Study Reveals Muscid Flies as Hidden Vectors of Zoonotic Pathogens

In a groundbreaking study published in the journal *npj Biofilms and Microbiomes*, researchers have uncovered that muscid flies, specifically *Neomyia cornicina*, can serve as vectors for zoonotic pathogens and antibiotic resistance genes (ARGs) on dairy farms. This research, conducted by a team from the University of Clermont Auvergne in France, highlights the potential public health risks associated with these insects, which thrive in cow manure and may facilitate the transmission of harmful microbes.

The study was spearheaded by Dr. Anna Sommer, a microbiologist at the university, who emphasized the significance of their findings. "Flies not only transport pathogens but may also amplify their presence, posing a serious risk for disease transmission, particularly to farm workers and local communities," Dr. Sommer stated in an official press release on June 22, 2025.

Historically, over 60% of emerging infectious diseases (EIDs) have been linked to animal origins, with dairy farms being recognized as breeding grounds for zoonotic bacteria such as *Escherichia coli* and *Salmonella enterica*. These pathogens often harbor antibiotic resistance genes, raising concerns about their impact on public health. The researchers utilized deep metagenomic sequencing techniques to identify and trace the flow of pathogens from dairy cattle manure into the gastrointestinal tracts (GITs) of the flies.

The research methodology involved collecting 29 adult flies from a dairy farm in Saint-Genès-Champanelle, France. The flies were captured while feeding on or hovering above manure. After molecular identification, their GITs underwent DNA extraction and sequencing. This approach allowed the team to analyze genomic similarities between the flies and the manure samples, revealing that a significant overlap exists in the microbial communities.

Results indicated that the flies carried pathogens and ARGs that were enriched in their GITs. Specifically, the study identified eight pathogen genomes, including those of *E. coli* O111 and O157 and *Coxiella burnetii*, the agent responsible for Q fever. Alarmingly, the presence of these pathogens was often found in higher concentrations within the flies compared to the manure, suggesting a potential for bacterial proliferation post-ingestion.

Dr. John Turner, a veterinary epidemiologist at the University of California, Davis, provided insight into the implications of these findings. "The mobility of flies enables them to spread pathogens beyond the confines of the farm, potentially impacting surrounding ecosystems and human populations," Dr. Turner remarked. This sentiment is echoed by Dr. Sarah Johnson, an expert in zoonotic diseases at the University of Edinburgh, who highlighted the urgent need for integrated pest management strategies on farms to mitigate these risks.

The study also addressed the relationship between antibiotic use on farms and the prevalence of ARGs found in the flies. Although records indicated the use of antibiotics correlating with the detection of certain resistance genes, no statistical correlation was established between specific usage patterns and ARG abundance, suggesting that environmental factors may also play a significant role in shaping these microbial communities.

In light of these findings, the researchers advocate for further longitudinal studies across multiple farms to validate their results and better understand the dynamics of pathogen transmission through flies. The research team emphasizes the importance of interdisciplinary approaches combining microbiology, veterinary medicine, and public health to address these emerging threats effectively.

In conclusion, this study signifies a critical advancement in understanding the role of insects as vectors in the transmission of zoonotic diseases, urging for immediate action in agricultural practices to ensure public health safety. As Dr. Sommer aptly noted, "The intersection of agriculture and public health is where we must focus our efforts to prevent future outbreaks of zoonotic diseases."