Review for 10.1186/s12876-022-02174-4 (2022)

Title: Fecal indicator bacteria along multiple environmental exposure pathways (water, food,
and soil) and intestinal parasites among children in the rural northwest Ethiopia
Version: 1 Date: 01 Dec 2021
Reviewer's report:
This manuscript explores multiple risk factors associated with increased risk for enteric
infections in children living in Ethiopia. The authors utilized both qualitative and quantitative
data in the forms of questionnaires, and detection of Escherichia coli as a indicator of fecal
contamination and stool ova examination by wet mount and Kato-Katz techniques to conduct
their study, respectively. Parasitic infections were evaluated in the study participants and the
adjusted odds ratios of contributing factors were determined. The authors conclude their study
with recommendations that would improve the quality of living and reduce rates of enteric
infection.
General comments:
The authors have designed an extensive study that examines risk factors associated with enteric
infections, with significant focus on parasitic agents of enteric disease. However, the manuscript
does not acknowledge viral or bacterial agents of enteric infection and the use of the phrase
“enteric infections” throughout the manuscript is inappropriate considering no efforts to detect
or identify other agents of enteric infections were made. Only in the Methods section, Sample
size determination paragraph (line 95) do the authors specify that enteric infections are used
to signify soil-transmitted helminthiasis. The authors should recognize that co-infection with
viral or bacterial pathogens are a confounding variable in their study, as diarrhea may not be
solely attributable to the parasitic ova identified in their study participants. My suggestion to the
authors would be to discuss this topic in their discussion or to adjust their manuscript accordingly
to reflect the focus on parasites.
I think that the figure included as supplemental material is well crafted and worthy to be included
as part of the manuscript as it summarizes the key findings of the study well. My suggestion
would be to not include the pie charts from Figures 2 and 3 if there is a limit to figures as pie
charts are not a particularly good method of displaying data visually. Furthermore, for each pie
chart the proportions do not exceed 5 at most and can be easily described in text in the Results
section.
English language editing and proof-reading is strongly advised if the authors wish to resubmit
this manuscript for publication. I noticed grammatical errors and areas within the manuscript
that sentence structure can be improved.
Specific comments:
Line 22 (Abstract): E. coli should be spelled out as the entire genus the first time it is included
in the manuscript. I’d suggest this as well for the title. I understand Escherichia coli is implied
and indicated in the acronyms section, but standard nomenclature rules should be followed.
Furthermore, it would prevent misunderstanding with Entamoeba coli, as it is a non-pathogenic
intestinal amoeba that can also be used as an indicator of fecal-contamination in water and foods.
Line 76 (Background): Clarification of the use of “human body envelope”. I presume the authors
are using the phrase in regards to the load of enteric pathogens entering the human body but this
is not commonly used in microbiological or medical literature to my knowledge.
Line 120 (Methods): How many drops of saline were placed on the slide for direct stool
examination if not 1 drop. Wet mount preparation is a standardized procedure and I believe
the methods can be further clarified and written more concisely to reflect that. My suggestion
to the authors would be to state that stool specimens were diluted with saline as necessary for
direct examination as opposed to the vague description used in this section. I would also advise
the same for the following sentences regarding the Kato-Katz technique as well. Considering
numerous guidelines are published by the WHO and others in literature, the writing in the
Methods section for this procedure can be improved as its current state is rather convoluted.
Line 130 (Methods): How was the occurrence of childhood diarrheal diseases in a 2 week period
measured and documented. There is explanation of this on line 163-164; the authors should
either remove this sentence in line 130 or reorganize the Methods section appropriately.
Discussion: Considering the extensive data generated from this study that is presented in the
Results section, I believe that the Discussion section is lacking and can be considerably expanded
upon. As I mentioned in my General Comments, the authors can explore the limitations of the
study in the Discussion in relation to the lack of identification of viral and bacterial enteric
agents. In addition, I wonder if the authors investigated whether the inherent shortcomings of the
Kato-Katz technique in relation to variation in ova distribution in stool and reading of slides may
have affected the ova quantification results. I did not see any statistical analyses for variation
and error in the results.
Figure 1: The legend included in the figure does not provide any useful information and is
inappropriately labeled along with the Y axis. My suggestion would be for the Y axis to be
labeled as "Proportion of samples" and if the authors wish to include a legend, they can represent
"Positive" and "Negative" as that reflects the bars better compared to "Yes" and "No".