, Volume 3, Issue 2, pp 95-102

First online:

Dynamics of Mycoplasmal Conjunctivitis in the Native and Introduced Range of the Host

  • André A. DhondtAffiliated withLaboratory of Ornithology, Cornell University Email author 
  • , Alexander V. BadyaevAffiliated withEcology and Evolutionary Biology, University of Arizona
  • , Andrew P. DobsonAffiliated withEcology and Evolutionary Biology, Princeton University
  • , Dana M. HawleyAffiliated withLaboratory of Ornithology, Cornell UniversityEcology and Evolutionary Biology, Cornell University
  • , Melanie J.L. DriscollAffiliated withLaboratory of Ornithology, Cornell University
  • , Wesley M. HochachkaAffiliated withLaboratory of Ornithology, Cornell University
  • , David H. LeyAffiliated withCollege of Veterinary Medicine, North Carolina State University

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In 1994, Mycoplasma gallisepticum, a common bacterial poultry pathogen, caused an epidemic in house finches in the eastern part of their North American range where the species had been introduced in the 1940s. Birds with mycoplasmal conjunctivitis were reported across the entire eastern United States within 3–4 years. Here we track the course of the Mycoplasma gallisepticum epidemic as it reached native, western North American populations of the house finch. In 2002, Mycoplasma gallisepticum was first observed in a native house finch population in Missoula, MT, where it gradually increased in prevalence during the next 2 years. Concurrently, house finches with conjunctivitis were reported with increasing number in the Pacific Northwest. In native populations of the host, the epidemic expanded more slowly, and reached lower levels of prevalence than in the eastern, introduced range of the species. Maximal prevalence was about half in the Missoula population than in local populations in the East. Although many factors can contribute to these differences, we argue that it is most likely the higher genetic heterogeneity in western than in eastern populations caused the lower impact of the pathogen.


Mycoplasma gallisepticum Carpodacus mexicanus house finch genetic bottleneck epidemic House Finch Disease Survey