Teratogenic Effects and Outcomes of Congenital Oropouche Virus Infection: Current Evidence, Pathophysiological Mechanisms, and Research Priorities

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General comments:

 

Pomar et al. bring the insightful review entitled “Teratogenic Effects and Outcomes of Congenital Oropouche Virus Infection: Current Evidence, Pathophysiological Mechanisms, and Research Priorities”. This review summarizes current knowledge regarding congenital OROV infection. The authors try com compared the pregnancy and fetal outcomes with other arbovirus infection, especially ZIKV however, the comparisons only occur in one section of the paper very briefly. The manuscript is well written but needs revision to improve the quality of the manuscript.

 

Please see comments listed below.

 

Major comments:

1. Please check the references carefully. Several references appear to be duplicated but are assigned different reference numbers (e.g., 3 and 26; 4 and 19; 5 and 20; 12 and 22; 13 and 23; 14 and 24; 15 and 21; 16 and 25). Furthermore, in the text the references should be organized in numeric order, and the first reference starts as [1,4,5], while should be [1-3].
2. The authors should avoid long sentences in the text to avoid misunderstanding of the text. I would consider editing the second paragraph of the introduction (Lines 50-54)
3. Please add a reference for the information present in lines 84-89 and 92-95.
4. In the Figure 1 the authors modify the bar plot from PAHO only to add references from 4 papers that describe adverse pregnancy outcomes, and they add the figure after discussing only Brazil surveillance. However, when you go back to the original figure, PAHO use as references the ministry of health of Brazil, Cuba, Colombia, Panama, Peru, Guyana, Venezuela and none of the papers added to the figure. I highly suggest to the authors to make their own figure related to OROV epidemiology during the 2023-205 outbreak. This figure could be a geographic distribution map indicating the distribution of the cases over the years (Panel A of figure 1). It would also be interesting if the authors could dissect the cases by sex and stratify by age (Panel B figure 1). Finally, highlight the occurrence of adverse outcomes in a geographic map (Panel C, figure 1).
5. A review paper with a proper flow should have a smooth transition between sections. In this review paper, could be improved in the connection between sections and the reading flow.
6. The “3.3. Pathophysiology” is focused in experimental models rather than actual pathophysiology of the infection in humans. It’s recommended to chance the topic name to address properly what is in the topic.
7. The authors try com compared the pregnancy and fetal outcomes with other arbovirus infection, especially ZIKV however, the comparisons only occur in one section of the paper very briefly. It would be interesting to expand the section and include more details from other congenital virus infection outcomes.
8. The authors compare OROV congenital infection to WNV infection. Could the authors clarify the rate of occurrence of congenital WNV infection? As far is known women infected with WNV during the pregnancy presents a very low risk of vertical transmission. The infection itself is more dangerous to the maternal side than the fetus side.
9. A final figure with the overall information present in this manuscript would improve the review paper. A complete scenario of OROV infection during the pregnancy and the fetal outcomes could potentially help to understand the gaps and resume what is already known.

Author Response

We thank the reviewer for the thorough evaluation of our manuscript and for the constructive comments. We have carefully revised the manuscript accordingly. Our responses are provided below.

 

1) Please check the references carefully. Several references appear to be duplicated but are assigned different reference numbers (e.g., 3 and 26; 4 and 19; 5 and 20; 12 and 22; 13 and 23; 14 and 24; 15 and 21; 16 and 25). Furthermore, in the text the references should be organized in numeric order, and the first reference starts as [1,4,5], while should be [1-3].

We thank the reviewer for identifying these inconsistencies. The reference list has been thoroughly reviewed, duplicate references were removed, and all reference numbering was updated throughout the manuscript.

 

2) The authors should avoid long sentences in the text to avoid misunderstanding of the text. I would consider editing the second paragraph of the introduction (Lines 50-54).

Response: We agree with the reviewer. This paragraph was revised to read: “Historically, OROV infection was considered a self-limiting febrile illness characterized by fever, headache, myalgia, arthralgia, and occasional neurological manifestations. However, large outbreaks reported since 2023 in South America and the Caribbean have renewed interest in the virus. This attention has been further heightened by emerging evidence suggesting adverse pregnancy outcomes after maternal infection.”

 

3) Please add a reference for the information present in lines 84-89 and 92-95.

Response: We thank the reviewer for pointing this out. Additional references have been added to support these statements:

• Sciancalepore, S.; Schneider, M.C.; Kim, J.; Galan, D.I.; Rivière-Cinnamond, A. Presence and Multi-Species Spatial Distribution of Oropouche Virus in Brazil within the One Health Framework. Med. Infect. Dis. 2022, 7, 111.
• Zhang, Y.; Liu, X.; Wu, Z.; et al. Oropouche Virus: A Neglected Global Arboviral Threat. Virus Res. 2024, 341, 199318. https://doi.org/10.1016/j.virusres.2024.199318.

 

4) In the Figure 1 the authors modify the bar plot from PAHO only to add references from 4 papers that describe adverse pregnancy outcomes, and they add the figure after discussing only Brazil surveillance. However, when you go back to the original figure, PAHO use as references the ministry of health of Brazil, Cuba, Colombia, Panama, Peru, Guyana, Venezuela and none of the papers added to the figure. I highly suggest to the authors to make their own figure related to OROV epidemiology during the 2023-205 outbreak. This figure could be a geographic distribution map indicating the distribution of the cases over the years (Panel A of figure 1). It would also be interesting if the authors could dissect the cases by sex and stratify by age (Panel B figure 1). Finally, highlight the occurrence of adverse outcomes in a geographic map (Panel C, figure 1).

Response: We thank the reviewer for this suggestion. We agreed that the original figure did not optimally illustrate the epidemiological context of OROV infection during pregnancy, and therefore completely redesigned Figure 1.

The revised figure now presents the geographical distribution of confirmed autochthonous OROV cases reported during the 2024 outbreak in South America and the Caribbean, together with the locations and recruitment periods of the main published pregnancy cohorts and case series reporting adverse pregnancy outcomes, vertical transmission, or congenital infection.

Although we considered the reviewer’s suggestion to stratify cases according to age and sex, these data were not consistently available across all affected countries in the PAHO reports and national surveillance sources. We therefore chose to focus the figure on the epidemiological distribution of OROV transmission and on the geographic and temporal relationship between the outbreak and the reported pregnancy-associated cases, which we believe is more directly relevant to the objective of this review. We also changed the reference to the figure in the text to read: “During the 2023-2025 resurgence, surveillance systems in Brazil identified the first fatal cases and clusters of adverse pregnancy outcomes. Reported pregnancy outcomes included spontaneous abortions, stillbirths, and congenital anomalies following maternal infections that occurred during the 2024 outbreak (Figure 1)”

 

5) A review paper with a proper flow should have a smooth transition between sections. In this review paper, could be improved in the connection between sections and the reading flow.

Response: we agree with the reviewer and revised the manuscript to improve transitions between sections and strengthen the overall narrative flow.

Changes in the manuscript:

• Epidemiology of OROV infection and pregnancy exposure: “The increasing recognition of adverse pregnancy outcomes during the 2024 outbreak has renewed interest in understanding the biological mechanisms underlying maternal-fetal transmission and fetal injury. Experimental studies have therefore become essential for investigating the patho-genesis of congenital OROV infection.”
• Experimental models and mechanisms of OROV vertical transmission and fetal injury: “These experimental findings provide biological plausibility for the occurrence of congenital infection and fetal injury. However, understanding the clinical presentation of OROV infection in pregnant women and its diagnosis remains essential to identify exposed pregnancies and contextualize their outcomes.
• Congenital OROV infections and fetal / neonatal outcomes: “The broad clinical spectrum and overlap with other congenital infections create important diagnostic challenges and highlight the need for a structured approach to confirming congenital OROV infection.”
• Discussion: “The findings summarized in this review provide converging epidemiological, clinical, pathological, and experimental evidence supporting the emergence of OROV as a potential congenital pathogen. The following discussion evaluates the strength of this evidence using established teratogenicity frameworks.”

 

6)The “3.3. Pathophysiology” is focused in experimental models rather than actual pathophysiology of the infection in humans. It’s recommended to change the topic name to address properly what is in the topic.

Response: we agree with the reviewer. Since the section mainly summarizes findings from experimental studies, we revised the title to better reflect its contents.

Changes in the manuscript: renamed section 3.3 as: “Experimental Models and Mechanisms of OROV Vertical Transmission and Fetal Injury”.

 

7)The authors try to compare the pregnancy and fetal outcomes with other arbovirus infections, especially ZIKV however, the comparisons only occur in one section of the paper very briefly. It would be interesting to expand the section and include more details from other congenital virus infection outcomes.

Response: we thank the reviewer for this suggestion. Although comparisons with other arboviral infections were already incorporated throughout several sections of the manuscript, including maternal clinical presentation, diagnostic considerations, vertical transmission, congenital manifestations, and the discussion of teratogenicity, we agree that a more structured synthesis would improve readability and facilitate comparison between congenital OROV infection and other neurotropic arboviral infections. To emphasize this comment, a comparative summary table was added highlighting key similarities and differences between congenital OROV, Zika virus, West Nile virus, and Tonate virus infections:

Table 1. Comparison of congenital manifestations and available evidence across selected neurotropic arboviral infections.

Characteristics reported	OROV	ZIKV	WNV	VEE
Evidence of vertical transmission	Yes	Yes	Yes	Yes
Estimated rate of vertical transmission	No	26%	4%	No
Placental infection	Yes	Yes	Yes	Yes
Pregnancy loss (miscarriage, stillbirth)	Yes	Yes	Yes	Yes
Microcephaly	Yes	Yes	Yes	Yes
Ventriculomegaly	Yes	Yes	Yes	Yes
Cerebral atrophy/destructive lesions	Yes	Yes	Yes	Yes
Corpus callosum abnormalities	Yes	Yes	Yes	Yes
Arthrogryposis	Yes	Yes	No	Yes
Ocular abnormalities	Yes	Yes	Yes	Yes

 

8)The authors compare OROV congenital infection to WNV infection. Could the authors clarify the rate of occurrence of congenital WNV infection?

Response: we clarify in the added table (see above) that congenital West Nile virus infection appears to be rare (4% in a single study) despite numerous reported maternal infections.

 

9) A final figure with the overall information present in this manuscript would improve the review paper.

Response: we thank the reviewer for this suggestion. We agree that graphical summaries can improve readability in review articles. However, following the extensive revisions performed in response to the reviewers' comments, the manuscript now includes a completely redesigned epidemiological figure (Figure 1) and an expanded comparative figure and summary table highlighting the main features of congenital OROV infection and related arboviral syndromes. We therefore felt that an additional summary figure would largely duplicate information already presented elsewhere in the manuscript and unnecessarily increase its complexity. For this reason, we elected not to add a further figure.

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors Overall Assessment The manuscript addresses congenital Oropouche virus infection, a timely topic of clear clinical relevance. Given the nature of this submission, this evaluation is provided as an overall assessment rather than a point-by-point critique. While the subject matter is interesting, the paper lacks novelty, presents a modest case series, and requires substantial revision to improve its focus and conciseness. Key Strengths * Highly relevant and timely topic within emerging arboviral infections. * Well-written text with an appropriate academic tone. Major Criticisms * Originality & Sample Size: The manuscript does not introduce innovative insights, and the presented case series is quite modest. * Structure & Redundancy: The text is overly verbose, with several concepts—particularly clinical symptomatology—repeated multiple times without deeper analysis or a clear breakdown of the most frequent clinical manifestations across the cited studies. * Incomplete Comparative Analysis: Comparisons with other arboviruses are mentioned repeatedly, but their similarities and differences are not adequately explored or analyzed. * Figures & References: Figure 2 appears largely illustrative/decorative rather than informative. Furthermore, the reference list is insufficient and needs to be expanded with relevant literature. Recommendation & Actionable Revision Steps The manuscript requires substantial editing to streamline the text and highlight its core findings. Specifically, the authors should: 1. Synthesize and trim the narrative to eliminate repetitions and improve readability. 2. Focus on core clinical data, explicitly detailing the frequency of key symptoms reported in the literature. 3. Thoroughly analyze comparisons with other arboviruses by highlighting key similarities and differences. 4. Remove Figure 2 and expand the reference list to provide adequate scholarly context.

 

Author Response

Reviewer 2:

Overall Assessment The manuscript addresses congenital Oropouche virus infection, a timely topic of clear clinical relevance. Given the nature of this submission, this evaluation is provided as an overall assessment rather than a point-by-point critique. While the subject matter is interesting, the paper lacks novelty, presents a modest case series, and requires substantial revision to improve its focus and conciseness.

Key Strengths * Highly relevant and timely topic within emerging arboviral infections. * Well-written text with an appropriate academic tone.

Major Criticisms * Originality & Sample Size: The manuscript does not introduce innovative insights, and the presented case series is quite modest.

* Structure & Redundancy: The text is overly verbose, with several concepts—particularly clinical symptomatology—repeated multiple times without deeper analysis or a clear breakdown of the most frequent clinical manifestations across the cited studies.

* Incomplete Comparative Analysis: Comparisons with other arboviruses are mentioned repeatedly, but their similarities and differences are not adequately explored or analyzed.

* Figures & References: Figure 2 appears largely illustrative/decorative rather than informative. Furthermore, the reference list is insufficient and needs to be expanded with relevant literature.

Response: we thank the reviewer for this comment. We acknowledge that the currently available clinical evidence remains limited and is largely based on case reports, case series, surveillance investigations, and a small number of cohort studies. The objective of this invited review was not to present novel clinical data, but rather to provide a comprehensive and timely synthesis of the rapidly evolving literature on congenital OROV infection and to integrate epidemiological, clinical, pathological, and experimental evidence into a single framework. In response to the reviewers’ comments, we have further strengthened the manuscript by expanding the comparative analysis with other congenital arboviral infections, adding a new comparative summary table, redesigning Figure 1, and improving the overall structure and readability of the review.

 

Recommendation & Actionable Revision Steps The manuscript requires substantial editing to streamline the text and highlight its core findings. Specifically, the authors should:

1. Synthesize and trim the narrative to eliminate repetitions and improve readability.

Response: to improve readability, repetitive discussions of placental infection, neurotropism, biological plausibility, and current knowledge gaps were streamlined across several sections. Some comparative descriptions previously repeated in the text were condensed and summarized in a new comparative table (see response to reviewer 1).

 

2. Focus on core clinical data, explicitly detailing the frequency of key symptoms reported in the literature.

Response: we thank the reviewer for this comment and agree that some concepts were repeated throughout the manuscript. We revised the text to improve conciseness, reduce redundancy, and strengthen the synthesis of available evidence. To improve the clinical relevance of the review, we also revised the section describing maternal OROV infection and incorporated pooled prevalence estimates from a recent systematic review and meta-analysis (Wang et al., 2026). The frequencies and 95% confidence intervals of the principal manifestations are now reported in the text. The manuscript was revised to read: “The clinical spectrum of OROV infection ranges from asymptomatic infection to acute febrile disease and, more rarely, severe neurological or systemic complications. Following an incubation period of approximately one week (1-10 days), symptomatic individuals typically present with a sudden onset of fever (pooled prevalence 94%, 95% CI 90-98%), accompanied by headache (87%, 95% CI 84-91%), myalgia (73%, 95% CI 67-80%), arthralgia (51%, 95% CI 41-62%), chills (49%, 95% CI 26-72%), and fatigue or weakness (49%, 95% CI 21-77%). Retro-orbital pain is also commonly reported (43%, 95% CI 35-52%). Because these manifestations overlap considerably with those of den-gue, chikungunya, Zika, and other arboviral diseases, clinical diagnosis alone remains unreliable in areas where multiple arboviruses co-circulate[14,18,39]. Gastrointestinal manifestations are frequent and include loss of appetite (41%, 95% CI 28-55%), nausea or vomiting (36%, 95% CI 31-42%), abdominal pain (18%, 95% CI 9-27%), and diarrhea (20%, 95% CI 13-26%). Other reported symptoms include dizziness (35%, 95% CI 21-49%) and photophobia (33%, 95% CI 12-54%). Cutaneous manifestations, such as rash (16%, 95% CI 9-23%) and pruritus (17%, 95% CI 8-26%), are less common and lack diagnostic specificity. Likewise, respiratory symptoms, including sore throat (29%, 95% CI 21-38%), may occur but are not considered defining features of the disease. Acute illness is usually self-limited, with symptom resolution occurring within several days. However, recurrent symptoms have been described in a substantial proportion of patients, re-sulting in a biphasic clinical pattern characterized by renewed fever, headache, and arthralgia 7-14 days after apparent recovery. While most infections remain uncomplicated, severe manifestations have occasionally been reported. Neurological compli-cations, including meningitis, encephalitis, and meningoencephalitis, are rare, with pooled prevalences below 1%, whereas hemorrhagic manifestations occur in approximately 4% of reported cases (95% CI 0-7%). During recent outbreaks, rare cases of hepatic dysfunction, renal impairment, and fatal disease have also been described. The clinical course of symptomatic OROV infections and pooled frequency ranges of symptoms and complications are summarized in Figure 2.”

 

3. Thoroughly analyze comparisons with other arboviruses by highlighting key similarities and differences.

Response: we substantially expanded the comparison with other congenital arboviral infections. Although such comparisons were already present throughout the manuscript, including in sections addressing maternal symptoms, diagnostic considerations, vertical transmission, fetal manifestations, and teratogenicity, we agreed that a more structured synthesis would improve readability. We therefore added a new comparative table summarizing key similarities and differences between congenital OROV, Zika virus, West Nile virus, Tonate virus, and Venezuelan equine encephalitis virus infections:

Table 1. Comparison of congenital manifestations and available evidence across selected neurotropic arboviral infections.

Characteristics reported	OROV	ZIKV	WNV	VEE
Evidence of vertical transmission	Yes	Yes	Yes	Yes
Estimated rate of vertical transmission	No	26%	4%	No
Placental infection	Yes	Yes	Yes	Yes
Pregnancy loss (miscarriage, stillbirth)	Yes	Yes	Yes	Yes
Microcephaly	Yes	Yes	Yes	Yes
Ventriculomegaly	Yes	Yes	Yes	Yes
Cerebral atrophy/destructive lesions	Yes	Yes	Yes	Yes
Corpus callosum abnormalities	Yes	Yes	Yes	Yes
Arthrogryposis	Yes	Yes	No	Yes
Ocular abnormalities	Yes	Yes	Yes	Yes

The table summarizes current evidence regarding vertical transmission, placental infection and fetal manifestations for Oropouche virus (OROV), Zika virus (ZIKV), West Nile virus (WNV), and Venezuelan equine encephalitis (VEE) virus infections. Findings are based on published human data and are intended to highlight similarities and differences among congenital arboviral syndromes.

 

4. Remove Figure 2 and expand the reference list to provide adequate scholarly context.

Response: we thank the reviewer for this comment. We agreed that the previous version of Figure 2 could be improved to increase its scientific value. Rather than removing the figure, we substantially revised it to provide a more informative summary of the clinical course of OROV infection. The revised figure now incorporates the pooled frequency ranges of the main clinical manifestations and their pooled frequency range reported in recent systematic review and meta-analysis, together with the temporal evolution of symptoms, the frequency of recurrent illness, persistent symptoms, and uncommon complications. We believe that the revised figure now provides a concise visual synthesis of the available clinical evidence rather than a purely illustrative representation.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The authors conducted an excellent narrative review regarding congenital OROV infection—covering clinical and epidemiological findings, pathophysiological mechanisms, and comparisons with congenital infections caused by other arboviruses, as well as experimental studies validating the findings observed in humans.
They also highlighted key points that still need to be clarified to establish OROV as a human teratogen—such as the critical period, the characterization of a congenital OROV syndrome, and relative risk—ideally through a cohort study.
This work represents a contribution of both clinical and methodological importance for future studies.

Author Response

Reviewer 3:

The authors conducted an excellent narrative review regarding congenital OROV infection—covering clinical and epidemiological findings, pathophysiological mechanisms, and comparisons with congenital infections caused by other arboviruses, as well as experimental studies validating the findings observed in humans.

They also highlighted key points that still need to be clarified to establish OROV as a human teratogen—such as the critical period, the characterization of a congenital OROV syndrome, and relative risk—ideally through a cohort study.

This work represents a contribution of both clinical and methodological importance for future studies.

 

Response: We thank the reviewer for this careful assessment of our manuscript and for the positive comments. We are pleased that the reviewer recognized the clinical and methodological relevance of this review, as well as the importance of integrating epidemiological, clinical, pathological, and experimental evidence regarding congenital OROV infection.

We also appreciate the reviewer's recognition of the key knowledge gaps highlighted in the manuscript, including the need to better define the critical period of susceptibility, quantify the risk of adverse outcomes, characterize a potential congenital OROV syndrome, and establish robust prospective pregnancy cohorts.

The reviewer did not raise any specific concerns requiring modifications to the manuscript.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have submited a revised version of their manuscript "Teratogenic Effects and Outcomes of Congenital Oropouche Virus Infection: Current Evidence, Pathophysiological Mechanisms, and Research Priorities". The authors have made a comprehensive effort to address the reviewers’ comments and have been highly responsive to the prior critiques. The revisions are satisfactory, and all concerns raised during the review process have been adequately addressed.

Reviewer 2 Report

Comments and Suggestions for Authors

The changes you did in the manuscritp and described in your reply are adequate, and no further observations are needed.