Bacterial illnesses that are resistant to available antibiotic medicines will cause more than 39 million deaths worldwide over the next 25 years and indirectly contribute to an additional 169 million deaths, according to a forecast published on Monday.

By 2050, annual death tolls attributed directly to antibiotic resistance, or associated with it, will reach 1.91 million and 8.22 million, respectively, if remediation measures are not in place, an international team of researchers reported in The Lancet.

Those annual numbers represent increases of nearly 68% and 75% per year, respectively, over death tolls directly and indirectly attributed to antibiotic resistance in 2022, the researchers with the Global Research on Antimicrobial Resistance Project wrote.

The increases will strain health systems and national economies and contribute to annual gross domestic product losses of $1 trillion to 3.4 trillion by 2030, they predict.

The forecast of how the antibiotic resistance burden is likely to evolve was released ahead of a Sept. 26 United Nations General Assembly High Level Meeting on the subject.

“This landmark study confirms that the world is facing an antibiotic emergency, with devastating human costs for families and communities across the world,” Dame Sally Davies, the Special Envoy on Antimicrobial Resistance for the UK and a member of the UN Interagency Coordination Group on Antimicrobial Resistance, said in a statement. She was not involved in the research.

Resistance to antimicrobials appears to pose the biggest threat to the elderly, with deaths in adults over age 70 increasing by more than 80% between 1990 and 2021, according to the report.

Low- and middle-income countries face a disproportionate burden, with the highest rates of antibiotic-resistance-related deaths occurring in sub-Saharan Africa and South Asia, in particular from multi-drug resistant tuberculosis, researchers said.

Antibiotic resistance occurs when bacteria, viruses, fungi and parasites no longer respond to drugs, either because of genetic changes in these organisms or, more often, because of the misuse and overuse of the drugs to treat, prevent or control infections in humans, animals and plants, according to the World Health Organization.

Access to better care for serious infections, new vaccines to prevent infections, and more judicious medical protocols that limit antibiotic use to appropriate cases could save a total of 92 million lives between 2025 and 2050, they also predict.

Estimates for the new study were made for 22 types of disease-causing organisms, 84 combinations of drugs vs bacteria, and 11 infectious syndromes such as meningitis and sepsis.

The estimates were based on records from 520 million people of all ages in 204 countries from a wide range of sources, including hospital data, death records, and antibiotic use data.