a) The VS-calicivirus is a mutant strain of the common feline calicivirus.
b) It causes disease that is much more severe and usually fatal, especially to adults.
c) Common calicivirus vaccines offer no protection, but they do not predispose the cat to getting a VS-calicivirus infection.
d) The common calicivirus disease
i) It is an upper respiratory infection primarily affecting the nose.
ii) Clinical signs
(1) Sneezing, fever (mild), lethargy, anorexia, nasal discharge (serous to purulent), and oral ulcers (primarily on the tongue.).
The distinguishing feature (from a Herpesvirus infection) is oral ulceration. The feline Herpesvirus often causes corneal
2) First outbreak
a) Occurred in 1998 in Northern California.
b) Occurred in a veterinary practice and a research laboratory.
c) 33 and 50% of infected cats died.
d) It was spread by contaminated fomites.
e) Clinical signs
i) Began with typical URI signs then ...
ii) Fever, facial and limb edema, hair loss and ulcerative dermatitis of the face and feet, sudden death.
3) Southern California (Los Angeles) outbreak
a) Occurred in three veterinary practices and one rescue organization. They were located geographically close to each other
and employed many common staff members, who circulated between the four facilities.
b) Transmission between the four facilities was due principally to fomites and cat-to-cat contact involving cats with clinical
and subclinical infections.
c) Involved 54 cases.
d) The common clinical signs were fever (81%), nasal discharge (30%), oral ulcers (46%), and limb or facial edema (52%).
e) The less common signs were dyspnea (17%), dermatitis of the face and feet (17%), conjunctivitis (11%), icterus (11%), and
pleural effusion, diarrhea, vomiting, and hemorrhage in the skin.
f) 15% of the cats had mild clinical signs; 15% of the cats had moderate clinical signs; and 70% of the cats had severe clinical
signs that included edema, dyspnea, and death. 63% of the cats with severe clinical signs died.
g) The time from exposure to the onset of clinical signs averaged four days (1-12 days).
h) 59% of the cats over one year of age died; the fatality rate of cats less than six months old was in frequent.
4) Common components of the VS-Calici outbreaks
a) An index case could be identified (5/6), usually a shelter or rescue cat.
b) They have occurred principally in adult, vaccinated cats that had received herpes-calici vaccine.
c) Spread has occurred rapidly be a fomites on employees or clients.
d) They have not spread out of the facility into the community.
e) Each outbreak has resolved in about two months.
5) VS-Calici Shedding
a) In feces
b) In sloughed skin and hair
c) In nasal, ocular, and oral secretions
d) Viral shedding occurs intermittently for ~4 months after resolution of clinical signs.
6) Typical Clinical Signs
a) Begins with classic calicivirus URI signs
ii) Nasal and ocular discharge
iii) Oral ulceration