Review Reports - Red Deer (<i>Cervus elaphus</i>) Fascioloidosis: From Liver Pathology to Regeneration

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript investigates hepatic lesions associated with Fascioloides magna infection in free-ranging red deer following population-level anthelmintic treatment. By combining gross pathology with histological evaluation, the authors describe a spectrum of changes from migratory tracts and pseudocysts to degrading pseudocysts and nodular reparative lesions. The topic is relevant for wildlife parasitology and disease management, particularly given the increasing use of medicated feed in endemic regions. The focus on post-treatment hepatic remodeling under field conditions is conceptually interesting and adds potentially valuable descriptive data. However, there are still some issues that need to be clarified.

Abstract：

Line 14: The phrase “allochthonous parasite” is missing an article.

Line 15: “finals hosts” is a typographical error and should read “final hosts.” When listing categories, commas should be used (i.e., “definitive, aberrant, and dead-end”).

Line 16: “program” should be pluralized to “programs.”

Lines 17–18: “oral treated” is grammatically incorrect. A comma is required after “In this study.” “during 5 consecutive days” should be revised to “for 5 consecutive days.”

Line 19: “a destroyed pseudocysts” contains a singular–plural inconsistency. “different amount” should be revised to “different amounts.”

Lines 21–22: The phrase “average number” requires the definite article “the.” The formatting of the content within parentheses should be standardized.

Line 25: “average 7.99” is missing the preposition “of.”

Line 27: “fibrous connective” should read “fibrous connective tissue.” The term “parenchyma” appears redundantly.

Line 30: The expression “bound with” is inappropriate and should be revised.

Lines 32–33: “potential” requires the definite article “the.” “in case of” should be revised to “in cases of.”

Introduction：

Lines 40–42: “juvenile fluke” shows a singular–plural inconsistency.

Lines 42–46: Consider dividing this sentence into two or more sentences to improve clarity.

Line 49: There is a singular–plural inconsistency.

Lines 64–66: This sentence contains multiple issues related to tense and word choice and should be thoroughly revised.

Materials and Methods：

Section 2.1: Please clarify how the authors determined whether the culled deer had previously undergone treatment.

Sections 2.2 and 2.3: Was a quantifiable evaluation system or scoring method applied? If so, please describe it in detail.

Results：

Line 110: Please clarify what “P = 75%” represents.

Line 111: “total 600” should be revised to “a total of 600.”

Lines 113–114: Even if there is only one table in the manuscript, it should be labeled as “Table 1.”

Line 154: Please clarify the basis for the numbering sequence (e.g., 3.3.3).

Discussion：

This section is generally stronger than the preceding sections; however, several minor issues remain.

Such as：Lines 179–181: “at certain point” should be revised to “at a certain point.”

Comments on the Quality of English Language

Please carefully review the manuscript and thoroughly revise the language throughout.

Author Response

Reviewer 1

Comments and Suggestions for Authors

Thank you for positive and constructive comments.

Abstract：

Line 14: The phrase “allochthonous parasite” is missing an article.

Inserted.

Line 15: “finals hosts” is a typographical error and should read “final hosts.” When listing categories, commas should be used (i.e., “definitive, aberrant, and dead-end”).

Thank you. This is corrected in the text.

Line 16: “program” should be pluralized to “programs.”

Thank you. This is corrected in the text.

Lines 17–18: “oral treated” is grammatically incorrect. A comma is required after “In this study.” “during 5 consecutive days” should be revised to “for 5 consecutive days.”

I was not able to find term ‘’oral’’ in the text, and I agree that is incorrect term. Later in the text you may find we already used term perorally, as it is a question of the route of administration and place of resorption. Second part of the comment is accepted and text is revised accordingly.

Line 19: “a destroyed pseudocysts” contains a singular–plural inconsistency. “different amount” should be revised to “different amounts.”

Corrected.

Lines 21–22: The phrase “average number” requires the definite article “the.” The formatting of the content within parentheses should be standardized.

Corrected.

Line 25: “average 7.99” is missing the preposition “of.”

Corrected.

Line 27: “fibrous connective” should read “fibrous connective tissue.” The term “parenchyma” appears redundantly.

Thank you. Corrected.

Line 30: The expression “bound with” is inappropriate and should be revised.

Corrected and modified to ‘’surrounded’’.

Lines 32–33: “potential” requires the definite article “the.” “in case of” should be revised to “in cases of.”

Corrected.

Introduction：

Lines 40–42: “juvenile fluke” shows a singular–plural inconsistency.

Corrected.

Lines 42–46: Consider dividing this sentence into two or more sentences to improve clarity.

Done.

Line 49: There is a singular–plural inconsistency.

Corrected.

Lines 64–66: This sentence contains multiple issues related to tense and word choice and should be thoroughly revised.

Done.

Materials and Methods：

Section 2.1: Please clarify how the authors determined whether the culled deer had previously undergone treatment.

We do not claim that each animal has undergone the treatment. It is treatment on a population level with potential effect of herd hierarchy, deer migration and the fact that some animals probably did not visit feeding places at that time. However, since animals reside in these areas at that time and food was provided in accordance with calculated population size, we expect that at least majority of them consumed the medicated feed.

Sections 2.2 and 2.3: Was a quantifiable evaluation system or scoring method applied? If so, please describe it in detail.

There is no existing scoring method. We could only classify observed lesions or parasites and calculate them.

Results：

Line 110: Please clarify what “P = 75%” represents.

It represents percentage of positive animals (after negative and cured livers were excluded, there were 102 positive livers). However, this was deleted in accordance with the reviewer 2 comment.

Line 111: “total 600” should be revised to “a total of 600.”

Corrected.

Lines 113–114: Even if there is only one table in the manuscript, it should be labeled as “Table 1.”

Done.

Line 154: Please clarify the basis for the numbering sequence (e.g., 3.3.3).

Thank you for noticing. This is a mistake.

Discussion：

This section is generally stronger than the preceding sections; however, several minor issues remain.

Such as：Lines 179–181: “at certain point” should be revised to “at a certain point.”

Thank you. Done.

Comments on the Quality of English Language

Please carefully review the manuscript and thoroughly revise the language throughout.

English was originally corrected by certified agency (proof provided).

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript describes pathological lesions in red deer livers infected with Fascioloides magna following albendazole treatment, focusing on the degradation of pseudocysts and subsequent regenerative changes in liver tissue. The topic is relevant to veterinary pathology and wildlife parasitology, and the authors present macroscopic and histological observations from 136 livers collected during the hunting season.

However, the manuscript is largely descriptive and suffers from several methodological and interpretational limitations. In particular, the study design, sampling strategy, statistical analysis, and interpretation of liver regeneration require clarification or revision. Additionally, the manuscript would benefit from language editing and improved organization. Therefore, substantial revisions are required before the manuscript can be considered for publication. Here are some comments:

Major Comments

1. Study design and objectives

The introduction does not clearly define the primary objective or hypothesis of the study. While the manuscript appears to focus on pathological changes following treatment and possible liver regeneration, this aim should be clearly stated at the end of the introduction.

2. Sampling strategy and prevalence interpretation

The manuscript states that 600 red deer were shot in the region, but only 136 livers were examined using a convenience sampling approach. Because of this sampling method, the infection rate reported in the manuscript cannot be interpreted as prevalence.

Furthermore, the statement in the Results section that 15 out of 136 livers were negative (P = 75%) appears incorrect and should be carefully checked.

The authors should clarify the sampling approach and avoid drawing epidemiological conclusions.

3. Lack of statistical analysis

The results are presented only as averages without measures of variability (e.g., standard deviation or confidence intervals). No statistical comparisons between sampling locations or lesion types are provided.

Even in descriptive pathological studies, basic statistical descriptors should be included.

4. Interpretation of liver regeneration

The manuscript repeatedly suggests that the observed lesions demonstrate liver regeneration. However, the histological findings mainly describe fibrosis, pseudolobule formation, and regenerative nodules, which may reflect reparative processes rather than true regeneration.

The conclusions regarding liver regeneration should therefore be moderated, and the distinction between regeneration and repair should be clarified.

5. Evidence for treatment success

The manuscript assumes that albendazole treatment was successful, but no data are provided to demonstrate treatment efficacy. The presence of degraded flukes does not necessarily confirm treatment success at the population level.

The authors should either provide supporting evidence or avoid strong claims regarding treatment efficacy.

Minor Comments

The manuscript requires careful English language editing to improve clarity and grammar.
Some terminology should be standardized throughout the manuscript (e.g., definitive host vs. final host).
Figures require clearer labeling and consistent numbering. For example, Figure 4 panels appear to be labeled inconsistently (e.g., “1a, 1b”).
Magnification or scale bars should be included in histological images.
Table formatting should be improved, and measures of variation should be added.
Several typographical errors should be corrected (e.g., “approximal thickness” should be “approximate thickness”).

Author Response

Reviewer 2

Comments and Suggestions for Authors

The manuscript describes pathological lesions in red deer livers infected with Fascioloides magna following albendazole treatment, focusing on the degradation of pseudocysts and subsequent regenerative changes in liver tissue. The topic is relevant to veterinary pathology and wildlife parasitology, and the authors present macroscopic and histological observations from 136 livers collected during the hunting season.

Major Comments

Study design and objectives

Thank you. Done.

Sampling strategy and prevalence interpretation

I agree. Prevalence is removed from the text.

Furthermore, the statement in the Results section that 15 out of 136 livers were negative (P = 75%) appears incorrect and should be carefully checked.

It is correct number, since it shows prevalence of positive animals. When negative and cured livers were excluded, there were 102 positive livers, which is 75% out of 136. However, this is removed from the text.

The authors should clarify the sampling approach and avoid drawing epidemiological conclusions.

We did not made any epidemiological conclusions. Sampling approach was already clarified, as it was the only possible one. Treatment is done in voluntary agreement with hunting associations, it is not directed by the state. Therefore, we can’t force them to collect samples.

Lack of statistical analysis

Even in descriptive pathological studies, basic statistical descriptors should be included.

Inserted.

Interpretation of liver regeneration

This was already written in the last paragraph of the Discussion. And I agree with the reviewer fully. However, this is matter of original translation and use of terms, but pathologists in the team (of which two are Diplomates of the ECVP) state that it is usual to use term regeneration. To further clarify this discrepancy in terms, we have originally wrote one sentence in the Discussion part.

The conclusions regarding liver regeneration should therefore be moderated, and the distinction between regeneration and repair should be clarified.

As stated above.

Evidence for treatment success

This is a misunderstanding. What we meant is that after successful treatment one can find destroyed pseudocysts. In this article we did not evaluated treatment efficacy on the population level, mainly due to the bias caused by sampling method. We rephrased this in the text.

The authors should either provide supporting evidence or avoid strong claims regarding treatment efficacy.

As said above.

Minor Comments

The manuscript requires careful English language editing to improve clarity and grammar.

English language was already checked by certified agency (proof provided).

Some terminology should be standardized throughout the manuscript (e.g., definitive host vs. final host).

Done.

Figures require clearer labeling and consistent numbering. For example, Figure 4 panels appear to be labeled inconsistently (e.g., “1a, 1b”).

Corrected.

Magnification or scale bars should be included in histological images.

It is already on the images.

Table formatting should be improved, and measures of variation should be added.

Several typographical errors should be corrected (e.g., “approximal thickness” should be “approximate thickness”).

Done.

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript I was assigned is really interesting!

It focuses an ancient parasitic disease that is extremely common in wild ruminants and cattle that share the same grazing area,teating it in a modern, extensive and excellent way.

While it is well known that this parasitic infestation causes serious liver damage, and we teach our students about the migration routes of the larvae and their scarring effects so they can recognise this disease macroscopically, no one has ever so well analysed these routes histologically in detail or their effects at different stages or the regenerative aspects associated with them.
The work is very well conducted and the methods are extremely appropriate, with excellent histological staining and descriptions. This helps to reinforce the already robust and interesting results.
The images are beautiful, and the discussion is very detailed.

Taking all of the above into account, I am think that teh manuscript could be suitable for publication following minor revisions. In fact, it is necessary to add a short conclusions chapter to summarise the observations and emphasise their value.

Author Response

Reviewer 3

Comments and Suggestions for Authors

The manuscript I was assigned is really interesting!

It focuses an ancient parasitic disease that is extremely common in wild ruminants and cattle that share the same grazing area,teating it in a modern, extensive and excellent way.

The work is very well conducted and the methods are extremely appropriate, with excellent histological staining and descriptions. This helps to reinforce the already robust and interesting results.

The images are beautiful, and the discussion is very detailed.

Thank you for very positive feedback and nice words.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors answered all my questions, the manuscript can be accepted.