Feline Herpes and Calicivirus Flashcards
1
Q
What is the structure of of Feline Herpes Virus-1 (FHV-1)? How sturdy as
A
- Enveloped, double-stranded (ds)-DNA virus
- Relatively fragile and can survive for up to 18h in a damp environment, less in dry conditions
- Highly susceptible to common disinfectants
2
Q
How many serotypes are there for FHV?
A
1, field strains are relatively homogenous
3
Q
What causes the majority of URIs in cats?
A
- FHV-1
- Feline calicivirus
4
Q
What age do cats normally get FHV-1?
A
- Most infected between 8-12 weeks old
- Primary infection CAN occur in older kittens and adults
5
Q
What anatomical structures does FHV-1 infect
A
- Nasal mucosal lining (& nasal turbinates)
- Tonsil/pharyngeal
- Conjunctiva
- Cornea
- Rarely, epidermis, mainly on the face
6
Q
What are the clinical signs of a FHV-1 infection
A
- URI
- ocular disease
- rarely - facial dermatitis
7
Q
How is FHV-1 shed?
A
- ocular/nasal secretions
- saliva
8
Q
What is the incubation period for FHV-1?
A
2-5 days
9
Q
How long does a FHV-1 infection last?
A
- Clinical signs usually resolve in 2 - 3 weeks
- some develop chronic diseases
- Secondary bacterial disease may occur
10
Q
What symptoms are common with conjunctivitis?
A
- Hyperemia
- Chemosis
- Epiphora
- blepharospasm
- bacterial co-infection may occur
11
Q
What is the concern with corneal ulcers?
A
- superficial corneal ulcer can progress to:
- stromal corneal ulcer
- descemetocele
- perforation
12
Q
What is the hallmark of FHV-1?
A
- Ability to establish latent infection
- Virus lies dormant within a cell following acute disease
- Pathogenesis:
- Acute primary infection of alpha-herpesvirus ⇢ latency (sensory nerve ⇢ trigeminal nerve ganglion) ⇢ Reactivation (stress/spontaneous)
13
Q
How common are latent FHV-1 infections?
A
- 82% of infected cats
- Not all experience virus reactivation
14
Q
What can reactivate a FHV-1 infection?
A
- Stressful conditions or steroid adminiastration
- steroid: 69% shedding in 2-7 days
- Rehousing: 18% shedding
- Spontaneous 29% within 8 months (stressor unknown)
- Stressors:
- corticosteroid
- co-infection
- parturition/lactation
- change of housing, etc
15
Q
What is the major source of environmental contamination with FHV-1
A
- Acutely infected cats (primary infection)
- Latently infected cats experiencing reactivation
16
Q
What impacts does chronic FHV-1 cause?
A
- Scarring of nasal turbinates from FHV-1 (or FCV) and secondary bacterial infection ⇢ chronic rhinitis
- Scarring of ocular tissue ⇢ chronic ocular disease
17
Q
How is FHV-1 transmitted? what contributes to its contagiousness?
A
- Direct contact
- Bodily fluids > aerosol
- Relatively fragile outside the host, but HIGHLY contagious
- Young cats predisposed (maternal immunity wanes)
- Majority of cats are chronic shedders (weeks or longer) even after clinical signs have resolved
- majority become latently infectant and can have recurrent disease
- Short immunity - reinfection can occur
18
Q
How is FHV-1 diagnosed?
A
- Usually based on hx and clinical signs
- young kitten showing URI and ocular signs
- rapidly spread among cats
- Diagnostics: for severe or chronic cases
- Virus detection by isolation or PCR
- Ocular, nasal, and/or oropharyngeal swabs
- Positive can be incidental - virus reactivation without clinical signs, recently vaccinated cats
- False negative: intermittent virus shedding, inadequate handling of samples, lab errors, etc
- Virus detection by isolation or PCR
-
presence of virus and clinical signs are poorly correlated
- use caution when interpreting diagnostic tests
19
Q
What is the FHV-1 vaccination? What effects does it have?
A
- Core vaccine (Feline panleukopenia, FHV-1, FCV, rabies, and FeLV)
- Attenuated live (+/- adjuvanted) and inactivated vaccines given parentally
- Attenuated live intranasal vaccine: faster onset of protection within 4 - 6 days
- Vaccinations can decrease virus shedding and clinical signs but does not necessarily prevent infection, latency or reactivation
- Relatively efficacious to all field strains but disease still can occur due to inadequate vaccination, high virus challenge dose, immunocompetence status, etc
- Prevention and control of FHV-1 requires vaccination + management
20
Q
How is a FHV-1 infection treated?
A
- Self-limiting - Supportive therapy
- Severe signs may require antiviral drug treatment
- No licensed antiviral dugs specifically for FHV-1
- Human herpes antiviral drugs for oral use (nucleoside analogues - ie famciclovir) - controlled studies required
- Ophthalmic herpes antiviral dug for humans (cidofovir, trifluridine, idoxuridine, vidarabine) Efficacy is not well known
- L-lysine- thought to compete with arginine, an AA essential for FHV-1 replication, however conflicting reports on the effectiveness. May increase disease severity and viral shedding
21
Q
What is the Family and Genus of Feline Calicivirus?
A
- Family Caliciviridae
- Genus vesivirus
22
Q
What is the structure of FCV?
A
- sense ssRNA virus
- Non-enveloped
- 38nm particle
23
Q
How many serotypes of FCV are there?
A
- One serotype
- diverse field strains w/ varying antigenicity and pathogenicity
24
Q
How stable is FCV?
A
- Can survive for weeks - months in dry conditions
- up to 1 month on dry surface at room temperature and longer in colder conditions
- Resistant to many commonly used disinfectants
- Effective: 5% bleach (1:32 dilution) peroxygen compounds, glutaraldehydes
- NOT: quaternary ammonium
25
Q
How is FCV transmitted?
A
- Direct contact and fomites - primary
- Highly contagious
- Most cats are chronic shedders for ~30 days +
- some shed for months - years w/out clinical sings
- Short immunity - reinfection can occur
26
Q
What are the types of FCV infections?
A
- Upper respiratory signs/oral lesions
- High morbidity, low mortality
- Very common
- Systemic, virulent FCV infection
- High morbidity, high mortality
- very rare
27
Q
What is the incubation time for URI calicivirus?
A
2-10 days
28
Q
What are the clinical signs of FCV infection?
A
- Fever
- Lethargy
- Any of:
- Upper respiratory signs: conjunctivitis and rhinitis, usually milder, but can be as severe as FHV-1
- Oral vesicles and ulceration - gums, tongue, palate, lips, nasal philtrum - hypersalivation
- Dermatitis - skin and nasal ulceration
- Acute arthritis: transient lameness is associated with some FCV strains
- occurs a few days of weeks after the acute oral/respiratory signs
29
Q
What is Lymphoplasmacytic stomatitis?
A
- Different form stomatitis caused by calicivirus
- Aka: chronic plasma cell gingivitis and pharyngitis, plasma cell stomatitis, chronic ulceroproliferative faucitis
- Chronic inflammatory disease:
- chronic ulceroproliferative lesion around the oral fauces or the oral cavity leading to the pharynx
- Lesion densely infiltrated with plasma cells and lymphocytes
- chronic ulceroproliferative lesion around the oral fauces or the oral cavity leading to the pharynx
- Cause unknown
- atypical and persistent immune response towards viral, bacterial, or environmental antigen is implicated
30
Q
How is FCV diagnosed?
A
- Based on hx and clinical sings
- Dx test: Virus isolation or RT-PCR form oral/nasal secretion swab samples
- May be useful to identify FCV as a cause for URI in shelters because FCV can persist in the environment
- Presence of virus and clinical signs are poorly correlated - use caution when interpreting dx tests
31
Q
How is FCV infection treated?
A
- Self-limiting = supportive care for severe cats
- No antiviral drugs
32
Q
What type of vaccine in the FCV vaccine? What affects does it have?
A
- Core vaccine
- Attenuated or inactivated vaccines given parentally
- Intranasal attenuated live vaccine
- One FCV serotype but high antigenic variability among field isolates
- Vaccine does NOT protect equally against all strains
- Can decrease virus shedding and clinical signs buts does not necessarily prevent infection or chronic carrier status
33
Q
What is the Virulent systemic calicivirus infection (vs-FCV)?
A
- Reported in the US and EU since 1998
- High fatality rate up to 67%
- Incubation period 1-5 days
-
Rare
- Almost exclusively outbreaks occur in shelters, rescues or catteries
- not a disease of household cats
34
Q
When should Vs-FCV be suspected?
A
- Hx: recent exposure to a multi-cat environment or recent addition of a cat; more than one cat affected; fully vaccinated, otherwise healthy adult cats affected
- General signs of FCV followed by severe systemic signs:
- Death in some cats
- Signs of vasculitis (facial edema and limbs) not explained by other causes
- Liver necrosis on biopsy or necropsy
- More severe in adults than kittens
35
Q
How is Vs-FCV diagnosed?
A
- Serology and virus detection in nasal, conjunctival or oropharyngeal swabs have limited use because:
- No genetic markers for vs-FCV
- FCV infection is widespread
- Necropsy - rule out other causes
- Gold Standard: IHC on internal organs
36
Q
How is a vs-FCV infection managed?
A
- Outpatient treatment if possible - avoid viral transmission in clinics
- Strict isolation if hospitalized
- Thorough cleansing of environment/clothing/equipment
- No new cats into the environment until the outbreak is under control
- Recovered cats may shed the viruses for months
37
Q
is there a vaccine for vs-FCV?
A
- Core FCV vaccines have limited efficacy against vs-FCV
- Vs-FCV vaccine - currently not recommended
- Protects from homologous vs-FCV strain, but there are different field strains of vs-FCV
38
Q
Compare and contrast FCV and FHV-1
A
- FHV-1:
- Respiratory signs
- Conjunctival and corneal lesions
- Rhinitis with sneezing, bilateral serous nasal discharge
- Clinical signs can be more more severe:
- Obstructed nares, matting of eyelids, kittens - open mouth breathing, anorexia, dehydration, pneumonia
- Dermatitis
- Can cause oral ulcer
- Fever, anorexia, lethargy with any if the above signs
- FCV:
- Highly variable combination of signs (strain dependent)
- Respiratory signs
- Oral and nasal ulcer
- transient lameness
- Pneumonia
- Conjunctivitis
- Dermatitis
- Fever, anorexia, lethargy with any of the above signs
- Highly variable combination of signs (strain dependent)
