Flashcards in Feline infectious Peritinitis and coronavirus Deck (25)
Cause of feline infectious peritonitis
1. caused by a coronavirus (FCoV)
2. NOT zoonotic
3. Cat with FCoV then develops FIP. NOTE, not all cats infected with FCoV develop FIV (more common lots of cats e.g. breeders)
How is FCov shed?
SHED in FAECES
PICKED up ORALLY
4. infection with FCoV in young kittens via faecal oral transmission
What is virus classification based on?
- Genome (DNA or RNA)
- Enveloped or not
- Genome sequence similarity
- Number and sense of RNA/ DNA strands
Corona virus Genome and what it means
1. RNA genome inside a lipid envelope
2. Having RNA genome means these viruses can mutate and evolve quickly
3. o Labile in the environment (readily/ continuously undergoing chemical physical or biological change)
Corona virus, enveloped or not?
Lipid envelope derived from hsot cell. It is essential for infectivity byt fragile. Means coronaviruses are generally short lived in environment and relatively suseptible to soap and alcohol based disinfectants
NEVER say "your cat has coronavirus" ensure say FELINE
1. LArged enveloped RNA virus -
2. 2 types: Feline infectious peritonitis virus and feline enteric coronacirus
Not all cats infected with coronavirus develop into feline infectious peritonitis. What deos it depend on?
Depends on things similar to feline leukaemia virus
o virus strain ‘biotype’
o dose of virus
o immune status of cat and if can amount a good immune response
o (route of infection)
How we think feline enteric coronavirus works
if infect, some no clinical signs but they pass it on – endemic . There is a in cat mutation which leads to FIP. Cats with FIP DIE.
Do you get outbreaks of FIP
no becuase FIP isn't faecally shed (FCoV is)
Cat ONLY gets FIP when infected with FCoV and mutation occurs to cause FIP
When do we most often see FIP
Breeders - lots of cats housed together
Pathogenesis of FIP
1. Cat, oronasal infection = feline corona virus
2. Replicated locally in tonsil, intestinal epithelium
3. May get mild disease
4. Sporadic mutation = FIP = allows virus to get in macrophages
5. Once in macrophage = all over body
6. then one of 3 outcomes:
a) Good cell mediated immunity, cat recovers
b) partial CMI, cat develops DRY FIP
c) poor CMI, cat develops WET FIP
What is Dry FIP?
1. clinical signs- fluctuating, unresponsive fever
2. anorexia, depression, lethargy
3. signs dependant on organ involved (abdominal? CNA? eyes?)
4. Jaundice, ataxia, paresis, behavioural changes, iritis, uveitis etc
What is wet FIP and clinical signs
• Invariably fatal - rabies
• Accumulation of fluid within the body cavities e.g. abdomen
• Depression, Inappetance, lethargy, weight loss, swelling of abdomen, jaundice, hepatomegaly, dyspnoea, muffling of heart sounds. Depends where fluid accumulates
• Fluctuating, unresponsive, fever
What kind of disease is FIP?
1. an immune complex disease
- immune complexes deposit in walls of small blood vessels leading to complement activation and vasculitis = inflammatory response = oedema
- Ab binds to virus, ENHANCING uptake of antigens by macrophages
- meaning Ab aren't particularly helpful!
- Cats that don't have antiviral antibodies don't develop FIP = why vaccination is particularly challenging
Diagnosis of FIP
• HUGE CHALLENGE
• Definitive diagnosis – histopathology – demonstrating characteristic lesions
• Pre-mortem diagnosis (biopsy) often by a combination of clinical signs, examination of fluids, clinical pathology and FCoV serology
• If there is fluid in body cavities to be found then it should be identified and collected if at all possible OR biopsy legions – best diagnosis
What is an important tool used in FIP diagnosis
IMAGING to identify fluid
What will results of haematology adn blood biochem be?
• Mild non-regenerative anaemia
• Hyperproteinaemia – raised globulins
• Albumin/globulin ratio decreases
• Increased liver enzymes, bilirubin and urea
So diagnosing a cat (with FIP) collected fluid. What does it look like?
• Straw coloured
• High protein content (more globulin than albumin)
• Froths if shaken
• Clots on standing
diag for what?
how to do?
2. Not 100% accurate
3. V easy to do and quick result
4. Drop small drop of fluid from cat into vinegar solution
5. FIP = stable clot in vinegar which gently falls down in vinegar
6. Not FIP = dissolves in vinegar
7. Shows that if neg result
Feline coronavirus serology.
What are you measuring?
What does positive result indicate?
• Measurement of antibodies by IF or ELISA
• Antibody positive does not mean the cat has FIP, just means has been exposed to FCoV
• Can be used in addition to other diagnostic procedures
Remember no diagnosis tool is 100% perfect
How does serology for FIp work?
1. Quantitative way
2. Grow your cells in cell culture infected with FCov
3. Antibodies from cat, will adhere to Ag if present
4. Detect these Ab with another labelled Ab
5. Each well has cells infected with corona virus in.
6. Serum from cat has been diluted, 1 in 10, 1 in 20 1 in 40 etc etc
7. Fluorescence = sufficient Ab in to test positive. As dilute = not enough Ab to cause fluorescence = end point
8. Bigger end pojnt = more Ab in original sample
9. Generally cats with FIP have bigger titres of Ab
10. Not 100%
How is nucleotide sequence alignment useful with viruses?
• Based on complete genome
• It shows the relatedness of the different virus strains. The closer these virus strains are together within this tree the more related they are.
Treatment or FIP
No effective treatment for FIP, invariably fatal
1. interferon may be something but not been credited yet
How to control FCoV and FIP in infected households
• 75-100% of cats from breeding households seropositive so ask owner where got cat from
• 1 in 3 queens will transmit virus to her kittens
• faecal shedding – oral infection
• Kittens have lost MDA by 8 weeks – kittens will have seroconverted by 10 weeks of age
Prevent infection in kittens:
isolate queens 1 to 2 weeks prepartum
early wean kittens
strict isolation of kittens
check kittens are seronegative from 10 weeks of age after MDA have declined.
• hygiene – adequate numbers of litter trays
• reduce numbers of cats maximum of 8 to 10 breeding adults – reduces stress and transmission
• reduce stress
• reduce numbers of kittens
• keep households stable – reduces stress which lowers immunity allowing viruses to replicate and mutate more