Passengers as Pathways: Behavioral Evidence on Travelers’ Knowledge of African Swine Fever Introduction Through Pork Products
, Giulia Murgia 1,†, Katia Usai 2, Riccardo Bazzardi 3, Gaia Muroni 2, Stefano Cappai 2, Annamaria Coccollone 1 and Federica Loi 2,*Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Comments and Suggestions for the Authors
The manuscript entitled “Passengers as Pathways: Assessing the Risk of African Swine Fever Introduction Through Traveler-Borne Pork Products” presents an interesting and relevant study based on a questionnaire administered to air travelers, aimed at assessing their knowledge of African swine fever (ASF) and exploring this approach as a potential tool to increase awareness of the disease.
The study provides novel insights into the risk of introduction or reintroduction of ASF virus (ASFV) into free territories and offers valuable information for prevention strategies. In particular, the results highlight an extremely low level of ASF awareness among travelers, which is a matter of concern and clearly underlines the importance and necessity of this type of investigation. These findings could be useful for integrating additional measures into post-eradication surveillance and prevention strategies aimed at managing the risk of ASF introduction.
Overall, the manuscript is well structured and supported by informative tables and figures. I believe that this work could represent a valuable contribution to the existing literature. Only a limited number of revisions are suggested in order to further improve the manuscript.
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Major Comments
- Lines 66–69 Sardinia had already been affected by a long-distance introduction of ASF when genotype II was detected in the Nuoro province in 2023, likely linked to the improper waste derived from infected meat and meat products originating from mainland Italy. This event has been reported in previous scientific publications. Citing this episode could enrich the background section and strengthen the discussion on the risk associated with human-mediated pathways.
- Line 104 The authors state: “The present study addresses this gap by using a questionnaire-based approach administered to air and sea travelers…”. However, in the Discussion section, the limitations of the study indicate that “the study was conducted only in airports and therefore does not capture passenger flows arriving by sea” (line 314). The authors are kindly requested to clarify this apparent inconsistency.
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Minor Comments
- Line 115: Please remove the parentheses after the word “region”.
- Line 179: Please add a space between “Figure 3” and (…).
- Line 207: Please replace “Sapin” with “Spain”.
Author Response
Rev. 1
Comments and Suggestions for the Authors
The manuscript entitled “Passengers as Pathways: Assessing the Risk of African Swine Fever Introduction Through Traveler-Borne Pork Products” presents an interesting and relevant study based on a questionnaire administered to air travelers, aimed at assessing their knowledge of African swine fever (ASF) and exploring this approach as a potential tool to increase awareness of the disease.
The study provides novel insights into the risk of introduction or reintroduction of ASF virus (ASFV) into free territories and offers valuable information for prevention strategies. In particular, the results highlight an extremely low level of ASF awareness among travelers, which is a matter of concern and clearly underlines the importance and necessity of this type of investigation. These findings could be useful for integrating additional measures into post-eradication surveillance and prevention strategies aimed at managing the risk of ASF introduction.
Overall, the manuscript is well structured and supported by informative tables and figures. I believe that this work could represent a valuable contribution to the existing literature. Only a limited number of revisions are suggested in order to further improve the manuscript.
----------------------------------------------------------------------------------------------------------
Major Comments
- Lines 66–69 Sardinia had already been affected by a long-distance introduction of ASF when genotype II was detected in the Nuoro province in 2023, likely linked to the improper waste derived from infected meat and meat products originating from mainland Italy. This event has been reported in previous scientific publications. Citing this episode could enrich the background section and strengthen the discussion on the risk associated with human-mediated pathways.
Response: Thank you very much for this suggestion, we cite this reference and discuss this point in the updated version of the manuscript.
- Line 104 The authors state: “The present study addresses this gap by using a questionnaire-based approach administered to air and sea travelers…”. However, in the Discussion section, the limitations of the study indicate that “the study was conducted only in airports and therefore does not capture passenger flows arriving by sea” (line 314). The authors are kindly requested to clarify this apparent inconsistency.
Response: Unfortunately, the Sardinian port did not accept the collaboration, thus this study was carried out only at the airport. We specified this point in the discussion. Thank you for this observation.
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Minor Comments
- Line 115: Please remove the parentheses after the word “region”.
Response: done
- Line 179: Please add a space between “Figure 3” and (…).
Response: done
- Line 207: Please replace “Sapin” with “Spain”.
Response: done
Reviewer 2 Report
Comments and Suggestions for Authors
Excellent work! Important question. Good methods. Very well written. Appropriate discussion. Sound conclusions. Should be appreciated by pork industries worldwide.
Of interest to this reviewer and not questions that need to be addressed in this manuscript, maybe in future surveys: Were the pork products uncooked? Were they being taken by the original maker to guests? Or were travelers returning home with meat products given to them? Products homemade? Commercially manufactured pork products presumed to be fully cooked, are they? The concern with ASFv is said to be in uncooked products that are improperly disposed of and eaten by feral pigs (as the authors have written).
I support the publication of this work.
Author Response
Excellent work! Important question. Good methods. Very well written. Appropriate discussion. Sound conclusions. Should be appreciated by pork industries worldwide.
Of interest to this reviewer and not questions that need to be addressed in this manuscript, maybe in future surveys: Were the pork products uncooked? Were they being taken by the original maker to guests? Or were travelers returning home with meat products given to them? Products homemade? Commercially manufactured pork products presumed to be fully cooked, are they? The concern with ASFv is said to be in uncooked products that are improperly disposed of and eaten by feral pigs (as the authors have written).
I support the publication of this work.
Response: thank you very much for your comments and for the time you spent in this revision. We strongly believe in this work and we understand this is a preliminary work and preliminary results. We decided to not ask too many questions to the travelers because this could hinder their participations. Otherwise, all these points must be investigated (Were the pork products uncooked? Were they being taken by the original maker to guests? Or were travelers returning home with meat products given to them? Products homemade? Commercially manufactured pork products presumed to be fully cooked, are they?) and we take your suggestion to empathize this in the discussion. Thank you very much!
Reviewer 3 Report
Comments and Suggestions for Authors
General assessment
The manuscript addresses a relevant and timely topic, namely the potential role of passenger-borne pork products in the introduction or reintroduction of African swine fever (ASF), particularly in a post-eradication setting such as Sardinia. The large number of collected questionnaires is a positive aspect, and the focus on human behavior as a complementary surveillance component is conceptually sound.
However, in its current form, the manuscript presents substantial conceptual, methodological, and structural weaknesses. The study is largely descriptive, while the title, abstract, and discussion repeatedly imply a risk assessment, which is not supported by the data or analytical approach used. Several key elements required for scientific reproducibility and epidemiological interpretation are missing or insufficiently described.
Major comments
- Conceptual overstatement of “risk assessment”
The manuscript repeatedly claims to “assess the risk” of ASF introduction or reintroduction. However, the study does not perform a risk assessment, either qualitative or quantitative.
What is actually presented:
- Self-reported awareness of ASF
- Self-reported transport of pork products
What is not addressed:
- Probability of ASFV presence in transported products
- Product type (raw vs processed, cured, heat-treated)
- Virus survival
- Exposure likelihood to domestic pigs or wild boar
- Any formal risk framework
This mismatch between claims and evidence represents a major conceptual flaw.
Recommendation:
The authors must either:
- Substantially reframe the manuscript as a behavioral or exposure-proxy study, or
- Explicitly state that the work provides behavioral indicators relevant to qualitative risk assessment, not a risk assessment itself.
- Questionnaire design and reproducibility
The questionnaire is central to the study, yet:
- The exact wording of questions is not provided
- It is unclear whether multiple answers were allowed
- “Pork products” are not defined (raw, cured, commercial, homemade)
- It is not specified whether posters explaining ASF were visible before questionnaire completion, which could strongly bias responses
This limits transparency and reproducibility.
Recommendation:
The full questionnaire should be provided as Supplementary Material, and potential information bias must be explicitly discussed.
- Selection bias and self-reporting bias
Participation was:
- Voluntary
- Almost entirely QR-code based (≈99%)
- Self-reported and potentially legally sensitive
This strongly suggests selection bias and likely underreporting of risky behavior. Although briefly mentioned, this limitation is underestimated in the discussion.
Recommendation:
The authors should more explicitly acknowledge that the prevalence of pork transport may be underestimated and that results cannot be generalized to all travelers.
- Inadequate description of Materials and Methods
Several critical elements are missing from the Materials and Methods section:
- Statistical methods are not described, despite being reported in the Results
- The survey period is not clearly stated in M&M
- Software and significance thresholds are not specified
This is a major methodological omission.
- Figures 1 and 2 placement
Figures 1 and 2 are photographs documenting logistics and posters, not scientific figures.
- They do not contribute to the analytical results
- They should not appear in the main body of the manuscript
Recommendation:
Move Figures 1 and 2 to Supplementary Materials or remove them entirely.
Results section – major issues
- Terminology and clarity
- Line 169 uses the term “not-normal distribution”, which is not standard scientific terminology.
- This should be corrected to “non-normal distribution” or replaced with a clear statement on how normality was assessed.
- Irrelevant analyses
- The detailed description of weekday versus weekend passenger flow is not relevant to the study objectives and does not inform ASF introduction risk.
- In contrast, seasonality is epidemiologically relevant and should be retained.
Recommendation:
Remove or substantially reduce weekday-related analyses.
- Redundancy between table and text
- All results in Table 1 are fully repeated in the text, with identical percentages.
- This redundancy affects readability and scientific synthesis.
Recommendation:
Condense the Results section to highlight only key findings and avoid full numerical repetition
- URL formatting
- Line 117 contains an incorrect URL with a redundant “www.” before “https”.
- This should be corrected.
- Author Contributions section
- The Author Contributions section still contains placeholders (“X.X.”, “Y.Y.”).
- This must be completed before publication.
11. References
- Should follow the same format
Author Response
General assessment
The manuscript addresses a relevant and timely topic, namely the potential role of passenger-borne pork products in the introduction or reintroduction of African swine fever (ASF), particularly in a post-eradication setting such as Sardinia. The large number of collected questionnaires is a positive aspect, and the focus on human behavior as a complementary surveillance component is conceptually sound.
However, in its current form, the manuscript presents substantial conceptual, methodological, and structural weaknesses. The study is largely descriptive, while the title, abstract, and discussion repeatedly imply a risk assessment, which is not supported by the data or analytical approach used. Several key elements required for scientific reproducibility and epidemiological interpretation are missing or insufficiently described.
Major comments
- Conceptual overstatement of “risk assessment”
The manuscript repeatedly claims to “assess the risk” of ASF introduction or reintroduction. However, the study does not perform a risk assessment, either qualitative or quantitative.
What is actually presented:
- Self-reported awareness of ASF
- Self-reported transport of pork products
What is not addressed:
- Probability of ASFV presence in transported products
- Product type (raw vs processed, cured, heat-treated)
- Virus survival
- Exposure likelihood to domestic pigs or wild boar
- Any formal risk framework
This mismatch between claims and evidence represents a major conceptual flaw.
Recommendation:
The authors must either:
- Substantially reframe the manuscript as a behavioral or exposure-proxy study, or
- Explicitly state that the work provides behavioral indicators relevant to qualitative risk assessment, not a risk assessment itself
Response; thank to your suggestions, we agree with your point of view and a specific risk analysis is in place for more extensive work. Thus, we reformulate the title as: Passengers as Pathways: Behavioral Evidence on Traveler-Borne Pork Products Relevant to African Swine Fever Introduction. Furthermore, we explicitly stated that the work provides behavioral indicators relevant to qualitative risk assessment, not a risk assessment itself
- Questionnaire design and reproducibility
The questionnaire is central to the study, yet:
- The exact wording of questions is not provided
Response: The exact wording of questions was reported in Table 1, as specified in the main text. Furthermore, we included it in the supp.mat. as you suggested.
- It is unclear whether multiple answers were allowed
Response: Multiple answers were not included in the questionnaire and it is specified in the main text.
- “Pork products” are not defined (raw, cured, commercial, homemade)
Response: When we formulate the questionnaire, we take care about these point: Survey abandonment (if the questionnaire is too long, participants tend to abandon it before completing), reduced response quality (when respondents get tired, they start to respond hastily or superficially, for example by always selecting the same option); satisficing (“approximate” responses); response bias (fatigue leads to inconsistent or distorted responses that make the data unreliable); mobile device difficulties (mobile users struggle more with long questionnaires, increasing the likelihood that they will not complete the survey). We completely understand your concerns about this work, but we specified in the introduction that this is a starting point that could help the risk assessment and further investigation are needed. We know that several information are missing, but the risk in provide a long questionnaire able to answer your main question was at risk of non-respondent.
- It is not specified whether posters explaining ASF were visible before questionnaire completion, which could strongly bias responses
Response: as you can see in figure 2, the poster included ASF advice and QR-code to access to the questionnaire. The main goal of this project was both to advice and raise awareness, and collect answers about the travelers attitude.
This limits transparency and reproducibility.
Recommendation:
The full questionnaire should be provided as Supplementary Material, and potential information bias must be explicitly discussed.
Full questionnaire has been reported as full text in supplementary materials as you requested, information bias have been discussed.
- Selection bias and self-reporting bias
Participation was:
- Voluntary
- Almost entirely QR-code based (≈99%)
- Self-reported and potentially legally sensitive
This strongly suggests selection bias and likely underreporting of risky behavior. Although briefly mentioned, this limitation is underestimated in the discussion.
Recommendation:
The authors should more explicitly acknowledge that the prevalence of pork transport may be underestimated and that results cannot be generalized to all travelers.
Response: better empathized in discussion
- §Inadequate description of Materials and Methods
Several critical elements are missing from the Materials and Methods section:
- Statistical methods are not described, despite being reported in the Results
- The survey period is not clearly stated in M&M
- Software and significance thresholds are not specified
This is a major methodological omission.
Response: study design and statistical analyses sections have been added
- Figures 1 and 2 placement
Figures 1 and 2 are photographs documenting logistics and posters, not scientific figures.
- They do not contribute to the analytical results
- They should not appear in the main body of the manuscript
Recommendation:
Move Figures 1 and 2 to Supplementary Materials or remove them entirely.
Response: We acknowledge the reviewer’s concern regarding the placement of Figures 1 and 2. While these items are visually representative materials rather than primary data results, there is precedent in the scientific literature for including posters and awareness materials as methodological illustrations. For example, King et al. (2020) used interactive data-gathering posters as research tools and presented them as figures to illustrate methodology and context. Similarly, Rosli (2018) analyzes health campaign poster design with illustrative poster examples embedded as figures, and Hasanica et al. (2020) include educational poster visuals to depict intervention materials. These examples support the inclusion of such figures in Methods sections to enhance clarity and reproducibility.
We strongly believe the use of these figures in the main text could help the readers. Thus, considering that the other reviewers did not challenge the presence of these figures in the main text, and did not ask to move to supplementary materials, we ask the opinion of the editor before move on.
Results section – major issues
- Terminology and clarity
- Line 169 uses the term “not-normal distribution”, which is not standard scientific terminology.
Response: correct
- This should be corrected to “non-normal distribution” or replaced with a clear statement on how normality was assessed.
- Irrelevant analyses
- The detailed description of weekday versus weekend passenger flow is not relevant to the study objectives and does not inform ASF introduction risk.
- In contrast, seasonality is epidemiologically relevant and should be retained.
Recommendation:
Remove or substantially reduce weekday-related analyses.
Response: trend analyses were performed to compare data collected with official data available from the involved airports, in order to validate the sample.
- Redundancy between table and text
- All results in Table 1 are fully repeated in the text, with identical percentages.
- This redundancy affects readability and scientific synthesis.
Recommendation:
Condense the Results section to highlight only key findings and avoid full numerical repetition
Response: done
- URL formatting
- Line 117 contains an incorrect URL with a redundant “www.” before “https”.
- This should be corrected.
Response: done
- Author Contributions section
- The Author Contributions section still contains placeholders (“X.X.”, “Y.Y.”).
- This must be completed before publication.
Response: done
- References
- Should follow the same format
Response: done
Round 2
Reviewer 3 Report
Comments and Suggestions for Authors
The authors have demonstrated a high level of transparency and effort in addressing the substantial conceptual and methodological concerns raised in the first round of review. By reframing the study as "behavioral evidence" rather than a formal "risk assessment," the manuscript now aligns its claims with its actual analytical output. The addition of detailed statistical methods and the completion of administrative metadata significantly improve the paper's scientific rigor.
General Evaluation
The revised manuscript is significantly strengthened. The authors successfully shifted the focus toward the behavioral interface of African Swine Fever (ASF) introduction, which is a critical, often neglected component of transboundary animal disease (TAD) surveillance. The inclusion of specific epidemiological context—such as the 2023 genotype II introduction in Nuoro province—provides necessary urgency and justification for the study
Strengths of the Revised Version
- Reframing of Scope: The change in the title and abstract to emphasize "behavioral evidence" accurately reflects the nature of the data provided.
- Methodological Transparency: The addition of Sections 2.3 and 2.4, specifying the use of R software (Version 4.5.2) and appropriate non-parametric tests (Kruskal-Wallis, Mann-Whitney), resolves the previous lack of reproducibility.
- Knowledge vs. Action Paradox: The deep evaluation of the 2x2 matrix (Table 2), showing that 16.5% of travelers aware of ASF still transported pork products, is a standout finding that informs future biosecurity communication strategies.
Minor Recommendations for Final Polish
- Figures 1 and 2 Justification
I acknowledge and accept the authors' justification for retaining Figures 1 and 2 in the main text. The provided citations (King et al., 2020; Rosli, 2018; Hasanica et al., 2020) sufficiently demonstrate the precedent for including awareness materials as methodological illustrations in social science-related health research. No further movement of these figures is required.
- Underreporting and Legally Sensitive Behavior
While the authors have expanded their discussion on limitations, it should be more explicitly stated that the 9.7% transport prevalence is likely a conservative lower bound. Given that transporting pork products can be legally sensitive or restricted, respondents may underreport this behavior despite the survey's anonymity. A single additional sentence in the Discussion section (Section 4) clarifying this "lower-bound" perspective would add beneficial nuance.
- Sea Route Surveillance Gap
The authors noted that port authorities declined participation. This is a significant finding in itself. I recommend the authors explicitly frame this in the Conclusion (Section 5) as a specific surveillance gap that regional policy must address, given that 2.5 million passengers arrived by sea in 2025.
- Minor Formatting Clarification
Table 1 Consistency: The authors stated they reorganized the table in descending numerical order for ease of interpretation. Please ensure that Q4 (Country from) maintains this order consistently across all listed countries, including those with 0.0% values, to ensure visual clarity.
Author Response
The authors have demonstrated a high level of transparency and effort in addressing the substantial conceptual and methodological concerns raised in the first round of review. By reframing the study as "behavioral evidence" rather than a formal "risk assessment," the manuscript now aligns its claims with its actual analytical output. The addition of detailed statistical methods and the completion of administrative metadata significantly improve the paper's scientific rigor.
Response:
Dear reviewer,
We authors greatly appreciate the work you did in the first and second rounds.
Major revisions often mean significant improvements to the work. Having a constructive outside perspective, such as yours, can only improve the way we want to communicate our work to readers. For this reason, as the corresponding author and also on behalf of the other authors, I would like to thank you very much.
Your suggestions have been effectively implemented and, truly, it is now on another level.
General Evaluation
The revised manuscript is significantly strengthened. The authors successfully shifted the focus toward the behavioral interface of African Swine Fever (ASF) introduction, which is a critical, often neglected component of transboundary animal disease (TAD) surveillance. The inclusion of specific epidemiological context—such as the 2023 genotype II introduction in Nuoro province—provides necessary urgency and justification for the study
Response: thank you very much, it's also thanks to your suggestions!
Strengths of the Revised Version
- Reframing of Scope: The change in the title and abstract to emphasize "behavioral evidence" accurately reflects the nature of the data provided
Response: we agree that this approach is more correct and in line with our results.
- Methodological Transparency: The addition of Sections 2.3 and 2.4, specifying the use of R software (Version 4.5.2) and appropriate non-parametric tests (Kruskal-Wallis, Mann-Whitney), resolves the previous lack of reproducibility.
- Knowledge vs. Action Paradox: The deep evaluation of the 2x2 matrix (Table 2), showing that 16.5% of travelers aware of ASF still transported pork products, is a standout finding that informs future biosecurity communication strategies.
Minor Recommendations for Final Polish
- Figures 1 and 2 Justification
I acknowledge and accept the authors' justification for retaining Figures 1 and 2 in the main text. The provided citations (King et al., 2020; Rosli, 2018; Hasanica et al., 2020) sufficiently demonstrate the precedent for including awareness materials as methodological illustrations in social science-related health research. No further movement of these figures is required.
Response: thank you very much for your understanding. The sociologist colleagues who worked on the posters put a lot of effort into making them, and we like the fact that they are being recognized by publishing them in the work. This may also help future research in structuring the graphics.
- Underreporting and Legally Sensitive Behavior
While the authors have expanded their discussion on limitations, it should be more explicitly stated that the 9.7% transport prevalence is likely a conservative lower bound. Given that transporting pork products can be legally sensitive or restricted, respondents may underreport this behavior despite the survey's anonymity. A single additional sentence in the Discussion section (Section 4) clarifying this "lower-bound" perspective would add beneficial nuance.
Response: we added the phrase "It should be noted that this proportion is likely a conservative lower-bound estimate, as the transport of pork products may be perceived by travelers as legally sensitive or restricted, potentially leading to underreporting despite the anonymous and voluntary nature of the survey." in discussion.
- Sea Route Surveillance Gap
The authors noted that port authorities declined participation. This is a significant finding in itself. I recommend the authors explicitly frame this in the Conclusion (Section 5) as a specific surveillance gap that regional policy must address, given that 2.5 million passengers arrived by sea in 2025.
Response: we agree and thank for this suggestions. the phrase "In addition, the absence of port authority participation should be explicitly recognized as a critical surveillance gap along sea travel routes, which warrants targeted policy attention, particularly in light of the approximately 2.5 million passengers who arrived in Sardinia by sea in 2025." have been added in conclusion section.
- Minor Formatting Clarification
Table 1 Consistency: The authors stated they reorganized the table in descending numerical order for ease of interpretation. Please ensure that Q4 (Country from) maintains this order consistently across all listed countries, including those with 0.0% values, to ensure visual clarity.
Response: checked, thank you!
We would like to specify that the entire manuscript has been revised by the MDPI english editing service, please let us know if the revised version is fine for you about the language or if you suggests a second revision by the MDPI english editing service.
