Analysis reveals exposure, health risks of antibiotic resistance genes in farm air

News brief

Young Asian girl with chickens — *EyeEm Mobile GmbH / iStock*

A study of Chinese farms suggests livestock air could be a significant source of exposure to antibiotic resistance genes (ARGs) for farmworkers and surrounding residents, researchers reported yesterday in PNAS.

While several studies have identified the presence of ARGs in the air of livestock farms, the comprehensive health risk presented by antibiotic resistomes (the collection of acquired ARGs) in livestock air is less well understood. To evaluate human exposure and the health risks of air resistomes on livestock farms, Chinese researchers sampled total suspended particles from pig farms, chicken farms, near-farm residential areas, and urban areas and conducted metagenomic analysis on extracted bacterial DNA. They also compared the air resistomes on Chinese farms with those in Europe, which has a longer history of restricting antibiotic use in food-animal production than China.

The analysis found that livestock air on Chinese farms was highly enriched with ARGs. The resistome abundance observed on chicken and pig farms and near-farm residential areas was more than seven times higher than found in urban air samples, and the daily ARG inhalation of farm workers was equivalent to several years of ARG inhalation by urban residents. Residents living near two of the farms inhaled over 10 times more ARGs per day than urban residents. The ARGs identified in livestock air were highly associated with mobile genetic elements.

Reduced risk on European farms compared with Chinese farms

The diversity, abundance, and risk score of air resistomes on Chinese farms were also significantly higher than those on farms in nine European countries, a finding the researchers say suggests long-term restrictions on antibiotic use mitigates antibiotic resistance in the livestock environment. But they note that, even with more judicious antibiotic use, the resistome risk score on European farms was significantly higher than in other known ARG hot spots, including hospital and sewage plant air, animal manure, and soil.

"Our results underscore the high exposure of farm workers to ARGs via farm air and highlight its role in ARG dissemination, supporting the importance of antibiotic stewardship practices in combating antibiotic resistance," the authors concluded.

Top virologists urge world leaders to act on rising avian flu threat

News brief

Mary Van Beusekom, MS

Flock of wild birds — *Swati Kulkarni / Flickr cc*

In a commentary in The Lancet Regional Health–Americas, leading virologists from more than 40 countries are exhorting global leaders to address the increasing threat of H5N1 avian flu by boosting surveillance, enhancing biosecurity, and preparing for potential human-to-human viral transmission.

The Global Virus Network (GVN) scientists review the US outbreak status, discuss the importance of robust surveillance systems to detect emerging strains with pandemic potential, spotlight the risks facing the dairy and poultry industries, and recommend risk mitigation strategies.

The authors note that more than 995 dairy cow herds and at least 70 people have been infected with H5N1, including severe cases and the first reported US death.

Continued investment in surveillance at the human-animal interface, and immediate sharing of unusual field observations and sequence data is essential for researchers worldwide to monitor virus dynamics effectively.

Marion Koopmans, DVM, PhD

"In the U.S. sporadic human infections with no known contact with infected animals highlight the possibility of viral adaptation for efficient human-to-human transmission," they write. "Concurrently, the virus continues to circulate in wild birds, backyard flocks, and hunted migratory species, further amplifying the risk to humans and domestic animals."

Surveillance, data sharing needed

The researchers recommend:

Continuously monitoring animals, including testing milk, wastewater, and people working with infected animals, to track virus evolution that may lead to human-to human transmissibility.
Accelerating the sharing of genomic data among global research networks to track virus evolution and spread.
Using personal protective equipment and strict farm-cleaning protocols.
Advocating for self-administered diagnostic tests for farm workers and healthcare access for frontline medical workers.
Providing more funding for response mechanisms, especially in high-risk regions.
Investing in predicting traits of avian flu viruses from genetic data rather than from genomic sequences alone.
Developing and rapidly deploying vaccines for people and animals.
Conducting clinical studies on the properties of emerging virus strains and on potential therapies and vaccines.

"Continued investment in surveillance at the human-animal interface, and immediate sharing of unusual field observations and sequence data is essential for researchers worldwide to monitor virus dynamics effectively," senior author Marion Koopmans, DVM, PhD, of Erasmus Medical Center in the Netherlands, said in a GVN news release.

Seasonal flu vaccine uptake rose among Black, Hispanic Americans

News brief

Stephanie Soucheray, MA

man getting shot — Troy Saunders, SPG News/Flickr cc

Uptake of the seasonal influenza vaccine has held mostly steady in recent years, but Black and Hispanic adults have seen more uptake, according to an analysis published earlier this month in JAMA Network Open.

The study is based on responses to the 2019 and 2022 Medicare Consumer Assessment of Healthcare Providers and Systems surveys, which were used to create a weighted sample of 285,265 community-dwelling Medicare Advantage and Medicare Fee-for-Service enrollees aged 65 years or older.

More than half, 54.5%, of respondents were women. Two-thirds, 76.2%, were White; 8.0% were Black; 6.9% were Hispanic; and 4.2% were Asian, Native Hawaiian, or other Pacific Islander.

Rural White adults see drop

Overall, between 2019 and 2022, overall influenza vaccination rates for older adults increased 0.7 percentage points (95% confidence interval [CI], 0.2 to 1.1), from 76.3% to 77.0%, the authors said. For White and Asian adults, percentages remained unchanged, but Black and Hispanic adults, especially those living in rural communities, saw a significant increase in uptake.

Black adults with seasonal flu shots increased 7.0 percentage points (95% CI, 0.3 to 13.8) and Hispanic adults by 8.2 percentage points (95% CI, 0.8 to 15.5). In sharp contrast, White adults in rural areas saw uptake drop by 2 percentage points over the study period.

Determining the reasons for these divergent changes is a high priority for future studies.

“Determining the reasons for these divergent changes is a high priority for future studies,” the authors concluded. “However, these descriptive findings are important to policymakers as they make decisions about how to invest in interventions that could influence influenza vaccination rates for populations with lower rates of uptake.”