Opposite outcomes of coinfection at individual and population scales

Erin E. Gorsich*, Rampal S. Etienne, Jan Medlock, Brianna R. Beechler, Johannie M. Spaan, Robert S. Spaan, Vanessa O. Ezenwa, Anna E. Jolles

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Coinfecting parasites and pathogens remain a leading challenge for global public health due to their consequences for individual-level infection risk and disease progression. However, a clear understanding of the population-level consequences of coinfection is lacking. Here, we constructed a model that includes three individual-level effects of coinfection: mortality, fecundity, and transmission. We used the model to investigate how these individual-level consequences of coinfection scale up to produce population-level infection patterns. To parameterize this model, we conducted a 4-y cohort study in African buffalo to estimate the individual-level effects of coinfection with two bacterial pathogens, bovine tuberculosis (bTB) and brucellosis, across a range of demographic and environmental contexts. At the individual level, our empirical results identified bTB as a risk factor for acquiring brucellosis, but we found no association between brucellosis and the risk of acquiring bTB. Both infections were associated with reductions in survival and neither infection was associated with reductions in fecundity. The model reproduced coinfection patterns in the data and predicted opposite impacts of coinfection at individual and population scales: Whereas bTB facilitated brucellosis infection at the individual level, our model predicted the presence of brucellosis to have a strong negative impact on bTB at the population level. In modeled populations where brucellosis was present, the endemic prevalence and basic reproduction number (R-0) of bTB were lower than in populations without brucellosis. Therefore, these results provide a data-driven example of competition between coinfecting pathogens that occurs when one pathogen facilitates secondary infections at the individual level.

Original languageEnglish
Pages (from-to)7545-7550
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number29
DOIs
Publication statusPublished - 17-Jul-2018

Keywords

  • African buffalo
  • brucellosis
  • tuberculosis
  • coinfection
  • competition
  • BUFFALO SYNCERUS-CAFFER
  • RANGING AFRICAN BUFFALO
  • DEPENDENT ENHANCEMENT
  • DISEASE INTERFERENCE
  • BOVINE TUBERCULOSIS
  • CROSS-IMMUNITY
  • BRUCELLOSIS
  • INFECTION
  • DYNAMICS
  • EPIDEMIOLOGY

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