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Tecovirimat is available for the treatment of mpox (formerly known as monkeypox) in Europe and the United States, on the basis of findings from efficacy studies in animals and safety evaluations in healthy humans. Evidence from randomized, controlled trials of safety and efficacy in patients with mpox is lacking. We conducted a double-blind, randomized, placebo-controlled trial of tecovirimat in patients with mpox in the Democratic Republic of Congo (DRC). Patients with at least one mpox skin lesion and positive polymerase-chain-reaction results for clade I MPXV were assigned in a 1:1 ratio to receive tecovirimat or placebo. All patients received supportive care. The primary end point was resolution of mpox lesions, measured in number of days after randomization. Safety was also assessed. From October 7, 2022, through July 9, 2024, a total of 597 patients underwent randomization - 295 to receive tecovirimat and 302 to receive placebo. The median time from randomization to lesion resolution was 7 days with tecovirimat and 8 days with placebo; the competing-risks hazard ratio for lesion resolution was 1.13 (95% confidence interval [CI], 0.97 to 1.31; P = 0.14). Results were similar whether patients began the trial regimen within 7 days after the reported onset of symptoms (competing-risks hazard ratio, 1.16; 95% CI, 0.98 to 1.37) or more than 7 days after onset (competing-risks hazard ratio, 1.00; 95% CI, 0.71 to 1.40). Overall mortality was 1.7%, which was lower than the case fatality rate of 4.6% reported in the DRC in 2023. At 14 days, the percentages of patients who had blood, lesion, and oropharyngeal samples negative for MPXV by PCR were similar in the two groups. Adverse events occurred in 72.9% of the patients in the tecovirimat group and 70.5% of those in the placebo group, and serious adverse events were reported in 5.1% and 5.0%, respectively. Tecovirimat did not reduce the number of days to lesion resolution in patients with mpox caused by clade I MPXV. No safety concerns were identified. (Funded by the National Institute of Allergy and Infectious Diseases and others; PALM007 ClinicalTrials.gov number, NCT05559099.).

Several concurrent mpox outbreaks are ongoing in the Democratic Republic of the Congo. We report a case of severe clade Ia mpox in an adult woman with indeterminate HIV status who died 16 days after symptom onset. She self-identified as a sex worker and had spent time in the capital city, Kinshasa.

The largest monkeypox virus (MPXV) outbreak described so far in non-endemic countries was identified in May 2022 (refs. 1 – 6 ). In this study, shotgun metagenomics allowed the rapid reconstruction and phylogenomic characterization of the first MPXV outbreak genome sequences, showing that this MPXV belongs to clade 3 and that the outbreak most likely has a single origin. Although 2022 MPXV (lineage B.1) clustered with 2018–2019 cases linked to an endemic country, it segregates in a divergent phylogenetic branch, likely reflecting continuous accelerated evolution. An in-depth mutational analysis suggests the action of host APOBEC3 in viral evolution as well as signs of potential MPXV human adaptation in ongoing microevolution. Our findings also indicate that genome sequencing may provide resolution to track the spread and transmission of this presumably slow-evolving double-stranded DNA virus. Analysis of the first sequences from the 2022 multi-country outbreak of monkeypox virus shows relatedness and substantial divergence from a 2018–2019 outbreak, suggesting rapid virus evolution with possible implications for human-to-human transmission.

Monkeypox, a zoonotic disease caused by an orthopoxvirus, results in a smallpox-like disease in humans. Since monkeypox in humans was initially diagnosed in 1970 in the Democratic Republic of the Congo (DRC), it has spread to other regions of Africa (primarily West and Central), and cases outside Africa have emerged in recent years. We conducted a systematic review of peer-reviewed and grey literature on how monkeypox epidemiology has evolved, with particular emphasis on the number of confirmed, probable, and/or possible cases, age at presentation, mortality, and geographical spread. The review is registered with PROSPERO (CRD42020208269). We identified 48 peer-reviewed articles and 18 grey literature sources for data extraction. The number of human monkeypox cases has been on the rise since the 1970s, with the most dramatic increases occurring in the DRC. The median age at presentation has increased from 4 (1970s) to 21 years (2010–2019). There was an overall case fatality rate of 8.7%, with a significant difference between clades—Central African 10.6% (95% CI: 8.4%– 13.3%) vs. West African 3.6% (95% CI: 1.7%– 6.8%). Since 2003, import- and travel-related spread outside of Africa has occasionally resulted in outbreaks. Interactions/activities with infected animals or individuals are risk behaviors associated with acquiring monkeypox. Our review shows an escalation of monkeypox cases, especially in the highly endemic DRC, a spread to other countries, and a growing median age from young children to young adults. These findings may be related to the cessation of smallpox vaccination, which provided some cross-protection against monkeypox, leading to increased human-to-human transmission. The appearance of outbreaks beyond Africa highlights the global relevance of the disease. Increased surveillance and detection of monkeypox cases are essential tools for understanding the continuously changing epidemiology of this resurging disease.

Monkeypox is a zoonotic disease caused by monkeypox virus (MPXV), which is a member of orthopoxvirus genus. The reemergence of MPXV in 2017 (at Bayelsa state) after 39 years of no reported case in Nigeria, and the export of travelers’ monkeypox (MPX) from Nigeria to other parts of the world, in 2018 and 2019, respectively, have raised concern that MPXV may have emerged to occupy the ecological and immunological niche vacated by smallpox virus. This review X-rays the current state of knowledge pertaining the infection biology, epidemiology, and evolution of MPXV in Nigeria and worldwide, especially with regard to the human, cellular, and viral factors that modulate the virus transmission dynamics, infection, and its maintenance in nature. This paper also elucidates the role of recombination, gene loss and gene gain in MPXV evolution, chronicles the role of signaling in MPXV infection, and reviews the current therapeutic options available for the treatment and prevention of MPX. Additionally, genome-wide phylogenetic analysis was undertaken, and we show that MPXV isolates from recent 2017 outbreak in Nigeria were monophyletic with the isolate exported to Israel from Nigeria but do not share the most recent common ancestor with isolates obtained from earlier outbreaks, in 1971 and 1978, respectively. Finally, the review highlighted gaps in knowledge particularly the non-identification of a definitive reservoir host animal for MPXV and proposed future research endeavors to address the unresolved questions.

We propose a novel, non-discriminatory classification of monkeypox virus diversity. Together with the World Health Organization, we named three clades (I, IIa and IIb) in order of detection. Within IIb, the cause of the current global outbreak, we identified multiple lineages (A.1, A.2, A.1.1 and B.1) to support real-time genomic surveillance.

In September 2018, monkeypox virus was transmitted from a patient to a healthcare worker in the United Kingdom. Transmission was probably through contact with contaminated bedding. Infection control precautions for contacts (vaccination, daily monitoring, staying home from work) were implemented. Of 134 potential contacts, 4 became ill; all patients survived.

Outbreaks of monkeypox (mpox) have historically resulted from zoonotic spillover of clade I monkeypox virus (MPXV) in Central Africa and clade II MPXV in West Africa. In 2022, subclade IIb caused a global epidemic linked to transmission through sexual contact. Here we describe the epidemiological and genomic features of an mpox outbreak in a mining region in eastern Democratic Republic of the Congo, caused by clade I MPXV. Surveillance data collected between September 2023 and January 2024 identified 241 suspected cases. Genomic analysis demonstrates a distinct clade I lineage divergent from previously circulating strains in the Democratic Republic of the Congo. Of the 108 polymerase chain reaction-confirmed mpox cases, the median age of individuals was 22 years, 51.9% were female and 29% were sex workers, suggesting a potential role for sexual transmission. The predominance of APOBEC3-type mutations and the estimated emergence time around mid-September 2023 imply recent sustained human-to-human transmission. Genomic and epidemiologic analyses of monkeypox cases stemming from a recent outbreak in the Democratic Republic of the Congo suggest that a new clade I lineage is circulating and that its spread may be linked to sexual transmission.

In May 2019, we investigated monkeypox in a traveler from Nigeria to Singapore. The public health response included rapid identification of contacts, use of quarantine, and postexposure smallpox vaccination. No secondary cases were identified. Countries should develop surveillance systems to detect emerging infectious diseases globally.

Human mpox (monkeypox), a disease with similarities to smallpox, is endemic in Africa where it has persisted as a zoonosis with limited human-to-human spread. Unexpectedly, the disease expanded globally in 2022 driven by human-to-human transmission outside of Africa. It is not yet known whether the latter is due solely to behavioral and environmental factors or whether the mpox virus is adapting to a new host. Genome sequencing has revealed differences between the current outbreak strains, classified as clade IIb, and the prior clade IIa and clade I viruses, but whether these differences contribute to virulence or transmission has not been determined. We demonstrate that the wild-derived inbred castaneous mouse provides an exceptional animal model for investigating clade differences in mpox virus virulence and show that the order is clade I > clade IIa > clade IIb.1. The greatly reduced replication of the clade IIb.1 major outbreak strain in mice and absence of lethality at 100 times the lethal dose of a closely related clade IIa virus, despite similar multiplication in cell culture, suggest that clade IIb is evolving diminished virulence or adapting to other species.