Prevalence of malaria and helminth infections in rural communities in northern Sierra Leone, a baseline study to inform Ebola vaccine study protocols

Frank Baiden; Suzanne Fleck; Bailah Leigh; Philip Ayieko; Daniel Tindanbil; Tuda Otieno; Bolarinde Lawal; Mattu Tehtor; Maariam Rogers; Lazarus Odeny; Mary H. Hodges; Mustapha Sonnie; Mohamed Samai; David Ishola; Brett Lowe; Deborah Watson-Jones; Brian Greenwood

doi:10.1371/journal.pone.0270968

Peer Review History

Original SubmissionDecember 7, 2021
28 Feb 2022 Decision Letter - Adrian J.F. Luty, Editor PONE-D-21-38636Prevalence of malaria and helminth infections in rural communities in northern Sierra Leone, a baseline study to inform Ebola vaccine study protocolsPLOS ONE Dear Dr. Baiden, 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.After careful review, there are a certain number of modifications required, as listed below. Please submit your revised manuscript by Apr 14 2022 11:59PM. 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. 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If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. Additional Editor Comments (if provided): Modification of the manuscript according to the following comments will help improve its overall quality: 1. MDA regimens: lines 117 - 121 indicate that, since 2018, school-aged children (SAC) were the sole recipients of (annual) ivermectin plus albendazole, although this age-group had been receiving albendazole every 6 months up until 2016 when it was deemed no longer necessary. Can the authors clarify from when SAC received albendazole every 6 months, and indicate how that treatment was integrated with the combined ivermectin-albendazole MDA given to all aged >5 up until 2017. Also, in the Sierra Leonean context, for clarity they should specify what age-group constitutes SAC. 2. Sample procedures: lines 153 - 159 outline the quality control procedure used for microscopical diagnosis of plasmodial parasites. Was no such confirmatory procedure adopted for the Kato-Katz-based diagnoses? 3. The rate of agreement to participate by household heads was appreciably lower in the non-riverine community. If there were consistent reasons found for this, they should be detailed. 4. The authors should clarify whether the Ebola vaccines under study are intended to be tested in specific age groups. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions 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. 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The results are great to present in the manuscript, however the presentation of the results could be improved to bring clarity to the manuscript. The following are my specific comments: Abstract section In the results section of the abstract, the authors could include at least brief results of the lymphatic filariasis and onchocerciasis results. Results section - The headings in the results section should be improved to bring understanding to what is being presented. The first item presented is demography stuff so the authors could have a heading like “Demographic characteristics of the study population”. Currently there is no heading for this presentation. Again such headings as “Helminths” does not tell much. It could have been “Helminth infections in the population” etc - Under Malaria parasitaemia, the authors could present the co-infection parasites eg how many patients were co-infected with Plasmodium falciparum and P. vivax and all the other coinfections too. The scientific world will be interested to know which parasites infected the people as coinfection. - Also with the helminth infections, the authors do not state which parasites were the co-infections. Such information are important to publish. - It would have been great if the authors present the different parasites differently under different groups. For instance the presentation could have been done under the following:, Soil Transmitted helminths, Schistosomiasis, blood associated parasites (Onchocerciasis and Wuchereria bancrofti). This would have brought clarity to the results. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. 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Revision 1
4 Jun 2022 Author Response Reviewers’ comments and actions taken. We are grateful to the reviewers for their compliments and critical review of the manuscript. We have found their comments to be useful and we have accordingly revised the manuscript. Below is a point-by-point account of how we have used the comments to revise the manuscript. Comment 1 1. MDA regimens: lines 117 - 121 indicate that, since 2018, school-aged children (SAC) were the sole recipients of (annual) ivermectin plus albendazole, although this age-group had been receiving albendazole every 6 months up until 2016 when it was deemed no longer necessary. Can the authors clarify from when SAC received albendazole every 6 months, and indicate how that treatment was integrated with the combined ivermectin-albendazole MDA given to all aged >5 up until 2017. Also, in the Sierra Leonean context, for clarity they should specify what age-group constitutes SAC. Response 1 We have revised the manuscript in lines 122-128 with a clarification of this section as follows Deworming of School-Aged Children (SAC) with albendazole has been part of the public health system in Sierra Leone for many years. The program defined SAC to be children aged between 5 and 14 years. A national impact survey in 2016 however demonstrated that the intervention was no longer justified. MDA-LF with ivermectin and with albendazole was undertaken annually from 2008-2017 for everyone over 5 years of age. Since 2018 however, this activity has been targeted at only SAC. Deworming of pre-SAC with albendazole continues to be undertaken every six months. This is done through local health facilities and community outreach services. . Comment 2 2. Sample procedures: lines 153 - 159 outline the quality control procedure used for microscopical diagnosis of plasmodial parasites. Was no such confirmatory procedure adopted for the Kato-Katz-based diagnoses? Response 2 We have revised the manuscript in lines 177-179 to improve clarity as follows: As part of quality control for the procedure, the microscopic examination took place within 30 minutes after sample processing. Ten percent of negative samples and all positive samples were reread by a senior laboratory staff immediately after the first reading to validate the results. Comment 3 3. The rate of agreement to participate by household heads was appreciably lower in the non-riverine community. If there were consistent reasons found for this, they should be detailed. Response 3 We agree to the suggestion and have revised in lines 307-311 to include the following Response to participation in the survey was better in the riverine than non-riverine communities. The riverine communities are closer to the offices of the Ebola vaccine project. It is conceivable that community engagements activities in the Ebola vaccine project may have impacted positively on the willingness of people in the riverine communities to participate in the survey compared to people in the non-riverine communities. Comment 4 4. The authors should clarify whether the Ebola vaccines under study are intended to be tested in specific age groups. Response 4 We have revised the manuscript in lines 86-87 as follows The Ebola vaccines are evaluated in persons aged one year and older. Reviewer #1: Comment 5 The authors present their manuscript on the prevalence of malaria and helminth infections in rural communities in northern Sierra Leone. This is a baseline study to inform Ebola vaccine study protocols. The results are great to present in the manuscript; however, the presentation of the results could be improved to bring clarity to the manuscript. The following are my specific comments: Abstract section: In the results section of the abstract, the authors could include at least brief results of the lymphatic filariasis and onchocerciasis results. Response 5 We agree with the reviewer. Within the constraints of word limitation, we have included the following statement in the Results section (lines 58-59) of the abstract Onchocerca volvulus and Wuchereria bancrofti infections were found in 3.3% and 0.4% of participants respectively. Comments 6 Results section - The headings in the results section should be improved to bring understanding to what is being presented. The first item presented is demography stuff so the authors could have a heading like “Demographic characteristics of the study population”. Currently there is no heading for this presentation. Again such headings as “Helminths” does not tell much. It could have been “Helminth infections in the population” etc It would have been great if the authors present the different parasites differently under different groups. For instance, the presentation could have been done under the following: Soil Transmitted helminths, Schistosomiasis, blood associated parasites (Onchocerciasis and Wuchereria bancrofti). This would have brought clarity to the results. Response 6 We appreciate the point made by the reviewer. We are however further guided by the “Instructions to Authors” provided by PLOS to keep headings and sub-headings to a minimum. Taking the reviewer’s suggestions into account and recognizing the limitations imposed by the journal’s requirements, we have revised the manuscript to includes the following sub-headings: • Soil-transmitted helminths and schistosome infections (line 265) • Blood associated parasites (O. volvulus and W. bancrofti) (line 292) We believe this has improved the clarity of presentation of the results. Comment 7 Under Malaria parasitaemia, the authors could present the co-infection parasites eg how many patients were co-infected with Plasmodium falciparum and P. vivax and all the other coinfections too. The scientific world will be interested to know which parasites infected the people as coinfection. Response 7 The manuscript has been revised in lines 241-247 to include this information as follows. A single malaria parasite species was identified in 288 slides, two species were identified in 13 slides (11 involved mixed infections of P. falciparum and P. malariae while two involved mixed infections of P. falciparum and P. ovale) and speciation was not reported for 8 slides. Comment 8 Also with the helminth infections, the authors do not state which parasites were the co-infections. Such information are important to publish. Response 8 This information is provided in the manuscript (lines 267-271) as follows The positive helminth infections comprised 102 (12.5%) cases of hookworm, 11 (1.3%) cases of T. trichiura, 10 (1.2%) cases of S. mansoni and two (0.2%) cases of A. lumbricoides. The three stool samples showing mixed infections were two samples with hookworm and T. trichiura mixed infection, and one with hookworm and schistosomiasis mixed infection (Table 2). When submitting your revision, we need you to address these additional requirements. 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf 2. Please include a complete copy of PLOS’ questionnaire on inclusivity in global research in your revised manuscript. Our policy for research in this area aims to improve transparency in the reporting of research performed outside of researchers’ own country or community. The policy applies to researchers who have travelled to a different country to conduct research, research with Indigenous populations or their lands, and research on cultural artefacts. The questionnaire can also be requested at the journal’s discretion for any other submissions, even if these conditions are not met. Please find more information on the policy and a link to download a blank copy of the questionnaire here: https://journals.plos.org/plosone/s/best-practices-in-research-reporting. Please upload a completed version of your questionnaire as Supporting Information when you resubmit your manuscript. 3. We note that the grant information you provided in the ‘Funding Information’ and ‘Financial Disclosure’ sections do not match. When you resubmit, please ensure that you provide the correct grant numbers for the awards you received for your study in the ‘Funding Information’ section Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. Attachments Attachment Submitted filename: Response to reviewer comments-FINAL.docx https://doi.org/10.1371/journal.pone.0270968.r002
22 Jun 2022 Decision Letter - Adrian J.F. Luty, Editor Prevalence of malaria and helminth infections in rural communities in northern Sierra Leone, a baseline study to inform Ebola vaccine study protocols PONE-D-21-38636R1 Dear Dr. Baiden, 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. An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Adrian J.F. Luty, PhD Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0270968.r003
Formally Accepted
27 Jun 2022 Acceptance Letter - Adrian J.F. Luty, Editor PONE-D-21-38636R1 Prevalence of malaria and helminth infections in rural communities in northern Sierra Leone, a baseline study to inform Ebola vaccine study protocols Dear Dr. Baiden: I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org. If we can help with anything else, please email us at plosone@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Adrian J.F. Luty Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0270968.r004

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