Difference between revisions of "Feline Infectious Peritonitis"
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(New page: {{unfinished}} {{toplink |linkpage =Viruses |linktext =VIRUSES |sublink1=Coronaviridae |subtext1=CORONAVIRUSES |pagetype =Bugs }} <br> ====Antigenicity==== *FIP occurs in 5-10% of cats i...) |
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*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 | ||
| − | * | + | ** [[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==== | ||
| − | * | + | *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 | ||
Revision as of 15:24, 18 October 2008
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This article is still under construction. |
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Antigenicity
- FIP occurs in 5-10% of cats infected with Feline Enteric Coronavirus (FECoV), which is quite common
- It is therefore antigenically indistinguishable from FECoV
Hosts
- Domestic and wild cats
Pathogenesis
- 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
- FECoV replicates in the gut, but FIP spreads systemically in the circulation
- FIP gains ability to replicate in monocytes and macrophages
- Almost invariably fatal
- Failure of the immune system to clear antibody-antigen complexes leads to immune-mediated disease
- Deposited complexes cause inflammation and exudation
- This leads to characteristic oedema as fibrin-rich serum escapes to intercellular spaces
- 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
- 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
- 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
- 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