15:24, 18 October 2008
, 15:24, 18 October 2008no edit summary
*FECoV may cause mild respiratory symptoms and diarrhoea but is often asymptomatic
*FECoV may cause mild respiratory symptoms and diarrhoea but is often asymptomatic
*Weeks, months or years may intervene between localized primary FECoV infection and FIP development
*Weeks, months or years may intervene between localized primary FECoV infection and FIP development
*FECoV replicates in the gut, but FIP spreads systemically in the circulation
*FIP gains ability to replicate in monocytes and macrophages
*FIP gains ability to replicate in monocytes and macrophages
*Almost invariably '''fatal'''
*Almost invariably '''fatal'''
*Failure of the immune system to clear antibody-antigen complexes leads to '''immune-mediated disease'''
*Failure of the immune system to clear antibody-antigen complexes leads to '''immune-mediated disease'''
**Deposited complexes cause '''inflammation''' and '''exudation'''
**Deposited complexes cause '''inflammation''' and '''exudation'''
**This leads to characteristic '''oedema''' as fibrin-rich serum escapes to intercellular spaces
**This leads to characteristic '''oedema''' as fibrin-rich serum escapes to intercellular spaces
*For more, see [[Intestines Granulomatous Enteritis - Pathology#Feline Infectious Peritonitis|here]]
** [[Intestines Granulomatous Enteritis - Pathology#Feline Infectious Peritonitis|'''Pyogranulomas''']] can develop in major organs as a result of the immune response and the body's failure to clear away excess neutrophils
*Cats previously exposed to coronavirus (and therefore with circulating antibody) may be at greater risk as they are more susceptible to taking up virus into mononuclear cells
*Cats making a biased Th-1 response are more likely to evade infection, whereas cats making a balanced response are at moderate risk and cats making a biased Th-2 response are at greater risk, as the virus is best tackled by cell mediation and not antibody
*Cats compromised by '''immunosuppression''' (either iatrogenic or disease-related) are at a greater risk of developing FIP
Clinical signs:
*Chronic weight loss
*Anorexia
*Pyrexia
*Depression
*Fluid in the abdomen, thorax or pericardium symptomatic of '''wet, or exudative FIP'''
*Granulomatous change in the organs symptomatic of '''dry, or nonexudative FIP'''
Can be shown to cause:
*Uveitis
*Hydrocephalus
*Neurological symptoms, such as ataxia or seizures
*Chronic diarrhoea
====Epidemiology====
====Epidemiology====
*FECoV is '''endemic worldwide''', with the majority of cats showing a subclinical seroconversion
*'''Orofecal, aerosol, and contact''' transmission
*Particular concern for '''catteries''' and homes with '''multiple cats'''
*FIP arises from a '''mutation of FECoV''' (in 5-10% of chronically infected cats) and not directly from cat to cat
====Diagnosis====
====Diagnosis====
*Serology is impossible as most cats will have antibody to FECoV
*Clinical signs
**FIP should be suspect in all cases of chronic weight loss or recurrent fever unresponsive to antibiotics, particularly in multiple cat situations
*Simple serology is impossible as most cats will have antibody to FECoV
*However, 4 indicators can be used to cross reference:
**High FECoV Ab titres
**Low albumin:globulin ratio in plasma/ascites (globulin levels rise in FIP)
**High levels of glycoprotein alpha 1-acid glycoprotein (AGP)
**Low white cell counts
*FIP antigen detection by '''immunofluorescence''' in macrophages gives a definite positive diagnosis
*PM: look for characteristic lesions in vascular immune complex disease and lymphoid infiltration
====Control====
====Control====
*Conventional vaccination is counterproductive as antibody worsens infection
*A non-systemic vaccine (Primucell) is available outside the UK
**Temperature-sensitive mutant
**Replication confined to nasal mucosa, providing local immunity and cell-mediated immunity
**Cannot protect cats already infected with FECoV
**Kittens must be isolated until old enough to vaccinate at 16 weeks
*Antibody tests are available to certify "FECoV-free" cat houses