New tool assesses costs and benefits of managing evolving pathogens and pests


UNIVERSITY PARK, PA – Spending money now on antibiotic stewardship practices or saving money but running the risk of potentially deadly antibiotic-resistant bacteria emerging? A new economic tool can help physicians, farmers and others whose activities may influence the evolution of biological organisms, such as pathogens and insects, decide when to invest in management strategies. evolution.

The model, developed by an international team of scientists and published today (November 16) in the journal PLOS Biology, suggests that management of evolution is beneficial if increasing the shelf life of the product – for example, an antibiotic or an antiparasitic crop – which results from management is greater than the increase in profit which could be obtained presently by not managing evolution.

“The bottom line is that there is a simple relationship defining when it is worth investing in scalable management. And it turns out the breakeven point is surprisingly small, ”said Andrew Read, Evan Pugh professor of biology and entomology and director of the Huck Institutes of the Life Sciences, Penn State. “Management doesn’t have to be that efficient and it’s worth it. We encourage people to implement practices now that will not only protect their products and long-term benefits, but also help protect human health and well-being. “

According to researchers, human behavior often drives the evolution of biological organisms in ways that can have a profound negative impact on human well-being. For example, by using crops genetically modified to produce toxins from the fungus Bacillus thuringiensis (Bt) as a pest deterrent, farmers may unintentionally increase the number of insects resistant to the toxin, thus making the use of Bt as a pest deterrent. an ineffective pest control strategy. In another example, the overuse of antibiotics in hospitals can lead to the overgrowth of resistant bacteria, which can hamper our ability to treat infections.

Read explained that several evolution management strategies already exist. With Bt crops, farmers can set aside areas to grow non-Bt crops so that Bt-sensitive insects have a refuge to reproduce. This strategy, he said, has proven to more than double the lifespan of Bt crops before Bt-resistant insects take over. Likewise, implementing antibiotic management policies in hospitals, such as using antibiotics only when needed and optimizing the dose and duration of treatment, can lengthen the lifespan. life-saving antibiotics.

“The problem is, people often forsake evolution management because of the upfront costs of investing in it,” Read said. “But our new model shows that in most cases the benefits of managing evolution outweigh the costs. “

The centerpiece of the team’s new analysis, said senior author Troy Day, professor of mathematics and statistics at Queens University, is a mathematical formula that determines when doctors, farmers and other “managers of evolution ”will have sufficient incentives to manage the living resources under their control, trading the short-term costs of stewardship for the long-term benefits of delaying adverse development.

“For example,” added David Kennedy, assistant professor of biology, Penn State, “when a patient arrives at an emergency care facility, screening to determine if he is colonized with a dangerous” superbug. ” [or antibiotic-resistant bacterium] is expensive, but protects future patients by isolating superbug carriers from others.

In addition to projecting the course of evolution of biological organisms under different scenarios, as well as the profits of businesses or owners, the model also examines the effectiveness of potential policies that could encourage the management of evolution, such as tax strategies or government subsidies. To do this, the researchers incorporated game theory – an economic tool for analyzing how the decisions of individuals can impact others, such as hospitals in the same region from which patients can become infected or corn farmers. with neighboring fields owned by other farmers. Their analysis of game theory identifies the conditions under which outcomes can be improved through policies that change incentives or facilitate coordination between individuals.

“In the example of antibiotic-resistant bacteria, hospitals could go above and beyond to control the spread of superbugs through methods such as community contact tracing,” said David McAdams, professor of business administration at the ‘Duke University. “It would incur additional costs and, on its own, a hospital would probably not have the incentive to do so. But if each hospital took this extra step, they could all collectively benefit from slowing the spread of these bacteria. Game theory gives you a systematic way to think about these possibilities and maximize overall well-being. “

The team concluded that managing evolution can be economically beneficial under a remarkably wide range of conditions.

Kennedy said, “Our research shows that taking action to manage change can go hand in hand with maximizing profits. “

The Science and Technology Branch, Department of Homeland Security, Fogarty International Center, National Institutes of Health, Natural Sciences and Engineering Research Council of Canada, and Institute of General Medical Sciences supported this research. .


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