Feline Immunodeficiency Virus

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Feline Immunodeficiency Virus

• By Neva DeCoux, Michelle Kwok

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Etiology
Feline immunodeficiency virus (FIV) is a type of
lentivirus ("slow virus") classified by a long
incubation period (may last as long as 6 years)
that slowly develops into the disease. It is in
the same retrovirus family as feline leukemia
virus (FeLV) and human immunodeficiency virus
(HIV). It attacks the immune system, and as a
result, the cat is unable to fight off various
infections and cancers. Approximately 2.5 of
cats in the United States are infected with FIV.
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Cause

• The virus, a lentivirus, interacts with
  lymphocytes, changing their ability to function
  normally in the immune response process.
• The resulting lymphopenia, loss of memory cell
  function, and decrease in antibody production
  from T-cell stimulated lymphocytes leaves the cat
  open for opportunistic infection.

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Retroviruses

• Retroviruses are species-specific. This means a
  feline retrovirus like FIV will only infect cats
  a human retrovirus such as HIV will only infect
  humans.
• Retroviruses are made up of RNA. In the host, the
  RNA is transcribed into DNA and incorporated into
  the DNA of the hosts cells.
• Retroviruses are fragile, being easily
  inactivated by ultraviolet light, heat,
  detergents, and drying.

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History of disease

• It was first discovered during the investigation
  of a disease outbreak in a previously healthy
  colony of rescue cats at UC Davis in 1986 by
  immunologists Janet Yamamoto and Niels Pederson
• The colony had been showing similar signs to
  people with acquired immunodeficiency syndrome
  (AIDS) caused by human immunodeficiency virus
  (HIV) infection.
• Yamamoto started working on a vaccine for FIV at
  UC Davis.

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Signalment

• Vulnerable at any age
• Outdoor, free-roaming felines
• are at greater risk
• Male felines are 1.5 to 3 times more likely to
  become infected then a female feline.
• Is rare in catteries
• More predominant in free-roaming aggressive male
  cats due to transmission by bite wounds
• Infects domestic cats, and can also infect wild
  felines including snow leopards, lions, tigers,
  jaguars, Florida panthers, and bobcats.

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Roaming Male Feline
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Feline with FIV

• - Feline Male was diagnosed to be FIV positive.

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Transmission
The primary modes of FIV transmission are deep
bite wounds and scratches, where the infected
cat's saliva enters the other cat's bloodstream.

• Casual, non-aggressive contact does not appear to
  be an efficient route of spreading FIV.
• On rare occasions infection is transmitted from
  an infected mother cat to her kittens, usually
  during passage through the birth canal or when
  the newborn kittens ingest infected milk
• FIV transmission in utero or through the mother's
  milk is very rare. It could possibly occur if the
  queen is infected during pregnancy or while
  nursing the kittens.
• Queens infected with FIV prior to the pregnancy
  usually have non-infected kittens.

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Transmission

• Sexual contact is not a major means of spreading
  FIV.
• Although FIV is a lentivirus similar to HIV (the
  human immunodeficiency virus) and causes a
  disease in cats similar to AIDS (acquired immune
  deficiency syndrome) in humans, it is a highly
  species-specific virus that infects only felines.
  

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Clinical signs

• Poor coat condition and persistent fever with a
  loss of appetite are commonly seen.
• Lethargy
• Inflammation of the gums (gingivitis) and mouth
  (stomatitis) and chronic or recurrent infections
  of the skin, urinary bladder, and upper
  respiratory tract are often present.
• Persistent diarrhea
• Slow but progressive weight loss is common,
  followed by severe wasting late in the disease
  process.
• Various kinds of cancer and blood diseases are
  much more common in cats infected with FIV, too.
• In unspayed female cats, abortion of kittens or
  other reproductive failures have been noted.
• Some infected cats experience seizures, behavior
  changes, and other neurological disorders.

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Clinical Signs

• Febrile episodes
• Lymphadenopathy (chronically swollen lymph nodes)
• Persistent infections unresponsive to treatment
• Weight loss
• Gingivitis
• Ocular lesions
• Slow-healing traumatic wounds
• Behavior abnormalities
• Chronic upper respiratory infections
• Anemia

Pansystemic disease
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Diagnostic tests and Expected results

• Immunoblotting
• Uses anti-bodies to detect HIV related proteins

• PCR (polymerase chain reaction)
• Detects the virus itself
• Very useful for detecting infection in kittens
  born from the FIV positive mother 
• Check for false positives

• Elisa (Enzyme-linked immunosorbent assay)
• Detects anti-FIV antibodies
• Most common
• Rapid and reliable method
• Does not work well with very early infection
• False positive is very rare
• Repeat test to be sure

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Diagnostic Tests

• ELISA test (enzyme-linked immunosorbent assay)
  will be positive
• -It is possible to get false positive or false
  negatives from these results for the following
  reasons

False Positive False Negative
Kittens born to FIV infected mothers may have received antibodies from their mothers milk. This doesnt mean that the kitten has FIV, just that it has received antibodies to FIV. Kittens that test positive should be re-tested at a later date. It usually takes several weeks for the antibodies for FIV to appear in the blood, if a cat is tested prior to this it will show a negative test result.
If a cat has received the FIV vaccine the test results will show up positive. If the cat is in the later sages of infection it may not be producing antibodies.
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Elisa Test ? PCR Test
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Diagnostic Test cont.

• A FIV PCR (polymerase chain reaction) test is
  available in some commercial laboratories. PCR
  detects the presence of the FIV virus in the
  blood.
• Western blot test or IFA (Immuno-Fluorescent
  Antibody Test) If a cat has tested positive to
  FIV it is sometimes recommended to follow up with
  either a Western Blot Test or an IFA test.
• If your cat has tested positive to FIV but you
  are not sure if it has had the vaccine, or want
  to be sure it does/doesn't have the virus then
  you may be able to request a PCR (polymerase
  chain reaction) test, which will be able to
  detect the presence of FIV DNA in the blood.
• Urinalysis elevated protein levels
• CBC (stage 3) anemia, lymphopenia, neutropenia

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Western Blot Test
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Recommended Treatment

• No treatment to eliminate the virus
• Depends on the proper health management
• There are some anti-viral medications but they
  are not 100 effective in improving the immune
  system

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Treatments

• FIV is treated symptomatically.
• Medications
• -Antibiotics for secondary infections
• -Appetite stimulants
• -Corticosteroids
• -Immune modulators
• Dental extractions with chronic gingivitis and
  stomatitis
• Some also require nutritional support, fluid
  therapy, and dental care.

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Prognosis

• It is not possible to determine how long a FIV
  positive feline will live, but with proper care
  and supportive therapy they can live a full life.

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Prognosis

• The outlook for cats that show severe, chronic,
  multiple signs of disease is poor.
• If clinical signs have developed only recently
  and are not severe, there is a reasonable
  prospect of improvement with treatment, which may
  be maintained for some time.
• Greater than 50 of infected felines remain
  asymptomatic within 2 years after diagnosis
• Treatment usually consists of supportive therapy,
  often antibiotics, possibly coupled with
  antiviral therapy.
• Felines in the terminal stage of the disease
  survive less then one year.
• For kittens can detect maternal AB hence re-test
  after 6 months.
• Average life span from diagnosis to death is
  roughly around 5 years.

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Pathologic lesions

• University of Bristol School of Veterinary
  Science Study
• A range of tissues from a total of 17 cats
  naturally infected with the feline
  immunodeficiency virus was examined
  histologically.
• In 11 cases, chronic inflammatory lesions were
  present in various tissues including, most
  commonly, the intestine, brain and lung.
  Extensive inflammation in the intestinal wall was
  present in seven of the cats.
• No particular bacterial organisms were
  demonstrated in these inflammatory lesions. A
  range of changes was present in the lymph nodes,
  including hyperplasia, atrophy or a mixed
  pattern. Erythrophagocytosis was a consistent
  feature.
• Some present with dysplastic nodes characterized
  by follicular atrophy (wasting away of the
  follicles), paracortical cell depletion, and
  fibrosis (excess fibrous connective tissue).

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Pathologic lesions of disease

• The most commonly occurring lesions (seen in 91
  of infected cats) were thymic atrophy,
  generalized lymphoid hyperplasia, and bone marrow
  hyperplasia.
• The second most common lesions were splenic
  lymphoid hyperplasia and thymic follicle
  formation (7883 of cats).
• A third set of miscellaneous lymphoid and mucosal
  lesions was confined to 30 of cats.

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Prevention

• Isolate affected cats.
• Keep unaffected cats away from feral cats.
• A vaccine for FIV currently is available
• - may test positive for FIV at a later date
• Spaying and neutering outdoor cats can limit
  exposure by decreasing aggressive behaviors.
• - especially males

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FIV Vaccine

• Cons
• Does not provide full protection against all
  strains.
• Since it is a killed virus, adjuvants are used
  which carry the possibility of vaccine associated
  sarcomas forming.
• Vaccinated feline will always be FIV positive.
  Can be a problem if lost and placed in a shelter.

• Pros
• Provides 82 protection against strain A.

No blood test can differentiate between a
vaccinated cat and a truly infected FIV positive
cat.
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Client Education

• Educate about the virus and vaccine
• FIV is a progressive disease
• FIV infected felines should be confined indoors
  to prevent the spread of the virus
• FIV infected felines should be spayed or neutered
• Should be fed complete and balanced nutritional
  diet
• Uncooked food should not be fed (Ex raw meat,
  eggs and unpasteurized dairy products)
• Wellness visits for FIV infected felines should
  be scheduled with your veterinarian at least
  every six months
• Close monitoring of health and behavior 
• Test all new additions to the cats household.

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References

• http//www.vet.cornell.edu/fhc/brochures/fiv.html
• http//www.knowyourcat.info/health/fiv.html
• http//www.fivprognosis.org/owners.html
• http//www.peteducation.com/article.cfm?c11316a
  id213

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References

• Common Diseases of Companion Animals
• Veterinary Technicians Daily Reference Guide
• www.vet.cornell.edu
• www.merckvetmanual.com
• www.cat-world.com.au
• http//gateway.nlm.nih.gov
• http//fabcates.org
• http//sciencedirect.com