Foamy Virus (Spumavirus) Infection
All primate species have been shown to be frequent hosts to non-pathogenic retroviruses called Foamy viruses (SFV), which appear to be almost commensal organisms, causing no known pathology in the infected individuals. Lineage-specific spumaviruses have been found in all primate species studied, and the phylogeny of these viruses mirrors the phylogeny of the primate species themselves. While infection rates >20% have been documented in wild chimpanzees, SFV infections in humans seems to be absent, with the exception of individuals who regularly contact great apes or other primate species (zoo keepers or hunters). Especially given the evidence that humans can be asymptomatically infected and become long-term carriers of SFV, is no explanation for this lack of endemic infection in humans. Indeed, as the common ancestor of humans and chimpanzees very likely harbored the virus, the question arises as to how endemic SFV was eliminated from the human population.