A peer-reviewed article published in December 2025 in the Journal of Applied and Environmental Microbiology highlights the need for increased environmental surveillance for Salmonella to identify alternative reservoirs and transmission pathways. The publication is authored by scientists from the University of Georgia (UGA) and the Office of Laboratory Operations and Applied Science, Human Foods Program, FDA. 

The publication presents findings from a two-year (Nov 2021-Oct 2023) watershed Salmonella surveillance conducted across four watersheds in the Southeastern U.S. Briefly, the study assessed the prevalence of Salmonella in water samples (n=456) collected from 19 sites. For positive samples, Whole-Genome Sequencing (WGS) was used for serovar identification, diversity assessment and antimicrobial susceptibility testing. These sequences were further analyzed in phylogenetic studies using existing NCBI libraries for national food animal production. In addition, adjacent land-use and weather data were collected to examine the relationships between these variables and the microbiological findings.  

Key Findings: 

• The Salmonella positivity rate was 69% (314/456), with prevalences ranging between 78% (112/144, Watershed C) and 63% (91/114, Watershed A), both watersheds adjacent to animal agriculture. 

• A total of 37 serovars were identified, with the most common across all watersheds being Give I, Rubislaw, Montevideo II, and Rubislaw. Salmonella serovars significant for human health included Infantis, Typhimurium, Montevideo, Braenderup, Mississippi, Muenchen and Saintpaul. 

•  The majority of serovars recovered from the water samples did not match the USDA-FSIS publicly available genomes for meat and poultry products (beef, chicken, pork and turkey), except for Infantis and Typhimurium (although they were genetically distinct from the NCBI), indicating that most of the serovars found in the watershed did not match those in the animal agriculture data, and suggesting the presence of additional Salmonella reservoirs beyond animal agricultural. 

• Seasonality was reported as an important factor in Salmonella prevalence and diversity, with the highest prevalence observed in the spring months (93%, 106/144). Similarly, 94% of the serovars were detected in the same months. On the other hand, the lowest prevalence was observed in the summer months (47%, 54/114). 

• Out of the 314 Salmonella-positives, 33 (11%) displayed antibiotic-resistance phenotypes, with 7(21%) being multidrug resistant. Antibiotics included, but were not limited to, streptomycin, tetracycline, chloramphenicol, nalidixic acid, amoxicillin and gentamicin. 

Why these matters 

• Salmonella serovars from wildlife are understudied, and as described in the study, multiple serovars might be introduced into water bodies via fecal contamination, where they may persist and subsequently contaminate irrigation sources used in produce production. This transmission pathway has been implicated in several produce-related outbreaks.  

• According to the publication, 60-80% of salmonellosis cases are not linked to a known outbreak; meanwhile, 44% of domestic Salmonella illness is attributed to produce consumption, underscoring the role of environmental reservoirs and irrigation water as potential contamination routes. 

• There are knowledge gaps in understanding Salmonella reservoirs in water sources. Increasing environmental surveillance, especially by expanding publicly available Salmonella genomes, could help identify outbreak strains faster and improve epidemiological traceback. Similar approaches have already proven useful in recreational water studies of Shiga toxin–producing E. coli (STEC), where characterizing the REP strain helped resolve outbreaks more effectively. 

• Methodological disparities in water sampling need to be addressed because culture-based methods can yield limited results. This underscores the need for more robust tools to improve Salmonella population assessment within watersheds, such as an amplicon-based next-generation sequencing approach that profiles the relative frequencies of multiple Salmonella serovars in a single sample. 

The One Health approach: The publication encourages us to think “outside the box,” challenging our tendency to focus primarily on familiar serovars and well-known sources of contamination. This habitual approach can hinder our ability to detect emerging risks and fully understand the complexity of public health. It is important to view the environment and the dynamic system through different lenses to continue advancing food safety and protecting public health. The study highlights the importance of interdisciplinary approaches to tackling public health challenges, including integrating land use data, leveraging publicly available databases and strengthening environmental water surveillance.