An observational study in Mpox (Monkeypox), sponsored by Osaka Metropolitan University. Enrolling by invitation at 1 site in Democratic Republic of the Congo. Per ClinicalTrials.gov, last updated 2025-07-09.
Sponsored by Osaka Metropolitan University · Observational
The goal of this observational study is to characterize the clinical features of the 2024 mpox outbreak in Equateur Province of DRC and to identify associated risk factors. The main question it aims to answer is:
Mpox is caused by the monkeypox virus (MPXV), a member of the genus Orthopoxvirus (family Poxviridae). This virus is closely related to the variola virus, which causes smallpox. MPXV was first identified in 1958, and the first human case was reported in the Democratic Republic of the Congo (DRC) in 1970. It was presumed that the smallpox (vaccinia) vaccine would confer cross-protection against mpox. Following the global eradication of smallpox in 1980, mpox remained largely confined to limited regions in Central Africa-where zoonotic spillover from wild animal reservoirs constituted the primary route of transmission. Equateur Province is among the areas in the DRC with a notably high burden of reported mpox cases.
Over the past five decades, routine smallpox vaccination ceased worldwide, resulting in waning herd immunity against orthopoxviruses. During this period, mpox incidence rose markedly, with an estimated tenfold increase in global cases. Two principal genetic clades of MPXV have been identified: clade I (historically referred to as the Congo Basin clade) and clade II (the West African clade). In 2018, Nigeria experienced a resurgence of mpox, highlighting the virus's potential to emerge in previously controlled areas. Starting in 2022, clade II mpox circulated globally, especially among men who have sex with men (MSM), peaking in mid-2022 before declining to persistently lower levels by early 2023. Although clade II mpox typically exhibits a low case-fatality ratio (\<1%), clade I has historically been associated with more severe disease and higher mortality. In 2023, the number of reported mpox cases continued to climb in the DRC, prompting the World Health Organization (WHO) to declare a Public Health Emergency of International Concern (PHEIC) in August 2024.
Recent surveillance indicates that sub-clade Ia MPXV is spreading in western DRC through multiple transmission modes, including contact with infected wild animals, household exposure, or sexual contact. By contrast, sub-clade Ib mpox in the eastern part of the country appears initially to spread via intimate or sexual contact between adults, followed by household transmission. Numerous environmental and social risk factors-including the consumption of rodent species, deforestation, climate change, civil unrest, population displacement, emerging MPXV variants, and weakened immunity-may be driving mpox incidence. Clade Ia mpox is currently affecting western parts of the DRC, yet the epidemiology remains poorly understood due to the limited number of laboratory-confirmed cases.
This study aims to characterize the clinical features of the 2024 mpox outbreak in Equateur Province of DRC and to identify associated risk factors. The findings will advance understanding of mpox transmission dynamics and disease severity, ultimately informing more effective prevention and control strategies in endemic settings.
72 studies on the registry are indexed under Mpox, Monkeypox; 30 are open to participants now.
This study's planned enrollment of 122 is below the median of 224 across 34 observational studies indexed under Mpox, Monkeypox.
Browse Mpox, Monkeypox studies →Osaka Metropolitan University is the lead sponsor of 6 studies on the registry; 5 are open to participants now.
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This study targets patients reported as suspected mpox cases (all ages, both sexes) to the Health District Central Office in the selected sites. For participants aged under 15 years or those with impaired communication abilities (e.g., due to altered consciousness or severe medical conditions), consent must be obtained from a parent, legal guardian, or responsible caregiver. The study population is designed to minimize selection bias related to health-seeking behavior.
All patients suspected of having mpox and who provide proxy-assisted written informed consent to participate in the study are eligible for inclusion due to reduction of the risk of contact transmission with verbal agreement documented and confirmed by a witness. This approach prioritizes participant and staff safety while adhering to ethical standards.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
At least one of the following symptoms:
Fever preceding the eruption. Lymphadenopathy (inguinal, axillary, or cervical). Presence of pustules or crusts on the palms of the hands or soles of the feet. • Laboratory confirmation: At least one molecular-based mpox diagnostic test confirming the diagnosis.
Exclusion Criteria:
Participants will be excluded from the study under the following conditions:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cases are defined as Individuals who reported to local health agents with symptoms consistent with mpox and subsequently tested positive for mpox through a molecular-based diagnostic test.
Controls are defined as Individuals who reported to local health agents with symptoms consistent with mpox but subsequently tested negative for mpox through a molecular-based diagnostic test. Among individuals with a negative molecular diagnostic test for mpox, those who have passed more than 21 days since the onset of mpox-like signs and symptoms or those whom serological testing confirms prior exposure to mpox will be excluded as controls from analysis to avoid confounding results. Rationale: It is not possible to reliably distinguish between uninfected individuals and convalescents. Previous studies suggest a median recovery time of approximately 21 days.
Mpox positivity
Mpox positivity is determined based on one or more molecular-based diagnostic tests. In addition to standard diagnostic methods, the study will assess the performance of novel diagnostic platforms, such as loop-mediated isothermal amplification (LAMP) assays. These platforms will be evaluated for sensitivity, specificity, and overall diagnostic accuracy compared to established molecular-based techniques.
Time frame: Day 1
Virological Course
Genotypes and longitudinal changes in viral load (measured as copies/mL) will be monitored over multiple time points during the study period. Genotypes and quantitative viral load dynamics will reflect disease progression and the timeline of viral clearance, providing insights into the natural course of infection.
Time frame: Day1 and 3-4 weeks after baseline
Disease outcome
Mpox severity will be evaluated based on skin lesion burden, clinical complications, organ dysfunction, and mortality outcomes. Scoring Criteria: Mild: Fewer than 25 lesions. Moderate: 26-99 lesions. Severe: 100 or more lesions or the presence of organ dysfunction, regardless of lesion count. Fatal Outcome: If a patient dies from mpox or its complications during the study, the case will be classified as "fatal outcome." Assessment: The severity score will integrate the number of skin lesions across various anatomical sites and documented signs of complications (e.g., respiratory distress, neurological symptoms, renal impairment).
Time frame: Day1 and 3-4 weeks after baseline
Serological Response
The serological response will be assessed through the detection and quantification of mpox-specific antibodies(Arbitrary Unit) at different time points. Evaluate the kinetics of the humoral immune response during and after infection. Determine correlations between serological responses, disease severity, and virological clearance.
Time frame: Day1 and 3-4 weeks after baseline
Performance of Novel Diagnostic Platforms
To compare the performance of LAMP-based diagnostics and other emerging diagnostic methods with conventional molecular techniques like PCR. Outcome Metrics: Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and turnaround time.
Time frame: Day 1
Clinical Recovery
Defined by the resolution of symptoms and the absence of detectable viral load during follow-up assessments.
Time frame: 3-4 weeks after baseline
Plan to share: Undecided
Started Aug 2024 (actual). Primary completion is estimated for Dec 2025, 16 months after the start.
Of 23 observational studies under Mpox, Monkeypox, half reached primary completion within 18 months of starting (the median), counting those still running; a quarter within 10 and three quarters within 45. This study's planned 16 months is below that.
How these figures are worked out, and which studies are left out of them.
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Osaka Metropolitan University