Feline Immunodeficiency Virus

For PCR testing, samples of blood are taken or swabs of oropharyngeal or conjunctivae mucosae are taken by cotton swabs (are provided by laboratory). Laboratory provides two swabs for one animal – each swab can be used for sampling of different mucosae. Swabs will be analysed together like a mixed sample. If you like test the swabs separately, we will charge you two analysis – it is necesary to ask for separately testing!

FIV transmission

Threat of secondary infections

Worldwide spread

Clinical progression of the disease

Therapy

Prevention

Prognosis

Feline Immunodeficiency Virus (FIV) was first isolated in cats in California in 1986. FIV is a representative of lentiviruses belonging to the retrovirus family, which affects CD4' lymphocytes of the immune system of cats (and other representatives of the family Felidae) and induces slow, but serious immunodeficiency of the organism. The composition of the virus corresponds to the group of immunosuppressive lentiviruses, such as human HIV or SIV in monkeys.
FIV-virus, like other retroviruses, inserts its genetic code into the genome of the host cell by help of reverse transcriptase. It has substantial affinity to the cells of immune system. It replicates in macrophages and lymphocytes, and that not only in the auxiliary Th (CD4+) lymphocytes, but also in Tc and B-lymphocytes contrary to human HIV.

FIV transmission
The virus is present in blood, plasma, serum, cerebrospinal fluid and saliva. The concentration of the virus in saliva is high in patients with inflammation of the mucosa of the mouth. In external environment, FIV shows relative low stability and for transmission of infection a close contact between cats is necessary. Unlike FeLV, FIV does not cross the mucous barrier, and therefore the infection can be transmitted only through bite wounds or other contact of saliva of the infected animal with the blood of the healthy animal. On rare occasions, infection can be transmitted transplacentally or through the mother's milk. The highest prevalence of the infection is in cats of 6 to 10 years of age. Once the animal is infected, the infection stays for lifetime.

Threat of secondary infections
The virus causes immunosuppression (reduced ability of the cat to protect itself against other infections) and due to it the infected cats are highly susceptible to infections that do not usually affect healthy animals. These so-called secondary infections (bacterial infections of upper and lower respiratory tract, bacterial infection of urinary tract and skin infections) are the largest threat to FIV-positive cats. The following diseases are connected with the FIV-infection: immunodeficiency („feline AIDS", 15-20 % of infected cats), lymphopenia and neutropenia, anaemia and lymphoproliferative or myeloproliferative diseases.

Worldwide spread
FIV is present in cat population all over the world. FIV-positive cats were identified in the USA and Canada, Asia, Europe, Australia and Africa. The FIV-prevalence is approximately half the prevalence of FeLV. It is supposed to be from 2 % in Germany and the Netherlands to 30 % in Great Britain. In the USA, 1-16 % and in Japan up to 45% of cats are infected with FIV. The percentage of sick cats in the individual countries depends on the geographic conditions, in particular on breeding habits.
In the Czech Republic, the prevalence of FIV in cats is 5.8 %. These FIV-infected cats are mainly non-neutered tom cats (47.6 %) which can move freely outside. One percentage of cats tested in the Czech Republic was positive for both FIV and FeLV infections.

Clinical progression of the disease
The progression of FIV-infection can be divided into five clinical stages:
1. Acute infection.
2. Asymptomatic virus carrier.
3. Persistent generalized lymphadenopathy.
4. Complex of health problems similar to AIDS in humans.
5. Terminal stage characterized by development of pathological processes subject to complete collapse of natural immunity.

1. Acute infection
Occurs several weeks after getting infected and lasts 4 to 16 weeks. In this phase, consequent symptomatic therapy is sufficient. If the course of the disease is more serious, depressions and diarrhoeas can be observed and fever is often present. The onset of more serious health problems depends on a number of external factors, in particular on the presence of infectious agents (bacteria, fungi, parasites) and zoo-hygienic conditions of breeding. The death is caused by severe sepsis.

2. Asymptomatic virus carrier
This stage may last several months to years. After fall of temperature, relief of leukopenia and lymphadenopathy, the cats appear to be entirely healthy. Progressive development of secondary and opportunistic infections can be observed.

3. Persistent generalized lymphadenopathy (PGL)
The stage corresponds to the similar stage in HIV-infected patients. In practice, almost half of FIV-patients are brought to the veterinarian just in this stage. The cat owners notice only inappetence and loss of weight. If there are no distinctive clinical signs of secondary and opportunistic infections, the possible connection of the health problems with FIV-infection may be not taken into consideration. Proper clinical examination reveals feverish condition, leukopenia, lymphadenopathy and anaemia and acute necrotizing gingivitis in the mouth (gum tissue inflammation) and stomatitis (inflammation of mucosa in the mouth).

4. AIDS-related complex (ARC)

This stage is characterized by manifestation of chronic secondary and opportunistic infections (itch, bacterial infection of upper and lower respiratory tracts, demodicosis, loxoplazmosis, cryptococcosis, pock virus, systemic candidiasis, and bacterial infection of urinary tract). Bacterial infections affect gum tissue and the infections of upper and lower respiratory tract are manifested as chronic bronchitis, bronchiolitis, pneumonia, rhinitis and conjunctivitis. The weight of patients reduces by almost 20%. Approximately one third of patients shows advanced changes in blood count (anaemia, leukopenia, neutropenia, lymphopenia), lymphadenopathy. Cats remain in this stage for 6 months up to 5 years.

5. Terminal stage
The terminal stage lasts usually not more than 6 to 12 months. Loss of weight, anaemia and leukopenia are the most dominant signs and infections affect multiple organs in the body. The affection of the cerebral cortex of the cerebrum finds expression in dementia, psychosis, twitching of cheek muscles (buccinator muscles) and compulsive twitching of tongue. Nystagmus (eye twitching), ataxia and tremor are less frequent. In connection with secondary virus diseases and bacterial infections, glaucoma, uveitis (iris inflammation) and chronic conjunctivitis can be observed in the eyes of FIV-infected patients. As regards the skin diseases, the parasitosis, the mycotic and bacterial dermatitis are prevalent. The gastro-intestinal tract is prevalently affected by chronic diarrhoea. By endoscopic examination, destructive changes in the mucosa of small intestine can be discovered that look like parvovirus diseases. These are in particular mucosa denudation, loss of brush border (taenia), reduction of villi and dilatation of crypts. In the colon area, ulceration, pyogranulomatous inflammation nidi with infiltration of submucous layer by neutrofiles, macrophages and histiocytes occur prevalently. This stage ends by euthanasia or death of the animal.

Therapy
Non-specific therapy is focused on limitation of opprotunistic infections and supporting the entire health condition, i.e. introduction of infusion therapy, administration of wide-spectrum antibiotics and antiparasitics. The success depends to a great extent on the degree of damage to immune system and can be expected in particular in the first stages of the disease. Considered are preparations with immune-stimulating and antitumour activities. A close collaboration of the animal owner with the veterinarian and regular examination of the health condition of the patient, incl. repeated laboratory tests are precondition of the therapy.

Prevention
Prevention consists in comprehensive utilization of breeding possibilities. The principle of separation of FIV-positive animal should be pointed out to prevent the infection from spreading in the population. Thanks to the optimisation of the care and breeding conditions, FIV-positive cats can live several years without apparent health problems. Such measures include stress limitation, full nutrition and regular dehelmintisation. With regard to frequent inflammation of mouth in FIV-positive animals, regular removal of plaque is suitable. All health problems have to be consulted with and immediately treated by a veterinarian. If surgical treatment is indicated, the veterinary personnel are to be informed about the FIV-infection in the patient so that optimum postoperative care and separation of the patient in the hospital can be ensured. Separation in the household enables timely identification of health condition deterioration. In patient with suppressed immune response, this measure reduced the hazard of other infections. In no case, FIV-infected cats should get vaccines that contain live virus.

Prognosis
In patients with chronic health complications and positive test on FIV-presence the long-time prognosis is unfavourable. If the disease is diagnosed in early stage, the infected cat can live for several years. Patients which are asymptomic FIV-carriers are to be subjected to regular checks of health condition, connected with a parasitological test. In the terminal stage, the life expectation is very low (maximum 6 months). The life prognosis for kittens with combined FIV/FeLV, FIV/FIP or FIV/FPV infections is very poor.

The cats should be tested for FeLV and FIV every time they are ill, irrelevant of their age, negative results of previous tests and vaccination status.

References:
PEDERSEN, N.C et al. Isolation of a T-lymphotropic virus from domestic cats with an immunodeficiency-like syndrome. Science, v.235, p.790-793, 1987.
BENDINELLI et al. Feline immunodeficiency virus: an interesting model for AIDS studies and an important cat pathogen. Clin Microbiol Rev, v.8, p.87-112, 1995.
HARTMANN, K. Feline Immunodeficiency virus infection: an overview. Vet J, v.155, p.123-127, 1998.
Levy J. at all. Feline Retrovirus testing and management. Comp Cont Edu 2001;23(7):652-657.
Nemoci psa a kočky II. Díl, Prof. MVDr. Miroslav SVOBODA, CSc. Prof. David F. SENIOR, D.V.M., BVSc, dipl. ACVIM, dipl. ECVIM-CA Doc. MVDr. Jaroslav DOUBEK, CSc. MVDr. Jiří KLIMEŠ, Csc.; Česká asociace veterinárních lékařů malých zvířat (ČAVLMZ); Noviko, a. s. Brno 2001