Prevalence and Risk Analysis of Human Geohelminths in Rural Communities of Ilalo, Ecuador

Round 1

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

Abstract:

The conclusion about the risk factors needs to better highlight what would be the professional activity with fruit farming and pig farming. Note the passage ‘The estimated risk factors were: pig farming (OR: 4.16; 95 % CI: 2.34, 7.42) as well as vegetable and fruit growing (OR: 11.66; 95 % CI: 4.32, 41.08)’.

Key words:

remove the term “Ilaló”.

Introduction:

The introduction is well founded, however I question the emphasis given to COVID-19, I believe that such an inference is unnecessary, since it was not considered as a risk factor in the work. There is also no mention of other STH, such as Strongyloides stercoralis.

Methods:

Remove the information ‘used ivermectin as an auxiliary in SARS-CoV-2 coronavirus’ since it is common knowledge that this drug is not for prophylaxis and treatment of COVID-19 infection.

Figure 1 is of low resolution and it is not possible to visualise the locations precisely.

I understand that the main aim of the study is to find STH, but couldn't the methods used have detected protozoa or Strongyloides stercoralis larvae? If they did identify them, were the data discarded?

 

Results:

Were 73 patients positive in at least one or all of the samples? What about the frequency of positivity between the different parasitological methods used? This needs to be well detailed.

Discussion:

The discussion is coherent and well constructed.

 

Conclusion:

The study concludes that prevalence was reduced by measures adopted in the pandemic period, but the work does not have sufficient evidence for such a statement.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

This study deals with estimation of the prevalence and intensity of soil transmitted helminthiases among human population in rural communities in the Ilaló Region (Ecuador) in post-coronavirus pandemic period. Soil-transmitted helminth (STH) infections are among the most common infections worldwide. Human infection with soil-transmitted helminths remains a serious problem in tropical and subtropical areas. The study of Ecuadorian colleagues is significant due to the importance of control, treatment and preventing dangerous human STH helminthiases. The authors identified a number of STH nematode species and conducted a statistical analysis of the data. The manuscript fits into aims and scope of the journal Parasitologia and can be published, but I have some minor remarks, which will undoubtedly improve this article.

 

1. Very high-quality Introduction, Materials, Results and Discussion sections. But the Conclusion is too short and says nothing about your important results obtained in your study, the dependencies of human infection. This needs to be corrected and the conclusion needs to be expanded somewhat.

2. The title from Fig. 2 must be removed. It is already in the caption to Fig. 2

3. line 18. The total number of those examined persons (320) is already in the previous sentence. Here it is enough to give only the number of infected persons – 73. The same applies to the line 161. Or it needs to be fixed like this: “A total of 320 from 2432 people …”

4. Line 19 – Please, Give the generic name in full here - Ascaris lumbricoides.

5. Section 2.4. Ethical Considerations (lines 149-157) – This needs to be removed here. Bioethics should be at the end of the article, where there is a corresponding section.

6. In Table 2, it is advisable to provide the Latin names of helminths in full.

7. All parasites in your study are helminths (even more narrowly - nematodes). Therefore, the title of Table 3 should be changed: “Classification of helminthiases by intensity of infection.”

8. According ICZN (International Code of Zoological Nomenclature), at the first mention of species and genera in the article text, its full Latin name with the author and year of description should be given; in relation all species of living organisms (for example, lines 29,30 – Ascaris lumbricoides Linnaeus, 1758, etc.). Line 365 - Ascaris suum (Goeze, 1782).

9. The article must be formatted in accordance with the MDPI journal rules. Only the first letters of words should be capitalized in the article title. All words in subsection titles must be written in capital letters. For example, 2.2. Selection of Samples and Parasitological Methods

10. The Authors incorrectly format references to other works in the article. The whole text must be checked. For example, Lines 279,280 - … of Shahbaznejad et al. [14] and Chachar et al. [27] … Lines 328, 340 – …Ercumen et al. [43]…, … by Vaz Nery et al. [47] … There is no need to insert the year here, the number in the list of references is enough.

Lines 303,307 – … Grimes et al. [33] in 2014 …, … by Strunz et al. [34] in 2014…

11. As a suggestion. Tables 4 and 5 are complex and cumbersome to understand. Can this material be presented in the form of diagrams and graphs?

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

NOTES FOR AUTHORS

 

General notes:

Manuscript has greately improved since last version. Some minor but important improvements yet must be done. Across the manuscript you insist in the causality of a “lower” prevalence of STH because of COVID19 measures. This is interesting hypothesis but your data do not permit such conclusions. This is because you are not demonstrating such causality. Causality would require at least a longitudinal study (not a cross sectional like this) where you, by studying the same population along several years (before and after pandemics) demonstrate that the change occurred and that change was explained mainly by the improvement of measures.  This information is lacking, so this conclusions can not be made. You can only suggest that lower prevalences in comparison with the general findings in all other studies in Ecuador could be related to this situation.  You must reword or eliminate every line across the manuscript where you suggest that causality in a form of “demonstration”.  On the other hand, your results can be a good starting point of comparison if you repeat this study some years from now. Why, because, SARS-COV2 measures would have been more relaxed (people are losing those cautions) and, in such scenario, you would have better information to hypothesize such causality, if you study the same population.

Statistical analysis have been improved. Some suggestions on clarification about variables are made. It would be very important to add the standardized questionnaire so readers can see directly how information was gathered. This is important because of repeatability or further improvement in studies that you or colleagues will make in the future.

 

In next lines, I add those last suggestions to get a final improved paper.

 

Abstract

Line 22: Please eliminate  the Word “due”  because you are not demonstrating a direct causality between reduction of parasites and COVID19 measures, it is a possibility but your data do not permit that conclusion.

Keywords: Eliminate Coronavirus, you could add another word more related to your work.

 

Introduction

Writing is very good. My only suggestion here is the next: please make less emphasis in SARS-COV2 relations to parasitic diseases (reduce this paragraph) but add more information contextualizing the lack of information on STH infections in the regions you studied.  

 

Materials and methods

General:  Somehwere in the methods you should state that you managed the patient information anonymously as ethics committees demand.  As a suggestion and if it is within your possibilities, adding an annex with the questionnaire and explanation of how do  you defined your predictor variables would be excellent.

Line 89. Just add a reference for the source of information on the total population. Here also add the software you used for calculation (for example openEpi, or the software you used).

Line  96-97.  “Not taking an antiparasitic drug” sounds more like an exclusion criteria, put this as an exclusion criteria like this “Exclussion criteria: Having taken antiparasitic drugs…etc, in the last six months,  Inclussion criteria: the other you already have.

 

Line 100.  Can´t read the words inside the map, they must appear larger so we can read it.

 

Line 133: pleas add detail on the definition of “type of infection” and “Types of mixed infection” in this part.

 

Line 140:  add the reference of the WHO guidelines.

Lines 149-157: If you have a number of resolution of your ethics committee for this research, this is the place to add it.

 

Line 173.  Some variables are in deed composed of two types: eg.  Handwashing has Handwashing yes-no, and Handwashing with levels “after using bathroom, once a day and several times a day”, It would be better separate them: handwashing (with levels yes-no)   and Frequency of handwashing. The same for Show use, and animal Farming.  Animal Farming has a problem because as shown in the table it seems categories are yes-no and pigs, this has no sense. So , I would suggest divide it in the table  Animal Farming (with levels yes-no) and Type of Animal Farming (with levels Pigs (and pleas add the others because they are not shown in the table   I suppose is Pigs, Beef, ? what others?).

Line 199:  “Figure 2: Positive and negative STH cases by location in the Ilaló Strip, Pichincha, Ecuador.”

Line 219-222: Interpretationis like this. An OR <1  (and in our case, very low) indicates that  one is a protective factor.. OR>>1 indicates that that factor Is associated as a factor that favours the infection. OR means “association” not risk nor causality.

 

 

 

 

Discussion

LINES 311-312:  eliminate the word “due” because this imply you have demonstrated that STH had a reduction because of COVID-19 hygiene measures, your study design do not permit such a conclusion. You can suggest a possible relationship.

Line 379-385  You could use this part to acknowledge that a a limitation that you had to make a direct relationship between covid-19 measures and reduction of STH is that you did a cross sectional study and for such a conclusion longitudinal studies where follow up of patients is made to see that reduction in the same population, but you did not have previous data on STHs for the same regions of Ilalló.

 

In general, discussion is very well written, pleas be sure along all manuscript.

 

I did not find errors in bibliography.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

 

The article describes a study conducted in Ilaló, Pichincha, Ecuador, focusing on the prevalence of soil-transmitted helminthiases (STH) and associated risk factors in the post-SARS-CoV-2 pandemic period. STH are the most common helminth infections globally, often linked to poor sanitation and poverty. The study aimed to estimate the prevalence of STH in a rural population, identify the helminth species present, and assess risk factors, including pig farming and vegetable/fruit cultivation. A total of 320 individuals were tested using three diagnostic methods, and 22.81% were found to be infected. The most frequent parasite was Ascaris lumbricoides, and significant risk factors were identified. The findings contribute important post-pandemic insights into STH prevalence and control in the region.

Introduction:

1.       The statement that the SARS-CoV-2 pandemic increased the risk of STH infections ("increasing the risk of contracting STH due to the precarious conditions in which they are carried out") requires support from specific data or studies. Otherwise, it remains speculative.

2.       The introduction does not consider the potential impact of existing STH control programs (e.g., mass deworming programs) on the reduction of infection rates in the region.

3.       It is mentioned that the SARS-CoV-2 pandemic caused a lack of resources and personnel for combating STH, but no quantitative data or examples from the region are provided to support this claim.

4.       It is mentioned that self-medication with ivermectin worsened the health of residents, but there are no details provided regarding the number of cases, complications, or the exact mechanisms of its impact on health.

Results:

The section on "Results" lacks clear statistical justification for the analyses conducted. Although significant differences are mentioned in both bivariate and multivariate analyses, the specific statistical methods used (e.g., chi-square test, logistic regression) are not detailed, making it difficult to assess the validity of the findings. Furthermore, the p-values for these analyses are not provided, which hinders the evaluation of their statistical significance. Additionally, the data regarding the distribution of infection intensity (e.g., "mild," "moderate," "higher") are vague. There is no clear definition of the criteria used to classify the intensity of infection, and the results are presented without confidence intervals for the proportions of infection intensities, which further limits the interpretability of the findings. To improve the clarity and rigor of the analysis, the authors should include the statistical methods applied, report p-values for all relevant analyses, and provide more precise definitions for the categories of infection intensity along with the corresponding confidence intervals.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (New Reviewer)

Comments and Suggestions for Authors

Dear authors,

Congratulations on your work, which will contribute to knowledge about parasitic diseases. All corrections pointed out in December 2024 have been accepted.

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

After a considerable amount of revision, the Ecuadorian authors' article is now more structured and logical. The authors have implemented all the reviewer's suggestions, and the article is ready for publication.

Reviewer 3 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

All changes were met and the paper have the sufficient quality for publication.  Thank you for sharing your work. 

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors presented the confirmed links between soil-transmitted helminthiasis and quarantines due to the COVID-19 pandemic in their manuscript. Although the research is considerably valuable and provides plenty of new information for understanding parasitic diseases in people living in rural areas of Ecuador, it cannot be published in its present form due to methodological shortcomings.

Major reflection

The authors examined the samples using three methods (Mini Flotac, McMaster, Kato-Katz) and determined the prevalence and mean intensity. The calculation of mean intensity is detailed in Lines 82-85. Since the sensitivity of the methods used differs significantly (Levecke et al. 2011; Coulibaly et al. 2016) no mean can be calculated. Since there are very few standardized methods in parasitology, the above mentioned metrics can be determined by several accepted methods. Since the sensitivity of each test method can vary considerably, it is almost impossible to compare the results obtained by those. Therefore, the results of the mean intensity are misleading and cannot be applied in the present study. It would have been advantageous if the authors had chosen the most sensitive method to calculate the average intensity.

The description of the statistical methods needs to be detailed and clarified. The methodology presented in Lines 90-92 is incomprehensible. In the study, only one dependent variable (STH) was. It was incorrectly classified as an independent variable. Furthermore, it is impossible to interpret what exactly the '... the dependent variables were the components or 90 variables...' expression means. Another problem is the determination of relationships between dependent and independent variables. Although it is not discussed in the chapter Material and Methods, the authors indicate that bivariate and multivariate analysis were used in the Results. In their study, the authors did not create a multivariate model but a multivariable model. The multivariate approach is used for the analysis with more than one outcome (e.g., repeated measures) and multiple independent variables. The multivariable model is used for the analysis with one outcome (dependent) and multiple independent (predictor or explanatory) variables (Hidalgo and Goodman, 2013).

In binary analysis, the relationships between dependent and independent variables demonstrated which explanatory variables significantly affect STH infection. In the so-called 'multivariate analysis', the authors examined these variables and obtained results consistent with those of the previous approach. In fact, they were doing a binary regression because their dependent variable (STH) was binary. The two methods they used were completely identical. The difference was only in the number of explanatory variables. As a result, the use of so-called 'multivariate analysis' is unnecessary.

Although the title refers to the effects of the COVID-19 pandemic, it is unclear from the manuscript to what extent the results obtained were affected by the quarantines imposed due to the pandemic. The text does not reference what kind of STH infection was typical in the study area before the COVID-19 pandemic. As a result, the impact of quarantine cannot be estimated.

Some minor reflection

Analyses have shown that A. lumbricoides infection was closely related to pig farming. Since humans' and pigs' roundworms (A. lumbricoides and A. suum) can cross-infect the two hosts, I recommend using the term Ascaris spp.

Line 12. The helminths are not infections. They can be just the causative agents of the infections.

Line 15.The parasitic load could be investigated only by autopsy. With the methods used in the study, a conclusion about parasites is possible only in cases where there is a strong correlation between egg count and worm count. However, there is no reference to this in the material.

Line 17, 75, 84. There needs to be consistent use of methods' marking.

Line 72-84. Detail the three parasitological methods. (sample size, specific gravity of flotation fluid, number of investigated subsamples, etc.)

Line 76. What do SF2 and SF5 mean?

Line 79. Insert reference.

Line 79-82. What does HPG mean?

Line 85-93. Which r-cran packages were used for statistical analysis?

Line 144 (Table 2) Please, avoid the use of Spanish language in the text.

Because of the above, I suggest the authors correctly rethink the manuscript containing valuable results and resubmit it for review.

References

Coulibaly et al. Comparison of sensitivity and faecal egg counts of Mini-FLOTAC using fixed stool samples and Kato-Katz technique for the diagnosis of Schistosoma mansoni and soil-transmitted helminths. Acta Trop. 2016 Dec;164:107-116.

Hidalgo B, Goodman M. Multivariate or multivariable regression? Am J Public Health. 2013 Jan;103(1):39-40.

Levecke et al. A comparison of the sensitivity and fecal egg counts of the McMaster egg counting and Kato-Katz thick smear methods for soil-transmitted helminths. PLoS Negl Trop Dis. 2011 Jun;5(6):e1201.

Miller LA, et al. Ascariasis in humans and pigs on small-scale farms, Maine, USA, 2010-2013. Emerg Infect Dis. 2015 Feb;21(2):332-4.

Comments on the Quality of English Language

The English of the manuscript is clear and acceptable after moderate correction.

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors. Information derived from this effort is valuable and interesting as is related to STH infections, part of the neglected tropical diseases. In my opinion, the paper has good potential to be published once improved in some key points that I proceed to detail. 

 

Title: “post-covid-19 pandemic” seems to be unnecesary here, since there are no data analysis derived from any covid-19 issue performed by you here. Prevalence calculations must be proved or title must change to “Frequency” instead of prevalence. (this is further explained later in the comments).

 Abstract

Lines 13-14.  Again, as you don´t have previous covid-19 data from ilalo communities presented here and compared to your data, this lines don´t make a contribution here.  The same for lines 21-22.

 

Introduction

As in title and abstract, references to covid in this paper as an important factor that you are to prove or discuss, do not contribute because you are not analyzing directy any COVID-19 efects on the STH prevalences or frequencies.

On the other hand, Good justification for this study, which is the lack of recent data on STH epidemiology from the Ilalo region Ecuador and ther possible associations with risk factors is not mentioned.

 

Methods

Overall comments on methods:

 

On the exclusión criteria (line 65-67):  it is unnecessary to write an exlusion criterion that states “individuals who did not meet the inclusión criterio”, Consider changing “taking antiparasitic drug within the last 6 months”  to exclusión criteria.

2.3 statistical analysis

Statistical analyisis description must be thoroughly improved. There is insuficient detail on how the sample size was calculated in order to estimate a real “Prevalence”: total population must be mentioned here (not only in the figure 1), and the elements of sample size calculation (tota population size, anticipated frequency or, if unkwnon, the use of 50%, absolute precisión (usually 5%), and a factor number because of the design effect (when absolute random sampling is not possible).  Anticipated prevalence come from previous similar studies in the same región, are there previous studies giving a frequency measure of intestinal parasites?, if don´t, you should use 50% as anticipated prevalence as one of the parameters to calculate the sample size.  It seems estimations of sample size indicate that you should have used more than 330 participants to determine “Prevalence”, an epidemiologist could help you corroborate that.

 

Refer to table 1 in methods so readers get to know what are the categorical variables.

Line 90 is confusing. What would it mean “dependent variables were the components or  variables”. It seems your dependent variables are the next events: 1.  presence/abscense of each helminth species (A. lumbricoides, T. trichura, and Hookworms),  2. Presence/absence of one, two or three parasites. Presence or absence of each parasite combination, and intensity of infection (also categorical).

With the categorical variables you performed  first a bivariate analysisi and latter a multinomial or multivariate logistic regresión analysis? 

that you don´t mention in the statistic analysis section in the methods. 

in the bivariate and multivariate analysis, what was the outcome or dependent variable used?  "sth infection in general"? or A. lumbricoides infection? or Trichuris trichiura infection?  both parasites without hookworms? hookworms included?  this is not clear )(line 157). 

How did you calculate the odds ratio?  Did you use a chi-square analysis to get a p-value in order to determine the significance of the possible associations?

In general, this section of “statistical analysis” must be greatly improved, better details must be provided, so it is very clear for the readers what are your variables and statistical methods.

Comments on the Quality of English Language

I´m not a native english speaker, but I consider I have a good level.  I found no major issues concerning to english writing quality. Table 2 has some spanish words left to be translated, other minor issues with the language are in the comments. A minor revision of english grammar by the editors should be sufficient.