FeLV is spread from cat-to-cat through bite wounds, salivary secretions, and casual contact with infected cats. In animals with persistent viremic infection, the saliva contains substantial quantities of the virus. Social grooming, the use of common litter boxes, and shared food and water bowls can also help transmission. Kittens can contract the disease from their mothers while still in the womb, or while nursing. Transfer of the virus to kittens in utero is often fatal. Transfusion of blood from an infected cat can also be a means for transmission. Iatrogneic transfer by fomites or the use of contaminated medical equipment (i.e. needles) as well as the potential for insect vector transmission through flea bites have been identified as potential sources of infection. FeLV is extremely labile; thus, exposure to virus persisting in the environment, on fomites, or in aerosolized secretions is not an efficient means of viral transmission.
AAFP, 2006; AVMA, 2004; Barr, 2007; Hartman, 2006; Hosie et al., 1993; Levy, 2000; Merial Canada, 2010; Sykes, 2010