PONE-D-21-27631

Knowledge, practices and perceptions of communities during a malaria larviciding randomized trial in the city of Yaoundé, Cameroon

PLOS ONE

Dear Dr. Antonio-Nkondjio,

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PLOS ONE

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Reviewers' comments:

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Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: No

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This paper describes a study on knowledge and practices relating to malaria control, in the light of an intervention – larvicidal treatment – in Yaoundé, Cameroon. The paper includes valuable data and important insights, which would add usefully to the scientific literature. However, at the moment insufficient detail is provided regarding the methodology and results to be confident in the validity of the findings.

The relationship between this manuscript and other related studies is not clear. In particular, the data included from 2017 appears to have been already published by Talipouo et al. 2019, but this is not made sufficiently clear in the manuscript.

The aims and questions/hypotheses to be tested in this paper need to be clearer. The objectives are described as to ‘evaluate people's knowledge and perception of the success of a pilot larviciding trial’. However, the results presented address several questions, including: the impact of the larvicidal intervention on LLIN use; the impact of the intervention on malaria/mosquito knowledge and practices; people’s perceptions of the intervention on mosquitoes and malaria cases; attitudes towards the intervention; and willingness to participate in larvicidal treatment. These are mostly presented as a comparison between intervention and non-intervention areas. If the aim of the paper was to assess how these metrics differ between the intervention and non-intervention areas, this should be stated clearly in the objectives and made clearer in the methodology. In the methodology make sure that it is clear which part of the study is being addressed by each part of the methods.

More detail is needed in the methodology and results in order to tell if findings are robust and meaningful. For example:

- A randomised control trial is mentioned in the title, but the processes of randomisation or assigning intervention and non-intervention areas are not explained. It appears that this control trial is described in Antonio-Nkondjio et al. 2021 (ref 30) but some detail is required here because it has important implications regarding whether the findings are robust, since it is plausible the findings could be explained by the method of selecting intervention and control areas.

- How were households selected for questionnaire administration in each cluster? Was this randomised? Were the same households visited in subsequent years? If so, this needs to be accounted for in the statistics. If not, this should be stated.

- Binary measures e.g. ‘good practice’ and ‘good knowledge’ – how were these defined, how were the questionnaire data turned into a binary outcome?

- How was the binary model constructed – what were the outcomes and explanatory variables? Was each assessed in a separate model?

- How were the qualitative data analysed? What measures were taken to ensure the robustness of the analyses?

- In the results, make sure it is clear what statistics have been used to generate the p-values indicated (for example line 220, line 231), and include test statistics. Check the wording for odds ratios – it should read ‘the odds of people having good knowledge was 2.64 times higher’ rather than people were 2.64 times more likely to be aware.

Supplementary material is mentioned but was not provided to the reviewer. The raw data and copies of the questionnaire and interview guides should be provided.

In addition the English writing needs improvement in places since there are quite a lot of minor grammatical errors.

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Reviewer #1: No

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PONE-D-21-27631R1Knowledge, practices and perceptions of communities during a malaria larviciding randomized trial in the city of Yaoundé, CameroonPLOS ONE

Dear Dr. Antonio-Nkondjio,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please revise the paper according to the reviewer's comments, especially on improving the clarity in the data and statistical analysis. 

Please submit your revised manuscript by Sep 22, 2022. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

Guangyu Tong

Academic Editor

PLOS ONE

Additional Editor Comments (if provided):

We invited field experts to review your paper. Please address the reviewer comments accordingly, especially the clarity in the data and analysis presented in this paper.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: (No Response)

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Partly

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: I Don't Know

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4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

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6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: 1. Addressing the hypothesis. Early, a hypothesis states a larviciding trial will improve intervention-area residing people’s knowledge and practices related to malaria and its vectors, and generate positive perceptions among them towards larviciding, when compared with people in non-intervention areas. Additionally, the study assessed whether larviciding impacted LLIN use.

In the discussion, it is concluded that people in intervention areas were more likely to know the mode of transmission and be aware of breeding habitats compared to people in non-intervention sites, and thus the aspect of ‘knowledge’ is suggested to have improved. However, looking at Table 4, it seems that the percentage of those with ‘good knowledge’ actually reduces over time in the intervention category (89.4% in 2017, 88.88% in 2019, and 87.5% in 2020), and is non linear in the non-intervention category (87.44% in 2017, 92.34% in 2019, and 88.48% in 2020). For full disclosure, I am not a quantitative researcher, and thus I may simply be missing the logic – but it is not clear to me how this translates into greater odds of people having ‘good knowledge’ following intervention than in areas where there was no intervention.

Furthermore, while the ‘knowledge’ portion of the hypothesis is addressed in the discussion, ‘good practices’ as described in the methods section (lines 159-163) to be assessed are not addressed apart from the component of bed-net usage (e.g. going to hospital, eliminating standing water, purchasing drugs from pharmacy). Looking at Table 4, it would seem that the percent of people engaging in self-reported ‘good practices’ as defined by the authors’ criteria (at least 3 practices) declined to zero in both non- and intervention areas. I think it's safe to assume this decline was not related to the intervention itself – in fact, given the very low baseline numbers, it is likely that other factors play a role (see next comment) – a line or two on this would add value in the Discussion (as has been done with the explanation for lowered bed net usage).

2. Terms: ‘poor’/‘bad’ practices. It feels crude to categorise people’s practices as either being ‘good’ or ‘poor’ (or ‘bad’) due to the many nuances which might account for ‘poor’ practices. People may not seek hospital treatment because they cannot afford it (or the transportation to get to it), or have had negative experiences in clinics before. Labelling them ‘poor’ implies ignorance or failure. Could authors state it as a limitation that the quantitative survey can’t account for the ‘why’, and that it may obscure these nuanced realities? Related to this, line 164 says participants with less than 3 ‘correct’ answers were considered to have poor practices. ‘Correct’ again implies wrongness. Can you describe this differently. For example: ‘people who reported engaging in less than three of these practices were considered to not be practicing effective malaria prevention, whether due to knowledge, capacity or other limitations’.

3. Describe intervention. Can you please describe the intervention in the Methods section? What did it entail, how did it work? Although seemingly described in previous publication, the context is important for this paper. Such a brief description could be included under the ‘Selection of intervention areas’ heading.

4. What are clusters? Under the new ‘selection of intervention areas’ section, the unit ‘clusters’ is used to describe where entomological data was collected. Can the authors define a ‘cluster’ (I assume it is a geographical unit)? Were ‘cluster pairs’ created based on any variable other than ‘biting densities’? This is important as differences in outcomes between paired intervention/non-intervention clusters could result from other variables like differences in socio-economic status or education level between clusters. If not, it should be listed as a limitation that other social, economic, and perhaps spatial/environmental variables were not considered when selecting for pairs of intervention/non-intervention clusters. I realise this comes from a previously published paper, but context is needed for readers to understand this one. From a quick look at Table 2, it seems that intervention areas might have been slightly wealthier? For instance, 79.9% of houses in intervention areas were ‘modern’ while 69.5% were modern in non-intervention areas. Similarly, a higher proportion of the population was university educated in intervention areas.

5. Community participation. It is not entirely clear what is meant by participation, or as is commonly used in the paper ‘adherence’ of community members to larviciding. If larviciding is done by external teams, how might communities ‘adhere’? Elsewhere, participants are said to ‘freely participate’. Can the authors describe how community members were expected to ‘participate’ or ‘adhere’ in the trial? This could perhaps be done in a description of what the trial actually entailed and how it worked (see above comment), with modifications made elsewhere as necessary for clarity.

6. Selection of participants. Can the authors describe more about the random selection of households for the survey? Was a population/address register used? Similarly, the paper does not state how participants for the focus groups selected although it is stated that they were selected to represent ‘different demographic groups’ (line 186). Can the authors say what demographic groups these were?

7. Qualitative data analysis. Collection of qualitative data is described, but analysis is not well described beyond transcription, and key findings summarised. Was thematic coding or analysis conducted? What is meat by ‘analysed at different levels’?

8. Demographic differences. Although some demographic data is given about participants in the survey, the analysis does not differentiate between different cohorts of people. Were there differences between women and men, those with higher levels of education and lower, or by house type? If such analyses were not performed, or outcomes not deemed significant enough to report, the authors should state as such. Or perhaps, indicate that future publications might explore these differences. Indeed, generic conclusions can mask over important differences in knowledge, practices (and capacity) and perceptions that may have significant implications for who is most affected by malaria transmission.

9. Quick clarifications. Line 86 – Sentence is not clear. What is meant by ‘the cost person’ as being ‘protected’? Perhaps the authors mean to say: The intervention is considered to be cost-effective, with costs per person being similar to those of LLIN use in urban settings’.

10. Long/confusing sentence. Line 107 – The sentence is long and confusing. I suggest rewording slightly (see below), and then removing the latter part of the sentence as the point about comparison between the intervention area and the non-intervention area is made in the next sentence. Note that ‘the larviciding trial’ should be replaced with ‘a larviciding trial’ as the specific trial being investigated in this paper has not yet been introduced or described. Suggested wording: In the present study, we tested the hypothesis that the implementation of a larviciding trial in the city of Yaoundé will improve knowledge and practices relating to malaria and mosquitoes, as well as increase people’s positive perceptions towards larviciding.

11. Quick clarification. Line 149 – the authors describe the focus of the qualitative survey. It is unclear how 1) people’s knowledge and attitudes on preventive measures is different from 3) prevention measures. Do the authors mean the preventative practices reported as being undertaken by interviewees?

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Reviewer #2: No

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Knowledge, practices and perceptions of communities during a malaria larviciding randomized trial in the city of Yaoundé, Cameroon

PONE-D-21-27631R2

Dear Dr. Antonio-Nkondjio,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Guangyu Tong

Academic Editor

PLOS ONE

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