Calicivirus VS-FCV
Dr. Gary D. Norsworthy is a San Antonio-based feline practitioner and a widely recognized author, editor and lecturer on issues relating to feline health. He recently talked with www.dvmvac.org about virulent FCV, a dangerous new virus that is frequently fatal in cats.
DVMvac.org What is VS-FCV?
Dr. Norsworthy It's a mutation of the calicivirus, one of two major respiratory viruses typically found in cats. The mutated version has shown up in about seven or eight locations in the United States, since it was first identified in Northern California in 1998. VS-FCV also has appeared in the United Kingdom.
DVMvac.org Where has it surfaced in the United States?
Dr. Norsworthy Twice in California, once in the north and once in the south; Pennsylvania; Massachusetts; Tennessee; Nevada and North Carolina.
DVMvac.org What makes the virus dangerous?
Dr. Norsworthy The typical calicivirus is usually not fatal. However, the mutated form has a very high mortality rate - 40 to 50 percent - and it's very easily transmitted from one cat to another. It can be transported on articles of clothing, shoes or hands and may be found on commonly touched objects, such as keyboards or doorknobs. As a result, it spreads very quickly within facilities whenever it occurs.
DVMvac.org How quickly is it spreading across the United States?
Dr. Norsworthy So far, it has been isolated. All of the outbreaks to date have occurred in clinics or shelters. But that's not to say it couldn't spread into the wider population. I recently gave a lecture on calici at the Western Veterinary Conference in Las Vegas. After the lecture, a veterinarian came up to me and described a situation in his practice. It only involved two cats, which were from the same household. They showed very similar clinical signs indicating VS-FCV, and both cats died. So, that effectively put an end to the epidemic, since there were only two cats involved. The fact is there may have been many other unreported outbreaks.
DVMvac.org What are the symptoms of VS-FCV?
Dr. Norsworthy It starts off looking like a regular respiratory infection with loss of appetite, sneezing, discharge from the eyes and nose and ulcers in the mouth. This is pretty typical for a traditional calici infection. However, many times the fever will exceed 105 degrees, which is not typical for most calici infections. In addition, many of these cats develop edema around the head, legs and feet, and they lose hair in various locations. They also have inflammation in the skin, on the ears and around the lips and nose. Some cats then experience respiratory problems with fluid pulmonary edema or pleural effusion. But with many cats, the virus hits so rapidly these symptoms don't even show up, and they die very quickly.
DVMvac.org So what's the most important thing veterinarians should watch for?
Dr. Norsworthy They need to look for problems that start as a respiratory infection. The fever gets extremely high, more than 105 degrees, and the cat starts developing edema in the head or the limbs. It should be obvious at that point this is something other than a typical respiratory infection. Basically, it starts like a typical calici infection and then just accelerates from there.
DVMvac.org What are your greatest fears with respect to this disease?
Dr. Norsworthy There are three: First, a large number of these cats die and those that do not die may take several weeks to return to normal. Second, the loss of a pet is always devastating to the owner. Finally, there are implications to me as a practice owner. If the disease occurs in my practice, it will likely result in several weeks of bedlam that will only subside once the epidemic is over. Various measures have been recommended to try to stop it from spreading, including disinfecting every surface in the hospital and, in effect, closing your doors for a couple of weeks. You can't let any animals in or out.
Having to close for a week or two can be economically devastating for a practice. And even if you get the disease stopped, the outbreak may be reported in the newspaper, and there could be widespread concern among pet owners for fear the virus is still lingering. So, it can be really serious.
DVMvac.org Is there any preventative regime?
Dr. Norsworthy There have been vaccines for the calicivirus for a number of years, and they are reasonably effective, but at this point, there is not yet a vaccine for the virulent systemic strain. However, one is under development, and I believe it should be available later this year. As I understand it, it will be included in the vaccine we now give cats for calicivirus, so it will provide a broader-spectrum of coverage.
DVMvac.org Do you think most veterinarians are aware of VS-FCV and are taking the threat seriously?
Dr. Norsworthy I imagine, after this new vaccine is released, some veterinarians will say, "Well, this virus happens rarely, so I don't think this is something I need to worry about." I would say two things in response to that: Number one, if it hits your practice, it's an absolute disaster - for the cats, for the clients and for your business. Number two, I've been in practice 33 years and have never seen a case of rabies in a dog or a cat. I hope to finish my career and still be able to say I've never see a case of rabies. Nonetheless, I vaccinate cats virtually every day to keep them from getting rabies. So, just because it's a relatively rare disease doesn't mean we shouldn't vaccinate to keep it that way.
DVMvac.org Speaking of vaccines, what is the current state of needle-less delivery for vaccinations?
Dr. Norsworthy There is one vaccine which has been released using a needle-less injection system. It's for feline leukemia virus, and it is the first time this particular delivery method has been used in cats. So there's not much of a track record on it. Unfortunately, this particular vaccine received rather limited clinical trials before it was released. The challenge study was done at 28 and 29 days following vaccination. So, that tells us that it's good for 28 or 29 days, but whether it's good beyond that is just speculation.
DVMvac.org How does the delivery work?
Dr. Norsworthy An injector gun is placed against the skin, and then, the vaccine is literally blown through the skin.
DVMvac.org Do you think this approach holds promise?
Dr. Norsworthy I think there's going to be rather limited use for it. I haven't used it, but in my lectures, I frequently ask people in my audience if they've used this system and, if so, how cats react to it. And virtually across the board, people are saying that 25 to 50 percent of the cats will jump -- often right off the exam table - once the unit is discharged.
DVMvac.org Why is that?
Dr. Norsworthy There are two possibilities: One is pain, and the other is the fact the gun is fairly noisy. Regardless, many owners will perceive you have harmed their cat in some way. Perceptions like this often cause cat owners to seek a new veterinarian.
DVMvac.org What are the benefits of using needles?
Dr. Norsworthy We know it's a proven system that works. With a little bit of practice, a veterinarian can usually give an injection in a way that the cat doesn't even know that it's happened.
DVMvac.org We're all aware of the controversy surrounding adjuvants, but why do you think they are important in the development of effective vaccines?
Dr. Norsworthy The standard vaccines in which adjuvants are used are killed products to which the body's immune system doesn't react very strongly. Therefore, the duration of immunity produced by the vaccine is relatively short. The adjuvant stimulates or provokes a response from the immune system, thereby causing a stronger reaction to the killed virus and creating a longer duration of vaccine immunity.
DVMvac.org Thank you, Dr. Norsworthy.