Sustaining Transmission in Different Host Species: The Emblematic Case of Sarcoptes scabiei ; Bioscience

Abstract

Some pathogens sustain transmission in multiple different host species, but how this epidemiologically important feat is achieved remains enigmatic. Sarcoptes scabiei is among the most host generalist and successful of mammalian parasites. We synthesize pathogen and host traits that mediate sustained transmission and present cases illustrating three transmission mechanisms (direct, indirect, and combined). The pathogen traits that explain the success of S. scabiei include immune response modulation, on-host movement capacity, off-host seeking behaviors, and environmental persistence. Sociality and host density appear to be key for hosts in which direct transmission dominates, whereas in solitary hosts, the use of shared environments is important for indirect transmission. In social den-using species, combined direct and indirect transmission appears likely. Empirical research rarely considers the mechanisms enabling S. scabiei to become endemic in host species-more often focusing on outbreaks. Our review may illuminate parasites' adaptation strategies to sustain transmission through varied mechanisms across host species. ; Australian Research CouncilAustralian Research Council [LP180101251]; Tasmanian Government Honours Scholarship in Wildlife Conservation by Department of Primary Industries, Parks, Water, and Environment ; Published version ; We thank Chris Burridge and Geoff While for feedback and assessment of an early draft. This work was supported by an Australian Research Council Link Project grant (no. LP180101251) to SC and the Tasmanian Government Honours Scholarship in Wildlife Conservation awarded to EB by the Department of Primary Industries, Parks, Water, and Environment. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US government. ; Public domain authored by a U.S. government employee