Epidemiological and Clinical Features of Mpox during the Clade Ib Outbreak in South-Kivu, Democratic Republic of the Congo: a Prospective Cohort Study
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Abstract
Background
Clade Ib, a new strain of the Clade I monkeypox virus, emerged in Eastern Democratic Republic of the Congo, sparking an international outbreak. Comprehensive studies are needed to assess its transmission dynamics and clinical presentation.
Methods
We conducted a prospective observational cohort study at Kamituga General Hospital in South Kivu, DRC, between May 2 and October 9, 2024. Sociodemographic, exposure and clinical data were collected from mpox suspected cases. Cases confirmed by Xpert® Mpox PCR were presumed Clade Ib infections (awaiting Clade confirmation) and followed through hospitalization and on days 29 and 59 post-diagnosis to assess clinical progression and outcomes.
Findings
Of 511 included suspected cases, 431 (84%) tested PCR positive; with 205 being women (47%). Age distribution was bimodal, with 279 (65%) individuals aged 15-34 years, and 63 (15%) children under five. Most cases (59%) reported contact with a suspected or confirmed mpox case; among adults, this was primarily a spouse, colleague or sexual partner, while for children, the primary contacts were parents or siblings. Comorbidities were rare (4%), including six (1%) HIV infections. Prodromal symptoms were present in 346 (88%) patients, active skin lesions in 414 (96%), mucosal lesions in 338 (82%), and lymphadenopathy in 295 (71%). In adults, lesions were more concentrated in the genital area, with 90% of adults presenting lesions in this region. In contrast, only 39% of children had genital lesions, with lesions more frequently found elsewhere on the body. Among 427 hospitalized patients, two deaths (0·5%) occurred. Among 315 patients with detailed hospital follow-up, complications were primarily genito-urinary (55%) or cutaneous (40%). Four of six pregnant women with recorded outcome (67%) had adverse pregnancy outcomes. Significant sequelae at days 29 and 59 were rare.
Interpretation
Clade Ib MPXV infections presented differently from previously reported Clade Ia and Clade IIb infections. In adults, the disease primarily affected the genito-urinary system, compatible with sexual transmission, while children mostly manifested extragenital lesions.
Funding
European & Developing Countries Clinical Trials Partnership (EDCTP2 and EDCTP3); Belgian Directorate-General Development Cooperation and Humanitarian Aid; Research Foundation – Flanders
Article activity feed
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Sergio Iván Valdés Ferrer
Review 1: "Epidemiological and Clinical Features of Mpox during the Clade Ib outbreak in South-Kivu, Democratic Republic of the Congo: A Prospective Cohort Study"
The review underscores critical findings, such as the high rate of adverse outcomes in pregnancy and the concerning mortality among children under five, while calling for further research to explore less severe cases and vaccination impacts.
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Sergio Iván Valdés Ferrer
Review of "Epidemiological and Clinical Features of Mpox during the Clade Ib outbreak in South-Kivu, Democratic Republic of the Congo: A Prospective Cohort Study"
Reviewers: S I V Ferrer (Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán) | 📗📗📗📗◻️
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This Zenodo record is a permanently preserved version of a Structured PREreview. You can view the complete PREreview at https://prereview.org/reviews/14232687.
Does the introduction explain the objective of the research presented in the preprint? Yes This preprint provides an overview of the clinical features and outcomes of Mpox infection, particularly Clade Ib in South Kivu DRC, being the main research questions: How is the clinical presentation and what are disease outcomes of the Clade Ib Mpox infection in South Kivu, DRC?Are the methods well-suited for this research? Highly appropriate They follow best practices throughout the …This Zenodo record is a permanently preserved version of a Structured PREreview. You can view the complete PREreview at https://prereview.org/reviews/14232687.
Does the introduction explain the objective of the research presented in the preprint? Yes This preprint provides an overview of the clinical features and outcomes of Mpox infection, particularly Clade Ib in South Kivu DRC, being the main research questions: How is the clinical presentation and what are disease outcomes of the Clade Ib Mpox infection in South Kivu, DRC?Are the methods well-suited for this research? Highly appropriate They follow best practices throughout the research. They are rigorously executed and provide a robust foundation for drawing valid conclusions. To enhance clarity, we recommend clarifying the definition of skin-to-skin contact, please explain if the contact was on apparently healthy skin or if it refers to contact with skin lesions, we recommend specifying the time of the contact as this may be important to give an idea of risk exposure. In "outcome and complications during hospitalization", we recommend to specify the cause of the in-hospital mortality of the two children; it is particularly important to clarify if the deaths were attributable to Mpox infection or due to other causes, this is important to interpret the implications for the pediatric population.Are the conclusions supported by the data? Somewhat supported The conclusions are mostly, but not always, thorough. They provide a reasonable interpretation of the data without overreaching or adding interpretations not reflected in the results. We recommend explaining the implications of the assumption that the mpox infections were caused by Clade Ib, given the statement "Clade-specific confirmation is currently unavailable". It could be important to support the aforementioned assumption with recent genomic analysis studies conducted in the geographical region of concern. Please consider explaining how the loss of participants was addressed during the follow-up. If this was not considered we recommend providing an explanation of the implications of the missing data during the follow-up in the conclusions.Are the data presentations, including visualizations, well-suited to represent the data? Highly appropriate and clear They thoroughly follow accessibility best practices and effectively communicate the results and key patterns in the data, making it very easy to comprehend or interpret the data. Figure 1 summarizes the demographics of the clinical presentation of Mpox, visually illustrating the distribution of lesions by body area and age group, making the images easier to interpret. Additionally, Kaplan-Meier curves are used to estimate the time from symptom onset to resolution. These graphs help us understand the progression and clinical behavior of Mpox clade Ib symptoms. Additionally, Figure 2 shows some images of the lesions of the patients in the study. The tables clearly present the data in a precise and summarized manner, with the symbolism and meaning of abbreviations explained in the table descriptions. For example, Table 1 provides the demographics of the study population, along with the p-values.How clearly do the authors discuss, explain, and interpret their findings and potential next steps for the research? Very clearly They demonstrate clarity, depth, and insight in their discussion, explanation, and interpretation of their findings and potential next steps. The authors clearly discuss and interpret their findings, offering a comprehensive analysis of the Clade Ib outbreak in South Kivu by comparing it to other Mpox outbreaks, particularly Clade Ia and Clade IIb. For example, they point out that while zoonotic spillover is typically a driver in Clade Ia outbreaks, it was rare in their cohort, with sexual contact being a significant driver of transmission in the Clade Ib outbreak. This finding aligns with patterns observed in Clade IIb outbreaks, though they note an important difference: in their study, the transmission occurred predominantly through heterosexual contact, as opposed to male-to-male sexual contact, which was more common in the global Clade IIb outbreak. The authors also clearly interpret the implications of their findings in the context of the population they studied, emphasizing the role of occupation (such as sex workers and mine workers) and sexual behaviors in shaping transmission dynamics. In terms of next steps for research, the authors suggest several areas for future investigation. They highlight the need for further studies to better understand transmission dynamics, particularly in children and in resource-limited settings. They also call for more research into the long-term outcomes of Mpox infections, such as the impact of the disease on pregnancy and fetal development, and the potential for vertical transmission Their interpretation of the data is logically structured and informed by both the limitations of their study and comparisons with other outbreaks.Is the preprint likely to advance academic knowledge? Somewhat likely This preprint studies a recent Mpox outbreak and how it differs from previous strains. The findings from this study are significant, as they report how the Clade Ib strain of Mpox affects various demographics within Congo including individuals aged 1 week to 79 years, mine workers and sex workers. It also goes into great detail about the symptoms of this strain and further discusses how symptoms varied from each identified demographic. However, it is important to note that these results may not be generalizable, as the study was conducted in a "remote area of Eastern DRC, where access to high-quality healthcare is limited." As such, healthcare resources are limited to the target population without the enhancements that investigators provided to the treatment facilities. Overall, the study's findings still provide important information regarding the recent Clade Ib strain of Mpox that can advance academic knowledge about the virus.Would it benefit from language editing? No The preprint has minimal language errors, but it does not impact the understanding of the paper.Would you recommend this preprint to others? Yes, but it needs to be improved The preprint offers valuable insights into the Clade Ib Mpox outbreak, highlighting key findings like symptom variation across demographics and vertical transmission. Addressing gaps such as clearer definitions (e.g., "skin-to-skin contact") and details on in-hospital mortality and participant loss would enhance its clarity and impact.Is it ready for attention from an editor, publisher or broader audience? Yes, after minor changes The study is well-structured and offers important contributions. Clarifications like genomic evidence for Clade Ib attribution and improved data visualizations would ensure the findings are communicated to a wider audience.Competing interests
The authors declare that they have no competing interests.
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