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

The increasing awareness of the ecological impact of domestic cats (Felis c atus) as wildlife predators has given rise to much effort in research on ca t control, but studies related to the spread of pathogens in natural popula tions remain almost non-existent. We aimed to determine the infection strat egy 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 studie d an urban population of stray cats over three years, monitoring its epidem iology and its social and spatial structures. Despite a high cat density, b oth transmission rate and prevalence of FIV were relatively low. Socially d ominant males were more likely to be infected. In addition, males of the st udy 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-r isk individuals whose social ranking allowed a high probability of retransm itting the virus.