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Seroprevalences of FeLV and FIV in cats in North America

Burling AN, Levy JK, Scott HM, et al. Seroprevalences of feline leukemia virus and feline immunodeficiency virus infection in cats in the United States and Canada and risk factors for seropositivity. J Am Vet Med Assoc. 2017 Jul 15; 251(2): 187-194.

Because feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) affect cats worldwide, the veterinary community has periodically performed cross-sectional seroprevalence surveys for both viruses.  In 2006, a survey of 18,038 cats in the United States and Canada reported that 2.3% of cats were seropositive for FeLV antigen and 2.5% of cats were seropositive for antibodies against FIV. Another survey in 2009 in Canada of 11,144 cats reported seroprevalences of 3.4% for FeLV antigen and 4.3% for anti-FIV antibody. In both studies, risk factors for seropositivity were identified as sexually intact male cats, adult cats, outdoor access, and unhealthy condition. Also, cats tested in veterinary clinics were more likely to have a positive test result than cats tested in shelters.

The current study included 62,201 cats tested at veterinary clinics (n=45,406) and shelters (16,895). The results demonstrated an overall seroprevalence of 3.1% for FeLV antigen and 3.6% for anti-FIV antibody. The risk factors for both viruses were adult age, outdoor access, clinical disease and being a sexually intact male cat. Again, seropositivity for each virus was higher for cats tested in clinics than those tested in shelters.

The breakdown on seropositivity in cats with different disease conditions is:

  •  Oral disease (1,611 cats) – FeLV+ (76 or 4.7%); FIV+ (157 or 9.7%)
  • Respiratory disease (4,835 cats) – FeLV+ (385 or 8.0%); FIV+ (308 or 6.4%)
  • Abscesses or bite wounds (1,983 cats) – FeLV+ (110 or 5.5%); FIV+ (247 or 12.5%)

Unhealthy cats seropositive for either or both viruses: 2,368 of 17,041 (13.9%)

Healthy cats seropositive for either for both viruses: 1,621 of 45,260 (3.6%)

Feral cats had significantly higher seroprevalence: 113 of 2020 (5.6%) for FeLV and 234 of 2020 for FIV (11.6%) than other types of unowned cats

Comparing geographical regions, cats with seropositivity for FeLV were significantly higher only in the Midwest compared to Canada. In the cats with FIV seropositivity, all regions of the United States had significantly higher odds than Canada with the South and West having even slightly higher proportions.

The authors note in this present study, the seroprevalence of these two important infectious diseases, FeLV and FIV, have not declined in North America over the past decade. The study also showed that despite known risks of infection in cats that fight, compliance with testing recommendation between veterinarians and cat owners remains low. Despite the American Association of Feline Practitioners’ guidelines recommending retesting – only 54% of veterinarians recommended follow up tests and only 13% of cats were eventually retested.

In conclusion, the recommendation based on the study’s results is for veterinarians and shelter managers to improve compliance with existing guidelines for management of FeLV and FIV. The guidelines include recommendations for testing of all owned cats, retesting of cats that develop disease or may be been exposed to infected cats, vaccination against FeLV for all kittens and cats at risk for exposure, segregation of infected cats, and neutering of unowned free-roaming cats. (VT)

See also:
Goldcamp CE, Levy JK, Edinboro CH, Lachtara JL. Seroprevalences of feline leukemia virus and feline immunodeficiency virus in cats with abscesses or bite wounds and rate of veterinarian compliance with current guidelines for retrovirus testing. J Am Vet Med Assoc. 2008 Apr 15; 232(8): 1152-1158.