Antimicrobial resistance is not only a major public health threat, but also an economic one, according to researchers at The World Bank. Their new study, published in the journal World Development, suggests that an increase in drug-resistant microbes could cause millions more people to fall into extreme poverty within the next few decades. “Nobody has estimated the poverty effects before,” says study author Karen Thierfelder, an economics professor at the U.S. Naval Academy and consultant for The World Bank. “We’d like to make more people aware of the problem.”

Due in large part to antibiotic overuse, pathogenic microbes are evolving resistance to existing treatments. More sick people means greater healthcare costs. But it could also mean a reduced labor supply as working age individuals succumb to previously treatable illnesses—and as sick days increase and productivity decreases. The livestock industry in particular could suffer as drugs used to treat animals become less effective and countries, fearing disease spread, limit livestock imports.

To better understand how these many consequences might affect global poverty levels, the researchers began by using a model, developed previously by Thierfelder and collaborators, that captures economic linkages within regions, such as the effect of agricultural output on the processed food industry, as well as trade between regions.

The team used the World Bank’s current economic growth projections through 2050 as a baseline to represent a world without antimicrobial resistance. The researchers then input the possible effects of antimicrobial resistance on the labor supply, labor productivity, healthcare costs, livestock production, and restrictions on livestock trade under lower-, middle-, and higher-antimicrobial resistance scenarios. They input the results into another model, developed by the World Bank, that simulates how global economic changes affect income distribution and poverty measures. The model might show, for example, how restrictions on global trade could increase the cost of food at a more local scale and, subsequently, increase a household’s expenses. It uses household surveys that cover employment, income, and consumption for 104 countries.

The team projected how antimicrobial resistance could have an impact on household finances by incorporating changes in prices and wages for skilled and unskilled workers that occur under each of the antimicrobial resistance scenarios. Compared to the baseline projection, the global economic output is projected to drop by 1.1% by 2050 under the lower antimicrobial resistance scenario and 3.8%, or 6.1 trillion US dollars, under the most severe scenario.

Low income countries have a higher incidence of infectious diseases and also a greater dependence on labor incomes. Consequently, under the higher antimicrobial resistance scenario, the model suggests economic output of low-income countries would fall by 5.6% compared to the baseline, while high-income countries would fall by 3.1%. The number of people experiencing extreme poverty in 2050 is projected to increase by 6.9 million under the least severe scenario and 28.3 million under the most severe scenario, with the vast majority living in low-income countries.

“Antibiotic resistance was framed as a biomedical problem for a long time,” says Didier Wernli, a senior researcher at the Global Studies Institute at the University of Geneva and visiting assistant professor at the School of Public Health at the University of Hong Kong. According to Wernli’s own work, researchers and policymakers have recently come to see these challenges “as a problem of security, and as a problem of development.” The World Bank study’s projections are an important contribution to this wider discussion, but much uncertainty remains regarding the implications for poverty and development, Wernli notes.

Acknowledging the uncertainties, the authors hope their findings will spur more research on the economic consequences of antimicrobial resistance, whether analyses of hospital costs or studies of livestock loss. Such findings could inform models and improve their accuracy.

Although the World Health Organization has initiated a Global Action Plan on Antimicrobial Resistance, the authors support a larger international effort closer in scale to the Intergovernmental Panel on Climate Change. “There’s a need for a similar effort—for interchange of information, for discussion of what policies are best for different countries, and to continue to assess the global impact,” says economist and study author Delfin Go of The World Bank. “The potential cost of inaction is going to be high. It is too high to ignore.”