TY - JOUR
T1 - Costs and benefits of group living with disease
T2 - A case study of pneumonia in bighorn lambs (Ovis canadensis)
AU - Manlove, Kezia R.
AU - Frances Cassirer, E.
AU - Cross, Paul C.
AU - Plowright, Raina K.
AU - Hudson, Peter J.
N1 - Publisher Copyright:
© 2014 The Author(s) Published by the Royal Society. All rights reserved.
PY - 2014/11/5
Y1 - 2014/11/5
N2 - Group living facilitates pathogen transmission among social hosts, yet temporally stable host social organizations can actually limit transmission of some pathogens. When there are few between-subpopulation contacts for the duration of a disease event, transmission becomes localized to subpopulations. The number of per capita infectious contacts approaches the subpopulation size as pathogen infectiousness increases. Here, we illustrate that this is the case during epidemics of highly infectious pneumonia in bighorn lambs (Ovis canadensis). Weclassified individually marked bighorn ewes into disjoint seasonal subpopulations, and decomposed the variance in lamb survival toweaning into components associated with individual ewes, subpopulations, populations and years. During epidemics, lamb survival varied substantially more between ewe-subpopulations than across populations or years, suggesting localized pathogen transmission. This pattern of lamb survival was not observed during years when disease was absent. Additionally, group sizes in ewe-subpopulations were independent of population size, but the number of ewe-subpopulations increased with population size. Consequently, although one might reasonably assume that force of infection for this highly communicable disease scales with population size, in fact, host social behaviour modulates transmission such that disease is frequency-dependent within populations, and some groups remain protected during epidemic events.
AB - Group living facilitates pathogen transmission among social hosts, yet temporally stable host social organizations can actually limit transmission of some pathogens. When there are few between-subpopulation contacts for the duration of a disease event, transmission becomes localized to subpopulations. The number of per capita infectious contacts approaches the subpopulation size as pathogen infectiousness increases. Here, we illustrate that this is the case during epidemics of highly infectious pneumonia in bighorn lambs (Ovis canadensis). Weclassified individually marked bighorn ewes into disjoint seasonal subpopulations, and decomposed the variance in lamb survival toweaning into components associated with individual ewes, subpopulations, populations and years. During epidemics, lamb survival varied substantially more between ewe-subpopulations than across populations or years, suggesting localized pathogen transmission. This pattern of lamb survival was not observed during years when disease was absent. Additionally, group sizes in ewe-subpopulations were independent of population size, but the number of ewe-subpopulations increased with population size. Consequently, although one might reasonably assume that force of infection for this highly communicable disease scales with population size, in fact, host social behaviour modulates transmission such that disease is frequency-dependent within populations, and some groups remain protected during epidemic events.
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U2 - 10.1098/rspb.2014.2331
DO - 10.1098/rspb.2014.2331
M3 - Article
C2 - 25377464
AN - SCOPUS:84908690004
SN - 0962-8452
VL - 281
JO - Proceedings of the Royal Society B: Biological Sciences
JF - Proceedings of the Royal Society B: Biological Sciences
IS - 1797
M1 - 20142331
ER -