Researchers have developed a new critical warning system for the spread of antimicrobial resistant (AMR) superbugs: poop and pee from airplane bathrooms.

Scientists predict that by 2050, AMR superbugs, or pathogens that don’t respond to antimicrobial medicines, might take more lives than cancer. As such, it’s critical for countries to keep an eye on the global propagation of these dangerous pathogens, which can travel with people, in order to best prepare for future infections. In a study published in May in the journal Microbiology Spectrum, a team of international researchers suggests that aircraft toilet wastewater could warn authorities about the arrival of such superbugs.

“Long-haul flight aircraft wastewater may serve as a representative microbial footprint, often of mixed country origin, offering valuable insight into the movement of pathogens and antimicrobial resistance (AMR) on a global scale,” the team wrote in the study. “Herein, we present a proof-of-concept for aircraft-based surveillance of AMR by investigating lavatory wastewater samples from 44 repatriation flights to Australia departing from nine countries.”

What did researchers find in airplane toilet wastewater?

The analysis revealed nine dangerous pathogens, including some superbugs that are resistant to more than one drug. The team investigated the superbugs’ genetic signatures and antibiotic resistance gene (ARG) profiles, finding a gene that lends resistance to last-resort antibiotics on 17 flights. Interestingly, this dangerous gene was not present in Australia’s urban wastewater at the time, indicating its arrival via international travel. All 44 flight samples had five out of the nine superbugs.

“Aircraft wastewater captures microbial signatures from passengers across different continents, offering a non-invasive, cost-effective way to monitor threats like AMR,” Warish Ahmed, a senior author of the study and researcher from CSIRO, said in a University of South Australia statement.

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Eighteen of the flights came from India, 14 from the United Kingdom, six from Germany, and one each from France, the United Arab Emirates, Turkey, South Africa, Japan, and Indonesia. According to Nicholas Ashbolt, a co-author of the study and a microbiologist at the University of South Australia, flights from Asia, especially from India, revealed greater concentrations of antibiotic-resistance genes than those from Europe and the United Kingdom. These distinctions could be due to differences in antibiotic use, water sanitation, population density, and public health policies.

“International travel is one of the major drivers of AMR spread,” said Yawen Liu, lead author of the study and a postdoctoral fellow at Xiamen University. “By monitoring aircraft wastewater, we can potentially detect and track antibiotic resistance genes before they become established in local environments.” Tuberculosis, influenza, and SARS-CoV-2, for example, can also spread by air travel.

Wastewater could provide a warning system for superbugs

While the researchers collected the wastewater samples from Covid-19 pandemic repatriation flights, potentially swaying passenger demographics, they argue that similar methods can also work for regular international travel.

“With AMR projected to cause more than 39 million deaths globally by 2050, the need for innovative surveillance tools is urgent,” Ashbolt concluded. “Aircraft wastewater monitoring could complement existing public health systems, providing early warnings of emerging superbug threats.”