Transmission of Feline Immunodeficiency Virus in a population of cats (Felis catus)

The increasing awareness of the ecological impact of domestic cats (Felis catus) as wildlife predators has given rise to much effort in research on cat control, but studies related to the spread of pathogens in natural populations remain almost non-existent. We aimed to determine the infection strategy of Feline Immunodeficiency Virus (FIV) in a natural population of cats, focusing on qualitative and quantitative aspects of its transmission. FIV is a lethal retrovirus infecting cats world-wide, transmitted by bites. It has an interesting potential as a control agent for this species. We studied an urban population of stray cats over three years, monitoring its epidemiology and its social and spatial structures. Despite a high cat density, both transmission rate and prevalence of FIV were relatively low. Socially dominant males were more likely to be infected. In addition, males of the study population were less often infected than in another population, where a polygynous mating system involved more fights. Infected individuals lived long enough to acquire the virus and infect another cat. Because they were subordinates, non-infected cats had a shorter life expectancy, which would not have permitted the spread of FIV. Thus, FIV infected predominantly at-risk individuals whose social ranking allowed a high probability of retransmitting the virus.