Closing the gap on causal processes of infection risk from cross-sectional data: structural equation models to understand infection and co-infection

Scott Carver*, Julia A. Beatty, Ryan M. Troyer, Rachel Harris, Kathryn Stutzman-Rodriguez, Vanessa R. Barrs, Cathy Chan, Severine Tasker, Michael R. Lappin, Sue VandeWoude

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

13 Citations (Scopus)
329 Downloads (Pure)

Abstract

Background: Epidemiological studies of disease exposure risk are frequently based on observational, cross-sectional data, and use statistical approaches as crucial tools for formalising causal processes and making predictions of exposure risks. However, an acknowledged limitation of traditional models is that the inferred relationships are correlational, cannot easily distinguish direct from indirect determinants of disease risk, and are often considerable simplifications of complex interrelationships. This may be particularly important when attempting to infer causality in patterns of co-infection through pathogen-facilitation.

Methods: We describe analyses of cross-sectional data using structural equation models (SEMs), a contemporary advancement on traditional regression approaches, based on our study system of feline gammaherpesvirus (FcaGHV1) in domestic cats.

Results: SEMs strongly supported a latent (host phenotype) variable associated with FcaGHV1 exposure and co-infection risk, suggesting these individuals are simply more likely to become infected with multiple pathogens. However, indications of pathogen-covariance (potential facilitation) were also variably detected: potentially among FcaGHV1, Bartonella spp, and Mycoplasma spp.

Conclusions: Our models suggest multiple exposures are primarily driven by host phenotypic traits, such as aggressive male phenotypes, and secondarily by pathogen-pathogen interactions. The results of this study demonstrate the application of SEMs to understanding epidemiological processes using observational data, and could be used more widely as a complementary tool to understand complex cross-sectional information in a wide variety of disciplines.
Original languageEnglish
Article number658
Number of pages20
JournalParasites and Vectors
Volume8
Issue number1
DOIs
Publication statusPublished - 23 Dec 2015

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