Mapping the landscape of data sources for diseases caused by harmful algal blooms in Southeast Asia: a systematic scoping review on the Philippines, Malaysia and Indonesia

Review
The article is very much relevant to the scope of UCL Open Environment, focusing on an often understudied nexus in an region that is directly feeling the health impacts of the specific environmental driver. The introduction very concretely outlines the purpose of the article, and why it is relevant to other scholarship. In recognizing that assessing the burden of disease at this ocean-human health nexus is difficult and often a gap, it is clear how this article attempts to set up opportunities to fill that space. The methodology shows how this research is needed for the region, and how it might be scaled up in others. The results show that this is a necessary study area that illuminates an area burdened by harmful algal bloom toxin exposures. HAB-related diseases sit within the above scope of UCL Open Environment, and very diligently fulfills the journal's requirements.

As mentioned both above and in the article, HAB-related diseases remain an understudied field that is not well understood by many populations, sometimes including those directly exposed to toxins. Therefore, this article is certainly an original contribution to the field, and the methodology for data extraction and subsequent results identifies that this gap is new and requires further research. Health data can often remain fragmented across various sources and subject areas, especially when the health concern is interdisciplinary in scope. The research area of ocean and human health has been diligently crafted to bridge some of these fragmented areas, and the article identifies just how necessary this type of work continues to be. The flowchart in Figure 5 of the article in particular works powerfully to illuminate the "ecosystems of health data," affirming these gaps that have to be filled and disjointed spaces that have to be further connected. The section on comparisons with existing monitoring systems and the importance of multi-sectoral collaborations is significantly prudent, and strongly supports the idea of integrating public health systems with HAB monitoring frameworks, with the study discussed providing an essential example of where this integration would prove beneficial.

The article engages with recent scholarship, including articles published within the last year. Many of the citations in the bibliography come from the last five to ten years, reflecting the effort of the authors to collect relevant information and literature when conducting the research to build the article. Appendix C includes articles as recent as 2019, and maintains a strong balance of sources to accurately collate the data needed for the work conducted. The body of the article works well to weave the sources in a way that shows the relevance of the issue and how the recent research, while discussing many of the issues the article details, must continue to work towards integration in order to advance progress.

The argument is strong, well-researched, and coherent. The article would benefit from one more read-through regarding some small grammatical and spelling errors, but not in regards to anything major that would significantly distract the reader or dampen the impact of the research. The article is particularly adept in using recent and current gaps in monitoring and analysis through a conducted study to ensure the need for integration. The figures and tables are helpful in navigating the body of the article, and are placed well throughout the text to ensure easy navigation for the reader.

The overall style and presentation of the article are appealing to the reader and invite engagement. The introduction could be improved slightly by expanding a bit more on what HABs are, perhaps even with an image, and about the development of the ocean and human health field as it relates to this article. The footnotes could also be edited slightly to be more appealing to the reader as one goes through the document.

The length of the article is comprehensive without being overwhelming. No change regarding length is recommended.

Thank you for the chance to read this compelling document, and I look forward to seeing this paper's hopeful publication.

Note:
This review refers to round 1 of peer review.

Review
This review aims to identify the data sources and flows for reporting of poisonings from harmful algal blooms (HABs) in Southeast Asia. Gaps in understanding of the burden of disease from these poisonings is worthy of investigation and there are few initiatives to do so, making this review interesting for readers. The paper would be strengthened by improved discussion of the clinical presentations, diagnosis, and case definitions of these conditions, and broader considerations of the public health surveillance frameworks in these countries.
Below are some minor and major comments for the authors to consider.

Major:
An important objective of this paper is to identify sources of data on the surveillance for and burden of poisoning from algal blooms. The authors used a review of the published literature to identify these surveillance data and flows. Often, public health surveillance data are not presented in scientific domains although this review seems to include also some pieces from the grey literature. The paper would benefit from a better description of what should be captured in the review undertaken and what is likely being missed. Might it be useful to look at public health surveillance data publicly available from these countries? Perhaps this was done but not mentioned in the paper.
A major limitation of the paper is the absence of any discussion of what defines a clinical case of poisoning and how these should be diagnosed. The literature about the spectrum of symptom presentations, gold standards for diagnosis, any available evidence about the sensitivity or specificity of various case definitions, and any studies about health care seeking behaviors for these or similar illnesses would be useful for the reader to contextualize the information presented. If the authors want to advocate for improved surveillance and diagnosis of these conditions, it would be prudent to set out what they believe improved systems would be, including how patients might be screened and cases identified. Should systems focus only on outbreaks or do the authors believe that individual cases should be identified?

The discussion section includes commentary on surveillance and reporting mechanisms generally. These countries likely have existing surveillance and reporting processes for other disease and public health problems and any future efforts related to these poisonings should use the same infrastructure that already exists. The more pressing issue seems to be how to diagnose cases and there is no discussion or information presented in the paper about how this occurs or how it could be improved.

Why were the tetrodotoxin outbreaks included in the results? It’s understandable that they may have been reviewed to understand if they included data useful for the review, but why were they included in the results? This often presents as paralysis, so seems unlike the other clinical presentations.

If the purpose of surveillance data is for public health action, it would be useful for the authors to outline what the action would be following surveillance for human cases of poisoning. In addition, what might be the value of surveillance and action based on algal blooms instead? What kind of action should be taken to reduce risk and how quickly does this need to happen to make a difference?

Minor comments:
Abstract: in the results, “secondary data reviews” seem more like a kind of method rather than a data source. The results say that “xx studies” were included, but many of the data sources in the review were newspaper articles and others that do not seem to indicate they are research studies.

Results:
Figure 2: Consider revising so that the type of articles are stacked bar charts with colors representing each country. The number of papers per country can be easily presented as text alone.
Figure 4 seems unnecessary.
Line 209 – Consider also summarizing the data available from Indonesia as you’ve done for the other countries.
Do the reported outbreaks align with known algal blooms? Was that part of the definition of a ‘case’?
The papers are presented sequentially, but there is little presentation of how they overlap.

Discussion:
Lines 331 – if the data come from physician observations of outbreaks, there might not be any specific funding for the activity. It would make sense to name a donor of a specific surveillance system, but in the absence of that, what kinds of financing were the authors looking for?
Lines 335-339 – These questions seem more relevant for surveillance systems than for one-off outbreak reporting.
Line 350 – Alerts are often used to bring attention to a recent threat or outbreak, rather than an individual case of a particular disease. Are the authors suggesting alerts based on the observation of blooms or of outbreaks of disease?
Line 386 – prevention campaigns are not typically surveillance systems.
Lines 404 – 405 – This is a good example of case finding efforts, but nothing described in the paper suggests that they were mitigating risk or reducing exposure.

Note:
This review refers to round 1 of peer review.

Review
This is a well-written and robust review that addresses a significant public health problem, closely aligned to the remit of the Journal.
General Comments
The references do not match the numbers in the text, for example Pastor is 52 in the text and 50 in the reference list, the total references in the text is 74 compared to 72 in the list.
If possible, even some limited detail about the health systems (in particular public health) of the countries would be of benefit in the introduction - do any of the countries have mandatory reporting of e.g. food poisoning (like the UK Health Protection Notification Regulations?). This would help to frame the discussion.

Specific comments
1. Title - this paper is about surveillance, can the title be changed to Mapping......harmful algal bloom-related disease surveillance...and should "on" be "of"?
2. Abstract - again try and include the term surveillance
3. Abstract - lines 25 & 26 - please say a "complimentary Google Scholar search in the Bahasa Indonesia language"
4. Line 50 - the end of the date is missing (1970s?)
5. Table 1. Typo - "respoiratory" row 4
6. Line 95 - should eight be seven if palytoxicosis and ostreopsis are together?
7. 118 explain keracunan
8. 133 explain snowball sampling (backward citation searching?)
9. Figure 1. there is an arrow (bottom right box) incorrectly formatted
10. Figure 1. Included studies = 22 results say n=20, what is studies included versus report of included?
11. Figure 2. add x-axis label (count)
12. 166 - change kept in pool to "included in final synthesis"
13. 174 say "toxin-type"
14. Table 4. Formatting can be difficult to read (column 4)
15. Table 4. Word Pareno formatting
16. 194 space needed after methods
17. 254 two cases of paralytic shellfish...
18. 286 - does the journal require P. bahamense to be italicised?
19. 317 monitoring change to surveillance
20. Figure 5 is a result - and should be in the results section
21. 352 sentence needs rewritten. Alternatively...
22. 461 Exacerbate, not sure this is known, perhaps better "affect"

Note:
This review refers to round 1 of peer review.