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How should environmental stress affect the population dynamics of disease?
Author(s) -
Lafferty Kevin D.,
Holt Robert D.
Publication year - 2003
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1046/j.1461-0248.2003.00480.x
Subject(s) - disease , fecundity , population , stress (linguistics) , biology , ecology , environmental stress , susceptible individual , survivorship curve , affect (linguistics) , transmission (telecommunications) , demography , environmental health , medicine , psychology , linguistics , philosophy , communication , sociology , electrical engineering , engineering
We modelled how stress affects the population dynamics of infectious disease. We were specifically concerned with stress that increased susceptibility of uninfected hosts when exposed to infection. If such stresses also reduced resources, fecundity and/or survivorship, there was a reduction in the host carrying capacity. This lowered the contact between infected and uninfected hosts, thereby decreasing transmission. In addition, stress that increased parasite mortality decreased disease. The opposing effects of stress on disease dynamics made it difficult to predict the response of disease to environmental stress. We found analytical solutions with negative, positive, convex and concave associations between disease and stress. Numerical simulations with randomly generated parameter values suggested that the impact of host‐specific diseases generally declined with stress while the impact of non‐specific (or open) diseases increased with stress. These results help clarify predictions about the interaction between environmental stress and disease in natural populations.