title: Sapronosis: a distinctive type of infectious agent.
abstract: Sapronotic disease agents have evolutionary and epidemiological properties unlike other infectious organisms. Their essential saprophagic existence prevents coevolution, and no host-parasite virulence trade-off can evolve. However, the host may evolve defenses. Models of pathogens show that sapronoses, lacking a threshold of transmission, cannot regulate host populations, although they can reduce host abundance and even extirpate their hosts. Immunocompromised hosts are relatively susceptible to sapronoses. Some particularly important sapronoses, such as cholera and anthrax, can sustain an epidemic in a host population. However, these microbes ultimately persist as saprophages. One-third of human infectious disease agents are sapronotic, including nearly all fungal diseases. Recognition that an infectious disease is sapronotic illuminates a need for effective environmental control strategies.
authors.affiliation: Department of Ecology, Evolution, and Marine Biology and Marine Science Institute, University of California, Santa Barbara, CA 93106, USA. Electronic address: Kuris@lifesci.ucsb.edu.
authors.forename: Armand M
authors.initials: AM
authors.lastname: Kuris
authors.affiliation: Western Ecological Research Center, US Geological Survey c/o Marine Science Institute, University of California, Santa Barbara, CA 93106, USA.
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Lafferty
authors.affiliation: Marine Science Institute, University of California, Santa Barbara, CA 93106, USA; Hopkins Marine Station, Stanford University, Pacific Grove, CA, 93950, USA.
authors.forename: Susanne H
authors.initials: SH
authors.lastname: Sokolow
mesh_terms: D000818:Animals; D044822:Biodiversity; D054884:Host-Pathogen Interactions; D006801:Humans; D007239:Infections / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology / Q000469:parasitology / Q000635:transmission; D008954:Models, Biological
keywords: Allee effect; Legionnaire's disease; Naegleria; reservoir; sapronosis; zoonosis