Feline immunodeficiency virus (FIV): Prevalence, risk factors, and clinical findings in domestic cats (Felis catus) from southern Brazil

Abstract

Feline immunodeficiency virus (FIV) is a retrovirus affecting domestic cats worldwide and causing immunosuppression and reduced quality of life. The prevalence of FIV infection varies according to geographic regions / countries and it is associated with domestic cat health managements (vaccination, neutering, basic health care, etc.). This study aimed to evaluate prevalence, risk factors and some clinical information of FIV infection in a domestic cat population in southern Brazil. A total of 366 cats from ten different veterinary facilities and 43 neighborhoods located in the city of Caxias do Sul were sampled for this study. Each animal was examined by a clinical veterinarian and blood was collected for laboratory analysis. Blood samples were tested with a point-of-care (POC) assay to detect FIV antibodies and a real-time polymerase chain reaction (qPCR) to detect and quantify FIV proviral DNA. The results demonstrated an overall prevalence of 7.1 % (n = 26; 95 % CI = 4.9 % - 10.2 %) of FIV infection. FIV-positive cats demonstrated undetectable (n = 6; 23.1 %) and detectable (n = 20; 76.9 %) proviral DNA, with loads varying from less than 10 (10¹) to 4460,000 (10^6.6) with a mean of 480,000 (10^5.7) copies/mL. FIV-positive cats were significantly older (median age of 7 years), also presenting outdoor access (OR: 5.0, p = 0.046), feline leukemia virus (FeLV) coinfection (OR: 7.1, p < 0.001) and other chronic diseases (OR: 4.1, p = 0.34) as main risk factors. FIV-positive animals presented a 9.9- and 7.6-times higher risk for developing lymphoma and anemia in the multivariate analysis. This study contributes to assess some important epidemiological aspects of FIV infection in cats in southern Brazil, highlighting the strong association of FIV and FeLV coinfection.

Keywords: Clinical findings, PCR; FIV; Feline diseases; Retrovirus; Viral load.