Critical thresholds in sea lice epidemics: evidence, sensitivity and subcritical estimation.
Summary of "Critical thresholds in sea lice epidemics: evidence, sensitivity and subcritical estimation."
Host density thresholds are a fundamental component of the population dynamics of pathogens, but empirical evidence and estimates are lacking. We studied host density thresholds in the dynamics of ectoparasitic sea lice (Lepeophtheirus salmonis) on salmon farms. Empirical examples include a 1994 epidemic in Atlantic Canada and a 2001 epidemic in Pacific Canada. A mathematical model suggests dynamics of lice are governed by a stable endemic equilibrium until the critical host density threshold drops owing to environmental change, or is exceeded by stocking, causing epidemics that require rapid harvest or treatment. Sensitivity analysis of the critical threshold suggests variation in dependence on biotic parameters and high sensitivity to temperature and salinity. We provide a method for estimating the critical threshold from parasite abundances at subcritical host densities and estimate the critical threshold and transmission coefficient for the two epidemics. Host density thresholds may be a fundamental component of disease dynamics in coastal seas where salmon farming occurs.
Affiliation
Department of Geology and Geophysics, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa, Honolulu, HI 96822, USA. neil@soest.hawaii.edu
Journal Details
This article was published in the following journal.
Name: Proceedings. Biological sciences / The Royal Society
ISSN: 1471-2954
Pages: 1950-8
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/22217721
- DOI: http://dx.doi.org/10.1098/rspb.2011.2210
Medical and Biotech [MESH] Definitions
Lice
A general name for small, wingless, parasitic insects, previously of the order Phthiraptera. Though exact taxonomy is still controversial, they can be grouped in the orders ANOPLURA (sucking lice), MALLOPHAGA (biting lice), and Rhynchophthirina (elephant-lice).
Audiometry
The testing of the acuity of the sense of hearing to determine the thresholds of the lowest intensity levels at which an individual can hear a set of tones. The frequencies between 125 and 8000 Hz are used to test air conduction thresholds and the frequencies between 250 and 4000 Hz are used to test bone conduction thresholds.
Phthiraptera
An order of small, wingless parasitic insects, commonly known as lice. The suborders include ANOPLURA (sucking lice); AMBLYCERA; ISCHNOCERA; and Rhynchophthirina (elephant and warthog lice).
Mallophaga
An order of insects comprising the chewing lice or biting lice, many of which are parasitic on wild birds and domestic fowl and on wild and domestic mammals. Suborders include Amblycera and Ischnocera.
Epidemics
Sudden outbreaks of a disease in a country or region not previously recognized in that area, or a rapid increase in the number of new cases of a previous existing endemic disease. Epidemics can also refer to outbreaks of disease in animal or plant populations.
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