A-Z Index × Submit A-Z Index × Submit A-Z Index Search Dropdown × Submit Facebook Twitter LinkedIn Syndicate Emerging Infectious Disease journal ISSN: 1080-6059 Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released.
In this meta-analysis, we performed a literature search for articles relating to asymptomatic monkeypox virus (MPXV) detections published worldwide during May 12, 2022–September 13, 2024. The primary outcome was to determine the pooled prevalence of asymptomatic MPXV detections. We conducted a random-effects analysis that yielded a final pooled prevalence of 1.0% (95% prediction interval 0.1%–11.2%). Results did not substantially differ by geographic region or study design. Although those findings are reassuring, we did not evaluate infectivity or transmission potential among asymptomatic persons. MPXV continues to circulate globally; the viral dynamics that enable its persistence remain poorly understood and merit further study.
Clade IIb of human monkeypox virus (MPXV), which causes mpox, an infectious disease in the same family as smallpox, began spreading globally in 2022 and prompted international public health concern ( 1 ). MPXV can be transmitted through close or intimate contact between humans, through infected animals, or through fomites ( 1 ). In the United States, most MPXV infections are spread person-to-person through sexual contact, primarily among gay, bisexual, and other men who have sex with men (GBMSM) ( 1 ). The emergence of the disease in the United States and Europe, where clinical and epidemiologic resources are more abundant than sub-Saharan Africa, has improved our understanding of the clinical manifestations and epidemiologic characteristics of MPXV. It is now understood that MPXV can be transmitted in 1–4 days before a person has onset of symptoms of infection ( 1 ). However, whether persons who remain asymptomatic throughout the course of infection can transmit MPXV to others is much less clear. This uncertainty arises partly because persons need to have lesions to be clinically tested for MPXV in the United States. The prevalence of asymptomatic MPXV infection in the ongoing global outbreak also is unknown and could have important implications for public health efforts.
A previous systematic review and meta-analysis of the prevalence of asymptomatic MPXV detections estimated a pooled prevalence of 10.2% (95% CI 2.5%–17.9%) but only included reports available through September 2022 ( 2 ). Because most studies in that meta-analysis preceded the 2022 global MPXV outbreak and the analysis also included a report from an outbreak that began in a primate sanctuary in Cameroon, the results may not be generalizable to the ongoing outbreak that primarily affects GBMSM ( 2 ).
The absence of asymptomatic MPXV detections in study populations has been noted in numerous reports ( 3 – 8 ). For example, a retrospective study noted that only 0.2% of patients tested through PCR were asymptomatic. However, that study was conducted in the summer and fall of 2022, the peak of the global outbreak, when transmission was more widespread in the GBMSM community ( 9 ). In contrast, 2 studies that assessed the prevalence of asymptomatic MPXV detections among GBMSM in France and Belgium retrospectively screened anorectal, urine, and oropharyngeal samples and found higher prevalences of asymptomatic detect…