A&M CVM Researcher Publishes in Nature Reviews Microbiology

Farm animals are more than a means of livelihood: They can serve as models for understanding how infectious diseases are transmitted in human populations.

This novel idea was presented in a paper published last month in the journal Nature Reviews Microbiology.

Dr. Renata Ivanek, assistant professor of epidemiology at the Texas A&M University College of Veterinary Medicine & Biomedical Sciences, was one of the contributing authors of the paper. (Other study participants, including main author Dr. Cristina Lanzas, Patrick Ayscue and Dr. Yrjo T. Grohn, were from Cornell University's College of Veterinary Medicine.)

According to the study, which was funded by the National Institutes of Health, understanding the complex processes that underlie the transmission of infectious diseases in human populations is critical for designing effective intervention strategies for these diseases. Mathematical models of infectious disease transmission have played a major role in understanding these processes.

"Mathematical models provide a platform where the various factors that influence the transmission of infectious diseases [for example, strain or dose of pathogen] can be tested in a cost-effective manner with minimal effort," said Ivanek. "Designing experiments to test these diverse factors would be very complicated."

Further, the predictions generated by these mathematical models can be used to forecast "the long-term epidemiological and economic consequences of intervention strategies," the authors state.

However, for these predictions to be considered accurate, the models have to be validated or verified against data acquired in the field.

"It is difficult to validate theoretical predictions of infectious disease transmission in human populations because there is very little empirical data in this regard," Ivanek explained. "But farm animals can help fill this gap."

The authors offer several reasons for why farm animal populations can serve as a good model for disease transmission in human populations. These include similarities between farm animal and human populations with regard to disease mechanisms, immune systems and factors that contribute to disease outbreak (for example, crowding, close contact and poor hygiene).

The study also provides examples of how farm animal models have been used in infectious disease research. The authors discuss how Marek's disease in poultry has been used to study factors that cause pathogens to become increasingly virulent in vaccinated populations and how swine populations harboring influenza viruses have been used to study how these viruses emerge and are transmitted across species.

Further, Ivanek explained that empirical data for one of her current projects, funded by a $1.4 million National Science Foundation grant, will be obtained from a farm animal model. The project, which addresses the transmission mechanism of infectious diseases caused by pathogens that are intermittently shed and persist in the environment, will use E. coli transmission among cattle as a model system.

"We will use empirical data from this system to validate the predictions of theoretical models, which will be generated simultaneously," said Ivanek.

Ivanek's project underlines one of the main points of the review: the importance of combining mathematical and empirical approaches to investigating disease.

The review findings suggest that investigating the dynamics of disease transmission within the herd environment is a "one-health" approach (that is, addressing both animal and human health) for developing novel treatments and better diagnostic and predictive tools for infectious diseases.

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