ANTIBIOTICS were heralded as life-savers when they became widely available in the 1940s. Today, they are fast becoming killers themselves. The more any given antibiotic is used, the greater the chances that bacteria will develop antimicrobial resistance (AMR) that renders the drug ineffective. Widespread overuse of antibiotics has made AMR a fast-growing plague. By one estimate, 700,000 people currently succumb to antibiotic-resistant infections every year. If current trends continue, the number of deaths will rise to a devastating 10m people a year by 2050. That toll would amount to $100trn in foregone economic output, according to a review published in 2016 by the British government and the Wellcome Trust.

In late 2016 the UN General Assembly launched a global coordinated effort to tackle AMR with more research, better regulation and more alternatives to antibiotics. It was just the fourth time that the UN’s members had made a commitment to a health-related cause. The first challenge is simply acquiring the data necessary to assess the scope of the threat and evaluate progress. Just 50 countries were enrolled in the UN’s surveillance system to track the prevalence of AMR in December 2017, and only 22 have produced data so far.

In the meantime, a more direct method would be to measure the consumption of antibiotics themselves. A new paper published in the Proceedings of the National Academy of Sciences gathers together figures from 76 countries between 2000 and 2015. It estimates that consumption of antibiotics in these countries increased by a hefty 65% during that time period, from 21bn defined daily doses (DDD) to nearly 35bn. Their rate of DDD, a standardised measurement of dosage across different drug types, also increased by 39% from 11.3 to 15.7 per 1,000 people.

As with other aspects of development, while rich countries are changing their behaviour, poorer ones are adopting their bad habits. Although developed economies cut their use of antibiotics by 4% in the 16 years to 2015, consumption soared by 75% in the rest of the world. Even between countries with similar average incomes, antibiotic use varies wildly: doses per 1,000 people were over seven times higher in Turkey than in Mexico in 2015. The paper’s authors could not identify the causes of these gaps: they found no link between antibiotic use and the number of measles vaccinations (as a proxy for public health interventions); nor the number of doctors (as a proxy for quality of health care).

Within developing countries, the researchers did find that a 1% increase in GDP per person was associated with a rise in antibiotic usage of 3.1 DDD per 1,000 people. That might be because urbanisation so often goes hand-in-hand with GDP growth: lack of clean water and sanitation causes diseases such as typhoid fever, while poor air quality and use of dirty fuels for cooking causes respiratory infections. Both ailments are treated with antibiotics, with bigger doses and increasing potency in order to combat rising AMR.

Thankfully, antibiotic use in China and India, the world’s two most populous countries, is still below the global average. But they are quickly catching up: daily dosage per person has risen by 65% in India and 70% in China since 2000. If they and other countries continue on this path, the researchers project that global antibiotic use could reach a feverish 125bn dosages a day, up from 42bn in 2015. “Antimicrobial resistance will take us back to a time when people feared common infections and risked their lives from minor surgery", said the head of the UN’s World Health Organisation when he launched World Antibiotic Awareness Week in November 2017. “[It is] a global crisis that we cannot ignore”.