Listeria is a genus of bacteria known for its resilience and ability to thrive in diverse environments. Among its species, Listeria monocytogenes is particularly pathogenic, posing significant public health concerns. Its presence in various environments, including soil, water, and the feces of animals, allows it to contaminate a wide range of foods, such as dairy, meat, and especially fresh produce. The bacterium’s ability to survive and multiply at refrigeration temperatures exacerbates the challenges of controlling its presence within the food supply chain, making it a formidable threat to global food safety systems ( Farber and Peterkin, 1991; Swaminathan and Gerner-Smidt, 2007). Recent studies have confirmed the persistence of the bacterium in environments where food are processed and its resistance to sanitizers, complicating food safety efforts ( Melero et al., 2021; Di Ciccio et al., 2022).

Listeriosis, the infection caused by L. monocytogenes, can lead to severe outcomes, ranging from mild gastroenteritis in healthy individuals to more invasive diseases such as meningitis, septicemia, and miscarriages in vulnerable populations, which include pregnant women, neonates, the elderly, and individuals whose immune system has been compromised. The disease’s wide range of clinical manifestations underscores the necessity for robust surveillance, accurate diagnostic tools, and effective prevention strategies to mitigate this public health threat ( Scallan et al., 2011; Allerberger and Wagner, 2010). Recent research emphasizes the importance of rapid detection methods, such as PCR-based techniques, in improving early diagnosis and treatment outcomes.

In recent years, the link between fresh produce consumption and listeriosis outbreaks has attracted significant attention. Fresh fruits and vegetables can become contaminated through exposure to contaminated soil, water, or manure used as fertilizer. Post-harvest activities, such as washing and packing, may further introduce or disseminate the bacterium. Leafy greens and sprouts, in particular, have been implicated in outbreaks due to their propensity to harbor and support L. monocytogenes growth. This highlights the importance of assessing the prevalence and survival of Listeria in produce-growing environments to inform public health interventions directed at limiting listeriosis incidence ( Olaimat and Holley, 2012; Beuchat, 2002). Recent investigations into microbial ecology in farming systems have found that certain biofilms formed by L. monocytogenes on equipment can be a significant contamination source ( Rodriguez-Lopez et al., 2020; Kovačević et al., 2023).

The persistence of L. monocytogenes in agricultural environments is a testament to its adaptability. Several factors, including soil type, agricultural practices, and the use of contaminated irrigation water, influence the prevalence of Listeria. Research shows that L. monocytogenes not only survives but thrives under various environmental conditions, complicating control efforts in agricultural settings. Investigating the prevalence of Listeria across different geographic regions and farming systems is essential to understanding the extent of this issue and developing targeted control measures ( Carlin et al., 2013; Nightingale et al., 2005). Recent studies have also explored the genetic adaptability of L. monocytogenes, highlighting mutations that confer enhanced survival in harsh conditions ( Lianou et al., 2021).

Evaluating Listeria contamination levels in fresh produce is critical for assessing consumer risk and informing risk management strategies. Data from surveillance and outbreak investigations have offered valuable insights into contamination levels and the types of produce most frequently implicated in listeriosis cases. These findings are crucial for guiding industry practices and regulatory policies to minimize L. monocytogenes contamination in fresh produce ( Todd et al., 2009; Gombas et al., 2017). Produce contamination has raised the need for more surveillance and periodic assessment, as well as stricter regulatory frameworks and advanced detection systems to monitor contamination more effectively ( Schlech et al., 2022).

This systematic review was conducted following PRISMA guidelines (Supplementary Material 1; S1) ( Moher et al., 2021). These rigorous standards ensure transparency and replicability in the review process.

This meta-analysis aimed to consolidate current knowledge regarding the prevalence of Listeria spp., particularly Listeria monocytogenes, in fresh produce. Analyzing data from 12 studies, our findings reveal significant heterogeneity (I ² = 97.79%, p < 0.0001), underscoring the variability of Listeria prevalence across different geographical regions, types of produce, and study methodologies. Such variability aligns with previous research, which has noted challenges in accurately estimating the prevalence of Listeria due to diverse sampling techniques, detection methods, and agricultural practices ( Farber and Peterkin, 1991; Swaminathan and Gerner-Smidt, 2007; Gombas et al., 2017).

The substantial heterogeneity observed suggests that factors such as geographical region, type of produce, and study design significantly influence Listeria prevalence rates. This finding corroborates Beuchat (2002), who highlighted that environmental conditions and region-specific agricultural practices can affect the presence and proliferation of Listeria within the food supply chain. Our attempts at subgroup analysis, albeit limited by methodological constraints, hint at a complex interplay among these factors, which warrants further investigation ( Rodriguez-Lopez et al., 2020; Melero et al., 2021).

The contrasting results from Begg’s rank correlation test (p = 0.8406) and Egger’s weighted regression test (p = 0.0223) provide intriguing insights into potential publication bias or small-study effects. While Begg’s test did not indicate significant publication bias, Egger’s test suggested funnel plot asymmetry, implying that smaller studies reporting higher prevalence rates may be more likely to be published. This observation is consistent with existing literature, which has documented a tendency to underreport studies with null or negative results ( Easterbrook et al., 1991; Todd et al., 2009).

Our sensitivity analysis confirmed the robustness of the pooled prevalence estimates, indicating that no single study disproportionately influenced the overall findings. This robustness is critical for the reliability of meta-analytical conclusions, especially in fields where outcomes can vary widely due to methodological differences ( Higgins and Green, 2011; Di Ciccio et al., 2022).

The meta-regression analysis revealed that the total sample size did not significantly moderate Listeria prevalence, suggesting that other, unexamined factors may be at play. This finding aligns with the understanding that the dynamics of foodborne pathogens are influenced by a complex array of factors beyond simple demographic or quantitative measures ( Carlin et al., 2013; Nightingale et al., 2005). Recent studies also suggest that biofilm formation by Listeria in food processing environments could contribute to its persistence, further complicating contamination control ( Kovačević et al., 2023).

The occurrence of Listeria in fresh produce represents a major public health risk, especially for vulnerable groups such as pregnant women, newborns, and individuals with compromised immune systems ( Scallan et al., 2011). Our findings underscore the urgent need for comprehensive surveillance and targeted intervention strategies that consider the specific agricultural practices and environmental conditions unique to each region ( Schlech et al., 2022; Lianou et al., 2021).

Future research should focus on disentangling the effects of various potential moderators on Listeria prevalence. Employing more sophisticated statistical models and larger datasets will be essential to overcoming the limitations observed in the current analysis. Additionally, investigating the impact of specific agricultural practices and supply chain processes on Listeria prevalence could yield valuable insights for mitigating contamination risks in fresh produce).

This meta-analysis highlights significant heterogeneity in the prevalence of Listeria spp. in fresh produce, raising critical questions about the factors contributing to this variability. The potential for publication bias and the robustness of our findings, as demonstrated through sensitivity analysis, underscore the complexity involved in estimating the true prevalence of this pathogen. Addressing the challenges posed by Listeria in fresh produce necessitates a multifaceted approach that integrates public health initiatives, agricultural practices, and advanced research methodologies. Effective strategies must be tailored to regional contexts to mitigate the risks associated with Listeria contamination and protect vulnerable populations. This study also revealed the scarcity of elaborate studies on Listeria monocytogenes, giving credence to the importance of this ongoing Nigeria-NRF-sponsored study in this area.

Conception of research idea (AA), Literature review (OF and UO), Research protocol design (AA, AAA and OF), Study appraisal (OF, AA, UO and AAA), Data extraction (OF, and UO), Data analysis and interpretation of results (OF, AA, and OA), Manuscript drafting (OF, AA, UO and OA), and review of the initial and final draft of the manuscript (OF, AA, UO and OA).

Zenodod Repository: PRISMA checklist for ‘Systematic review and meta-analysis of the occurrence of Listeria monocytogenes in fresh produce in selected developing countries’. https://doi.org/10.5281/zenodo.14224887 ( Fatunla and Adegoke, 2024).

This dataset is licensed under the Creative Commons Zero v1.0 Universal license, allowing for sharing and adaptation with appropriate credit.

Not Applicable.

No human subjects were studied but all authors approved the submission.