Simple Summary Feline leukemia virus (FeLV) is spread through domestic cats ( Felis catus ) and has been associated with a wide spectrum of diseases, mainly leukemia and lymphoma. FeLV is highly prevalent in Brazil and other South American countries. The survival rate of cats persistently infected with FeLV is low, and many animals die within three years of infection. The present study aimed to investigate the epidemiology of this virus and related diseases in an urban cat population from Brazil. It was carried out with a total of 366 domestic cats in veterinary facilities from Caxias do Sul, a city in South Brazil. The results demonstrate that 109 (around 30%) cats were infected with FeLV and presented different disease outcomes (highlighting progressive and regressive outcomes). The main risk factors for cats becoming infected were the lack of a specific vaccination against FeLV and outdoor access. FeLV infection was also associated with apathetic behavior, lymphoma, and anemia. The present study provides important epidemiological insights into the FeLV domestic cat infections in Brazil, highlighting the high prevalence of the disease and its concerning clinical outcomes as well as the benefits of vaccination for the health of cats. Abstract Feline leukemia virus (FeLV) is a retrovirus distributed worldwide in domestic cats and with different outcomes (progressive, regressive, abortive, focal). The present study reports an epidemiological survey of FeLV frequency and the evaluation of some risk factors and the two main disease outcomes (progressive and regressive) in an urban cat population from Brazil. A total of 366 cats with sociodemographic information and p27 FeLV antigen test performed were included in the study. FeLV DNA (provirus) in the blood samples of all cats was detected via real-time polymerase chain reaction (qPCR). Plasma samples from 109 FeLV-positive and FeLV-negative cats were also submitted to reverse transcription (RT-qPCR) to determine the FeLV viral load. The results demonstrated that 112 (30.6%) cats were positive through the p27 antigen and/or qPCR. A risk factor analysis demonstrated that cats without vaccination against FeLV (OR 9.9, p < 0.001), clinically ill (OR 2.9, p < 0.001), with outdoors access (OR 2.7, p < 0.001), and exhibiting apathetic behavior (OR 3.1, p < 0.001) were more likely to be infected with FeLV. FeLV-infected cats were also more likely to present with anemia (OR 13, p < 0.001) and lymphoma (OR 13.7, p = 0.001). A comparative analysis of the different detection methods in a subset of 109 animals confirmed FeLV infection in 58 cats, including 38 (65.5%) with progressive, 16 (27.6%) with regressive, and 4 (6.9%) with probably focal outcome diseases. In conclusion, this study demonstrates a high prevalence of FeLV in this urban cat population from Brazil and highlights the need to establish more effective prevention strategies (such as viral testing, vaccination programs, specific care for FeLV-positive cats) to reduce diseases associated with this virus in Brazil.
【저자키워드】 Brazil, Prevalence, PCR, Viral load, FeLV, proviral load,